A method of casting a 3D printed shell that solidifies layer by layer
By combining DLP printing technology with a directional solidification furnace, the problems of low efficiency and precision in traditional casting mold manufacturing have been solved, enabling efficient and precise casting production with uniform internal structure and high material utilization.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- SHAANXI SIRUI COPPER ALLOY INNOVATION CENT CO LTD
- Filing Date
- 2023-10-27
- Publication Date
- 2026-05-29
Smart Images
Figure CN117463943B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of 3D printing technology, specifically to a casting method for solidifying a 3D printed shell layer by layer. Background Technology
[0002] Traditional sand casting requires the cooperation of mold manufacturers for production, which cannot meet the needs of rapid research and development of new products. In addition, the wall thickness of molds manufactured by traditional processes is usually not less than 35mm, which is not conducive to heat dissipation and venting during the casting process.
[0003] 3D printing technology can utilize three-dimensional models to integrate the four traditional processes of mold making, modeling, core making, and assembly into a single process using 3D printing and intelligent molding. However, 3D printing requires powder as the molding material, and the resulting molds are relatively thick, resulting in low precision and low printing efficiency. Therefore, this paper presents a method for casting parts using a 3D printed shell that solidifies layer by layer. Summary of the Invention
[0004] To address the aforementioned technical problems, this invention provides a casting method for solidifying a 3D printed shell layer by layer.
[0005] The technical solution of this invention is: a casting method for layer-by-layer solidification of a 3D printed shell, comprising the following steps:
[0006] S1, Filling with powder
[0007] Nano-sized alumina powder is loaded into the resin tank of the DLP printing equipment, and a binder is added to the resin tank.
[0008] S2, Printing and shaping
[0009] The resin tank is irradiated at specific points using a DLP printing device, and the shell blank is obtained after the adhesive is cured.
[0010] S3, Degreasing and Preheating
[0011] The casting block and the shell blank are placed into the preheating chamber of the directional solidification furnace, and the casting block is placed on top of the shell blank. Then the preheating chamber is turned on to heat it, so that the temperature inside the preheating chamber reaches 580~620℃ and is held for 100~140 minutes to degrease the shell blank and preheat the casting block at the same time.
[0012] S4, sintering and filling
[0013] The casting block and the shell blank are transferred to the high-temperature chamber of the directional solidification furnace, and the temperature inside the high-temperature chamber is raised to 1400~1600℃ and held for 160~200min. The shell blank is sintered at high temperature, while the casting block melts into molten metal at high temperature and penetrates into the shell blank to obtain the filled shell.
[0014] S5, Layer-by-layer solidification
[0015] The filled mold shell is removed from the high-temperature chamber, and then demolded to obtain the printed mold shell and the casting.
[0016] Explanation: The above method uses DLP technology to print alumina powder into a mold blank, and the casting process can be carried out directly while the mold blank is being sintered, ultimately obtaining both the casting and the mold blank. Since the casting and mold blank sintering processes are carried out simultaneously, production efficiency is improved. Furthermore, the mold blank printing uses DLP technology, which has high printing accuracy and fast printing speed. The mold blank has a relatively thin wall thickness and can be reused multiple times. When the mold blank is removed from the high-temperature chamber, the casting can solidify layer by layer, allowing the molten metal to automatically shrink under the action of gravity, thus avoiding defects such as porosity inside the casting.
[0017] Furthermore, in step S1, the adhesive is a light-curing resin.
[0018] Note: The UV-cured resin has good bonding properties, and the product after high-temperature treatment is non-polluting and safe to use.
[0019] Furthermore, in step S2, the wall thickness of the shell blank is 5-8 mm.
[0020] Note: Controlling the wall thickness of the shell blank ensures that the shell blank has high strength and good heat dissipation performance.
[0021] Furthermore, in step S3, the heating rate of the preheating chamber during the heating process is 0.5℃ / min.
[0022] Note: Controlling the heating rate can prevent the shell from cracking due to excessive heating.
