Anti-deformation aerospace connecting base casting mold and casting method

Abstract

This invention discloses a deformation-resistant aerospace connecting base casting mold and casting method. The mold consists of an upper mold and a lower mold. The lower mold has a cavity, and the upper mold has a core and a gate. The lower mold has a striking mechanism and a rotating ring with wave crests and troughs. A driving mechanism is also provided on the lower mold. The rotating ring has a pressure post and a vertical countersunk hole, connected by a spring. A second striking rod is also provided on the rotating ring, and a transverse countersunk hole is located on the inner wall of the rotating ring, communicating with the vertical countersunk hole. The driving mechanism of this invention drives the rotating ring to rotate, enabling the striking mechanism to move up and down. Simultaneously, the striking mechanism compresses the pressure post, causing the second striking rod to extend and strike the lower mold, allowing the molten metal to fill the gaps in the cavity under vibration.

Description

Technical Field

[0001] This invention relates to the field of metal casting technology, specifically to a deformation-resistant aerospace connecting base casting mold and casting method. Background Technology

[0002] Casting is a process in which metal is melted into a liquid that meets certain requirements and poured into a mold. After cooling and solidification, and cleaning, a casting with a predetermined shape, size, and properties is obtained. Because the cast blank is nearly formed, it achieves the purpose of eliminating or minimizing machining, reducing costs and, to some extent, shortening production time.

[0003] Currently, commonly used casting molds include sand molds, metal molds, and ceramic molds. Sand molds are inexpensive but cannot be reused multiple times and have a short service life. Metal molds offer dimensional stability, high precision, and can be reused multiple times, thus gaining widespread application. However, when casting metals with poor fluidity, the molten metal cannot fully fill the gaps at the edges of the mold cavity, and the molten metal on the casting cannot effectively compensate for shrinkage, leading to defects on the surface or inside of the metal casting. Therefore, this paper proposes a deformation-resistant casting mold and casting method for aerospace connecting bases. Summary of the Invention

[0004] To solve the above-mentioned technical problems, the present invention provides a deformation-resistant aerospace connecting base casting mold and casting method.

[0005] The technical solution of the present invention is: a deformation-resistant aerospace connecting base casting mold, the mold being composed of an upper mold and a lower mold, the lower mold being provided with a cavity for filling molten metal, the upper mold being provided with a core for engaging with the cavity, and the upper mold being provided with a gate for pouring molten metal into the cavity;

[0006] The lower mold sidewall is provided with multiple striking mechanisms in the circumferential direction, and the striking mechanisms are slidably connected to the vertical sliding grooves provided on the lower mold.

[0007] A rotating ring is rotatably connected to the lower mold. The rotating ring has staggered peaks and troughs. The peaks contact the striking mechanism and are used to push the striking mechanism to move upward to the top of the vertical groove. The troughs are separated from the striking mechanism located at the bottom of the vertical groove. A driving mechanism for driving the rotating ring to rotate is provided on the side wall of the lower mold.

[0008] Each of the wave crests and the rotating rings on both sides of the wave crests are provided with multiple pressure columns for contacting the striking mechanism to perform compression. The rotating rings are provided with vertical countersunk holes that are slidably sealed to each of the pressure columns, and the pressure columns and the vertical countersunk holes are connected by springs.

[0009] The inner wall of the rotating ring is provided with multiple second striking rods corresponding to multiple pressure columns. The inner wall of the rotating ring is provided with transverse countersunk holes that are slidably sealed to the second striking rods. The multiple transverse countersunk holes are all connected to the corresponding vertical countersunk holes, and both the transverse countersunk holes and the vertical countersunk holes are filled with hydraulic oil.

[0010] Explanation: The above mold can drive the rotating ring to rotate, causing the rotating disk to push the striking mechanism to move up and down, so that the striking mechanism can strike the lower mold. When the striking mechanism comes into contact with the rotating disk, it will squeeze the pressure column, causing the second striking rod to extend under pressure and strike the lower mold. This allows the molten metal to fill the gaps in the cavity under the vibration generated by the striking, thereby reducing casting defects.

[0011] Furthermore, a connecting plate is provided on the side wall of the lower mold, and the driving mechanism includes a motor fixedly mounted on the connecting plate, a first gear fixedly sleeved on the output shaft of the motor, and a gear ring sleeved on the rotating ring for meshing with the first gear.

[0012] Explanation: The above-mentioned drive mechanism drives the first gear to rotate via a motor, which in turn drives the rotating ring to rotate via the gear ring.