[0023] Furthermore, in step S4, the heating curve of the high-temperature chamber heating process is as follows: the heating rate is 1~3℃ / min within 600~900℃; the heating rate is 0.5~2℃ / min within 900~1200℃, and the temperature is held at 1200℃ for 80~100min; then the temperature inside the high-temperature chamber is raised to 1400~1600℃ at a heating rate of 0.2~1℃ / min.
[0024] Note: The above heating process ensures the growth of alumina ceramic grains, giving the sintered shell good strength and toughness, and allowing the casting block to melt fully and fill the shell better.
[0025] Furthermore, in step S5, the method for removing the filled mold shell from the high-temperature chamber is as follows:
[0026] S5-1: After filling, the mold shell descends by 4~6mm, and after descending, a cooling gas is sprayed once onto the surface of the mold shell outside the high-temperature chamber. The spraying time is 4~6s and the spraying flow rate is 1800mL / s.
[0027] S5-2: Repeat step S5-1 multiple times, and when h1≤1 / 2h, the height of the mold shell after filling is increased by 3~5mm each time compared to the previous time, and the spraying time of the cooling gas is extended by 1~3s each time compared to the previous time;
[0028] When h1 > 1 / 2h, the height of the mold shell after filling decreases by 3-5mm each time compared to the previous time, and the spraying time of the cooling gas remains unchanged each time. Subsequently, for every 10-12mm increase in h1, the spraying time of the cooling gas decreases by 4-6s until the mold shell after filling is completely removed from the high-temperature chamber. Here, h1 is the height of the mold shell outside the high-temperature chamber, and h is the total height of the mold shell.
[0029] Explanation: By gradually lowering the mold shell after filling and spraying cooling gas onto the surface of the mold shell outside the high-temperature chamber, the casting inside the mold shell can be cooled and formed layer by layer. The height of the mold shell after filling decreases at each descent, which also increases the cooling rate of the casting at first and then decreases. This ensures the cooling rate of the casting while allowing the molten metal inside the mold shell to fully feed, improving the material utilization rate of the casting and resulting in a casting with uniform internal structure and fewer defects.
[0030] Furthermore, each time the filled mold shell descends, the temperature inside the high-temperature chamber rises by 5-10°C.
[0031] Note: After each descent of the mold shell after filling, increasing the temperature inside the high-temperature chamber can ensure the fluidity of the molten metal above the mold shell, allowing the molten metal above the mold shell to be fully replenished.
[0032] Furthermore, the cooling gas is nitrogen at 0~20°C.
[0033] Note: The above-mentioned cooling gas has a good cooling effect and can quickly remove the heat emitted from the surface of the mold shell, allowing the casting inside the mold shell to solidify and take shape.
[0034] The beneficial effects of this invention are:
[0035] (1) The present invention uses DLP process to print alumina powder into shell blanks, and the casting process can be carried out directly while the shell blanks are sintered, so that the casting and the shell are obtained at the same time, which improves the production efficiency. The shell has high printing accuracy and fast printing speed, and the shell can be reused multiple times. When the shell is removed from the high temperature chamber, the casting can be solidified layer by layer, so that the molten metal can automatically replenish and avoid defects in the casting.
[0036] (2) The present invention gradually lowers the mold shell after filling and sprays cooling gas onto the surface of the mold shell outside the high temperature chamber, so that the casting inside the mold shell can be cooled and formed layer by layer. The height of the mold shell after filling decreases first and then decreases each time, so that the cooling speed of the casting also increases first and then decreases. While ensuring the cooling speed of the casting, the molten metal inside the mold shell can be fully fed, which improves the material utilization rate of casting and the resulting casting has a uniform internal structure and fewer defects. Attached Figure Description
[0037] Figure 1 This is a flowchart of the method in Embodiment 1 of the present invention;
[0038] Figure 2 This is a schematic diagram of the directional solidification furnace structure in Embodiment 1 of the present invention;
[0039] Among them, 1-preheating chamber, 2-high temperature chamber, 3-cooling chamber, 4-lifting chamber, 5-lifting plate, and 6-horizontal push plate. Detailed Implementation
[0040] The present invention will now be described in more detail with reference to specific embodiments, so as to better demonstrate the advantages of the present invention.
[0041] Example 1
[0042] like Figure 1 As shown, a method for casting a 3D printed shell through layer-by-layer solidification includes the following steps:
[0043] S1, Filling with powder
[0044] Nano-sized alumina powder is loaded into the resin tank of the DLP printing equipment, and a binder is added to the resin tank. The nano-sized alumina powder is spherical powder, and the binder is photocurable resin.
[0045] S2, Printing and shaping
[0046] The resin tank is irradiated at specific points using a DLP printing device. After the adhesive is cured, a shell blank is obtained with a wall thickness of 7mm.
[0047] S3, Degreasing and Preheating
[0048] The casting block and the shell blank are placed into the preheating chamber of the directional solidification furnace, and the casting block is placed on top of the shell blank. Then the preheating chamber is turned on and heated at a rate of 0.5℃ / min to reach a temperature of 600℃ and hold for 120 minutes to degrease the shell blank and preheat the casting block at the same time.
[0049] S4, sintering and filling
[0050] The casting block and the shell blank are transferred to the high-temperature chamber of the directional solidification furnace, and the temperature inside the high-temperature chamber is increased. The heating curve of the high-temperature chamber is as follows: the heating rate is 2℃ / min in the range of 600~900℃; the heating rate is 1℃ / min in the range of 900~1200℃, and the temperature is held at 1200℃ for 90min; then the temperature inside the high-temperature chamber is increased to 1500℃ at a heating rate of 0.5℃ / min and held for 180min, so that the shell blank is sintered at high temperature. At the same time, the casting block melts into molten metal at high temperature and penetrates into the shell blank, thus obtaining the filled shell.
[0051] S5, Layer-by-layer solidification
[0052] The filled mold shell is removed from the high-temperature chamber, and the filled mold shell is demolded to obtain the printed mold shell and the casting. The mold shell is removed from the high-temperature chamber at a constant speed.
[0053] like Figure 2 As shown, a directional solidification furnace in conjunction with the above method is provided, comprising: a preheating chamber 1, a lifting chamber 4, and a cooling chamber 3 arranged sequentially from left to right and connected to each other. A high-temperature chamber 2 connected to the lifting chamber 4 is provided directly above the lifting chamber 4. A lifting plate 5 is vertically slidably connected inside the lifting chamber 4. A hydraulic rod for controlling the lifting of the lifting plate 5 is provided on the bottom surface of the lifting chamber 4. A transverse push plate 6 is horizontally slidably connected inside the preheating chamber 1. A hydraulic rod for controlling the sliding of the transverse push plate 6 is provided on the left side wall of the preheating chamber 1.
[0054] Example 2
[0055] This embodiment is basically the same as Embodiment 1, except that the method for the shell to gradually descend after filling is as follows:
[0056] S5-1: After filling, the mold shell descends by 5mm, and after descending, a cooling gas is sprayed once onto the surface of the mold shell outside the high-temperature chamber. The spraying time is 5s and the spraying flow rate is 1800mL / s.
[0057] S5-2: Repeat step S5-1 multiple times, and when h1≤1 / 2h, the height of the mold shell after filling decreases by 4mm each time compared to the previous time, and the spraying time of the cooling gas is extended by 2s each time compared to the previous time.
[0058] When h1 > 1 / 2h, the height of the mold shell after filling decreases by 4mm each time compared to the previous time, and the spraying time of the cooling gas remains unchanged each time. Then, for every 11mm increase in h1, the spraying time of the cooling gas decreases by 5s until the mold shell after filling is completely removed from the high-temperature chamber. Here, h1 is the height of the mold shell outside the high-temperature chamber, and h is the total height of the mold shell.
[0059] Each time the mold shell descends after filling, the temperature inside the high-temperature chamber rises by 8°C; the cooling gas is nitrogen at 10°C.
[0060] Example 3
[0061] This embodiment is basically the same as Embodiment 1, except that the wall thickness of the shell blank is 5mm.
[0062] Example 4
[0063] This embodiment is basically the same as Embodiment 1, except that the wall thickness of the shell blank is 8mm.
[0064] Example 5
[0065] This embodiment is basically the same as embodiment 1, except that the temperature inside the preheating chamber is made to reach 580°C and kept at that temperature for 100 minutes.
[0066] Example 6
[0067] This embodiment is basically the same as embodiment 1, except that the temperature inside the preheating chamber is raised to 620°C and kept at that temperature for 140 minutes.
[0068] Example 7
[0069] This embodiment is basically the same as Embodiment 1, except that the heating curve of the high-temperature chamber heating process is as follows: the heating rate is 1℃ / min in the range of 600~900℃; the heating rate is 0.5℃ / min in the range of 900~1200℃, and the temperature is held at 1200℃ for 80min; then the temperature inside the high-temperature chamber is raised to 1400℃ at a heating rate of 0.2℃ / min, and held for 160min.
[0070] Example 8
[0071] This embodiment is basically the same as Embodiment 1, except that the heating curve of the high-temperature chamber heating process is as follows: the heating rate is 3℃ / min in the range of 600~900℃; the heating rate is 2℃ / min in the range of 900~1200℃, and the temperature is held at 1200℃ for 100min; then the temperature inside the high-temperature chamber is raised to 1600℃ at a heating rate of 1℃ / min, and held for 200min.
[0072] Example 9
[0073] This embodiment is basically the same as embodiment 2, except that in step S5-1, the mold shell is lowered by 4mm after filling, and after lowering, cooling gas is sprayed onto the surface of the mold shell outside the high temperature chamber once, with a spraying time of 4s.
[0074] Example 10
[0075] This embodiment is basically the same as embodiment 2, except that in step S5-1, the mold shell is lowered by 6mm after filling, and after lowering, cooling gas is sprayed onto the surface of the mold shell outside the high temperature chamber once, with a spraying time of 6s.
[0076] Example 11
[0077] This embodiment is basically the same as embodiment 2, except that in step S5-2, when h1≤1 / 2h, the height of the mold shell after filling decreases by 3mm each time compared to the previous time, and the spraying time of the cooling gas is extended by 1s each time compared to the previous time.
[0078] When h1 > 1 / 2h, the height of the mold shell after filling decreases by 3mm each time compared to the previous time, and the spraying time of the cooling gas remains unchanged each time. Then, for every 10mm increase in h1, the spraying time of the cooling gas decreases by 4s until the mold shell after filling is completely removed from the high-temperature chamber.
[0079] Example 12
[0080] This embodiment is basically the same as embodiment 2, except that in step S5-2, when h1≤1 / 2h, the height of the mold shell after filling decreases by 5mm each time compared to the previous time, and the spraying time of the cooling gas is extended by 3s each time compared to the previous time.
[0081] When h1 > 1 / 2h, the height of the mold shell after filling decreases by 5mm each time compared to the previous time, and the spraying time of the cooling gas remains unchanged each time. Then, for every 12mm increase in h1, the spraying time of the cooling gas decreases by 6s until the mold shell after filling is completely removed from the high-temperature chamber.
[0082] Example 13
[0083] This embodiment is basically the same as embodiment 2, except that the temperature inside the high-temperature chamber increases by 5°C each time the mold shell descends after filling.
[0084] Example 14
[0085] This embodiment is basically the same as embodiment 2, except that the temperature inside the high-temperature chamber increases by 10°C each time the mold shell descends after filling.
[0086] Example 15
[0087] This embodiment is basically the same as Embodiment 2, except that the cooling gas is nitrogen at 0°C.
[0088] Example 16
[0089] This embodiment is basically the same as Embodiment 2, except that the cooling gas is nitrogen at 20°C.
[0090] Experimental Example
[0091] The casting materials used in all the above embodiments are copper-chromium-zirconium alloys, with a Cr content of 0.8%, a Zr content of 0.07%, and the remainder being Cu. The castings prepared in each embodiment are of the same size and shape. Performance tests were conducted on the castings prepared in each embodiment to investigate the influence of the parameters of each embodiment on the casting performance. The specific investigation is as follows:
[0092] 1. Investigate the effect of shell blank wall thickness on casting properties.
[0093] Using Examples 1, 3, and 4 as experimental comparisons, the casting properties of the shell blanks with different wall thicknesses are shown in Table 1 below:
[0094] Table 1. Casting properties of shell blanks with different wall thicknesses
[0095]
[0096] As shown in Table 1, the castings of Example 1 have the highest hardness and electrical conductivity, indicating that the wall thickness of the shell blank selected in Example 1 is optimal.
[0097] 2. Investigate the influence of preheating parameters on casting properties.
[0098] Using Examples 1, 5, and 6 as experimental comparisons, the casting properties under different preheating parameters are shown in Table 2 below:
[0099] Table 2 Casting properties under different preheating parameters
[0100]
[0101] As shown in Table 2, the castings of Example 1 have the highest hardness and electrical conductivity, indicating that the preheating parameters selected in Example 1 are optimal.
[0102] 3. The Influence of High-Temperature Chamber Heating Curve on Casting Properties
[0103] Using Examples 1, 7, and 8 as comparative experiments, and with Example 1 as a reference, the high-temperature chamber was heated at a rate of 2℃ / min throughout the entire process as Comparative Example 1. The casting properties under different heating curves in the high-temperature chamber are shown in Table 3 below:
[0104] Table 3. Casting properties under different heating curves in the high-temperature chamber
[0105]
[0106] As shown in Table 3, compared with Examples 1, 7, and 8, the casting hardness and electrical conductivity of Example 1 are the highest, indicating that the high-temperature chamber heating curve selected in Example 1 is the best. Compared with Comparative Example 1, the casting hardness and electrical conductivity of Example 1 are both higher, indicating that the high-temperature chamber heating method selected in Example 1 is better.
[0107] 4. Investigate the influence of shell cooling methods on casting properties.
[0108] Using Examples 1 and 2 as experimental comparisons, and with Example 1 as a reference, Comparative Example 2 involved directly removing the filled mold shell for overall cooling. The casting properties under different cooling methods are shown in Table 4 below:
[0109] Table 4. Casting properties under different cooling methods
[0110]
[0111] As shown in Table 4, compared with Example 1, the casting hardness and electrical conductivity of Example 2 are both higher, indicating that the shell cooling method selected in Example 2 is better; compared with Comparative Example 2, the casting hardness and electrical conductivity of Example 2 are both higher, indicating that the shell removal method selected in Example 2 is better.
[0112] 5. Investigating the effect of the initial descent height of the mold shell on the performance of the casting.
[0113] Using Examples 2, 9, and 10 as experimental comparisons, the casting properties at different initial descent heights of the shell are shown in Table 5 below:
[0114] Table 5. Casting properties at different initial descent heights of the shell.
[0115]
[0116] As shown in Table 5, the castings of Example 2 have the highest hardness and electrical conductivity, indicating that the initial descent height of the shell selected in Example 2 is optimal.
[0117] 6. Investigate the influence of shell descent parameters on casting properties.
[0118] Using Examples 2, 11, and 12 as comparative experiments, and with Example 2 as a reference, the mold shell descent height was fixed at 5 mm each time after filling, serving as Comparative Example 3. The casting performance under different mold shell descent parameters is shown in Table 6 below:
[0119] Table 6. Casting properties under different descent parameters of the shell.
[0120]
[0121] As shown in Table 6, compared with Real-Time Examples 2, 11, and 12, the casting hardness and electrical conductivity of Example 2 are the highest, indicating that the shell descent parameters selected in Example 2 are optimal. Compared with Comparative Example 3, the casting hardness and electrical conductivity of Example 2 are higher, indicating that the shell descent parameters selected in Example 2 are even better.
[0122] 7. Investigate the effect of temperature change in the high-temperature chamber after the mold shell descends on the properties of the casting.
[0123] Using Examples 2, 13, and 14 as comparative experiments, the casting properties under different temperature changes in the high-temperature chamber after the shell was lowered are shown in Table 7 below:
[0124] Table 7. Casting properties under different temperature variations in the high-temperature chamber
[0125]
[0126] As shown in Table 7, the castings from Example 2 have the highest hardness and electrical conductivity, indicating that the temperature change in the high-temperature chamber selected in Example 2 is optimal.
[0127] 8. Investigate the effect of cooling gas temperature on casting properties.
[0128] Using Examples 2, 15, and 16 as comparative experiments, the casting properties under different cooling gas temperatures are shown in Table 8 below:
[0129] Table 8. Casting properties at different cooling gas temperatures
[0130]
[0131] As shown in Table 8, the castings of Example 2 have the highest hardness and electrical conductivity, indicating that the cooling gas temperature selected in Example 2 is optimal.
Claims
1. A method for casting a 3D-printed shell through layer-by-layer solidification, characterized in that, Includes the following steps: S1, Filling with powder Nano-sized alumina powder is loaded into the resin tank of the DLP printing equipment, and a binder is added to the resin tank. S2, Printing and shaping The resin tank is irradiated at specific points using a DLP printing device, and the shell blank is obtained after the adhesive is cured. S3, Degreasing and Preheating The casting block and the shell blank are placed into the preheating chamber of the directional solidification furnace, and the casting block is placed on top of the shell blank. Then the preheating chamber is turned on to heat it, so that the temperature inside the preheating chamber reaches 580~620℃ and is held for 100~140 minutes to degrease the shell blank and preheat the casting block at the same time. S4, sintering and filling The casting block and the shell blank are transferred to the high-temperature chamber of the directional solidification furnace, and the temperature inside the high-temperature chamber is raised to 1400~1600℃ and held for 160~200min. The shell blank is sintered at high temperature, while the casting block melts into molten metal at high temperature and penetrates into the shell blank to obtain the filled shell. S5, Layer-by-layer solidification The filled mold shell is removed from the high-temperature chamber, and the filled mold shell is demolded to obtain the printed mold shell and the casting; The method for removing the mold shell from the high-temperature chamber after filling is as follows: S5-1: After filling, the mold shell descends by 4~6mm, and after descending, a cooling gas is sprayed once onto the surface of the mold shell outside the high-temperature chamber. The spraying time is 4~6s and the spraying flow rate is 1800mL / s. S5-2: Repeat step S5-1 multiple times, and when h1≤1 / 2h, the height of the mold shell after filling is increased by 3~5mm each time compared to the previous time, and the spraying time of the cooling gas is extended by 1~3s each time compared to the previous time; When h1 > 1 / 2h, the height of the mold shell after filling decreases by 3-5mm each time compared to the previous time, and the spraying time of the cooling gas remains unchanged each time. Subsequently, for every 10-12mm increase in h1, the spraying time of the cooling gas decreases by 4-6s until the mold shell after filling is completely removed from the high-temperature chamber. Here, h1 is the height of the mold shell outside the high-temperature chamber, and h is the total height of the mold shell.
2. The casting method for layer-by-layer solidification of a 3D printed shell according to claim 1, characterized in that, In step S1, the adhesive is a light-curing resin.
3. The casting method for layer-by-layer solidification of a 3D printed shell according to claim 1, characterized in that, In step S2, the wall thickness of the shell blank is 5-8mm.
4. The casting method for layer-by-layer solidification of a 3D printed shell according to claim 1, characterized in that, In step S3, the heating rate of the preheating chamber is 0.5℃ / min.
5. The casting method for layer-by-layer solidification of a 3D printed shell according to claim 1, characterized in that, In step S4, the heating curve of the high-temperature chamber is as follows: the heating rate is 1~3℃ / min within 600~900℃; the heating rate is 0.5~2℃ / min within 900~1200℃, and the temperature is held at 1200℃ for 80~100min; then the temperature inside the high-temperature chamber is raised to 1400~1600℃ at a heating rate of 0.2~1℃ / min.
6. The casting method for layer-by-layer solidification of a 3D printed shell according to claim 1, characterized in that, Each time the mold shell descends after filling, the temperature inside the high-temperature chamber rises by 5-10°C.
7. The casting method for layer-by-layer solidification of a 3D printed shell according to claim 1, characterized in that, The cooling gas is nitrogen at 0~20℃.