[0013] Furthermore, the striking mechanism includes a slider slidably connected to a vertical groove, a rotating disk rotatably mounted on the slider and used to contact and cooperate with a rotating ring to move upward, a fixed rod fixedly mounted on the rotating disk, and a first striking rod slidably mounted laterally on the fixed rod.

[0014] The rotating disk is rotatably connected to the slider via a rotating shaft fitted with a torsion spring; one end of the first striking rod contacts the side wall of the lower mold, and the other end of the first striking rod passes through the fixed rod. A first limiting ring is fixedly fitted on the first striking rod on one side of the fixed rod, and the first limiting ring is connected to the fixed rod via a liquid bladder. A second limiting ring is fixedly fitted on the first striking rod on the other side of the fixed rod, and the second limiting ring is connected to the fixed rod via a spring.

[0015] The lower mold sidewall is provided with a plurality of protrusions for swinging and engaging with the first striking rod to strike. The first striking rod is provided with a liquid channel for applying lubricating oil to the protrusions, and the liquid channel is connected to the liquid bladder.

[0016] Explanation: When the rotating disk contacts the rotating ring, the striking mechanism will move upward. At the same time, due to the friction, the rotating disk will oscillate intermittently. When the rotating disk oscillates back and forth, it will drive the first striking rod to continuously contact the protrusion, causing the protrusion to intermittently push the first striking rod to reciprocate and strike the lower mold. When the first striking rod strikes, it will intermittently squeeze the liquid bladder, causing the liquid bladder to release lubricating oil onto the protrusion, making the oscillation of the first striking rod smoother.

[0017] Furthermore, the lower mold is provided with a positioning hole, and the upper mold is provided with a positioning pin for engaging with the positioning hole.

[0018] Note: Positioning holes can assist in the positioning of the upper mold, making the position of the upper mold more accurate when the mold is closed. In addition, the manufacturing cost of positioning holes and positioning pins is low and they are practical.

[0019] Furthermore, the top of the vertical groove is connected to the striking mechanism via a spring, and the striking mechanism is equipped with a counterweight.

[0020] Note: A spring is installed at the top of the vertical slide, and a counterweight is installed on the striking mechanism to ensure that the striking mechanism can provide sufficient pressure to squeeze the pressure column.

[0021] Furthermore, the distance between any two adjacent pressure columns on the rotating ring is less than 1 / 2 of the arc length of a single swing of the rotating disk.

[0022] Note: Limiting the distance between the pressure pillars and ensuring the contact frequency between the rotating disc and the pressure pillars are crucial for achieving the desired striking effect.

[0023] Furthermore, the method for preparing the lower mold includes the following steps:

[0024] S1, Take powder

[0025] Take n grades of silicon carbide powder and n grades of alumina powder, where n is a natural number of 4≤n≤6. The particle size of silicon carbide powder gradually decreases as the grade increases, while the particle size of alumina powder gradually increases as the grade increases. The particle size of the n grades of silicon carbide powder is between 5μm and 400μm, and the particle size of the n grades of alumina powder is between 5μm and 300μm.

[0026] S2, Mixed Powder

[0027] Silicon carbide powder of different grades is mixed with alumina powder of corresponding grades to obtain mixed powder of different grades; wherein, the proportion of alumina powder in the first grade mixed powder is 50-60%, and the proportion of alumina powder in each subsequent grade mixed powder is reduced by 2-4% compared with the previous grade.

[0028] S3, 3D printing

[0029] The first-stage mixed powder is loaded into a 3DP printer for layer-by-layer printing, where each layer is t thick. After every x layers are printed, the next stage of mixed powder is used for printing, until the blank of the lower mold is printed. The value of x conforms to the following formula:

[0030]

[0031] Where h is the height of the lower mold, in mm; n is the grade and quantity of silicon carbide powder and alumina powder; 0.6≤t≤0.1, in mm;

[0032] S4, sintering

[0033] The blank is placed in a sintering furnace, and the furnace is gradually heated to 2000-2200°C. After holding at this temperature for 6-8 hours, the blank is removed from the furnace and cooled to obtain the lower mold.

[0034] Note: The above mold is made of alumina powder and silicon carbide powder. The mold has high overall strength, excellent heat dissipation performance, can be reused multiple times, and has a smooth surface for easy demolding. At the same time, alumina powder and silicon carbide powder of different particle sizes are mixed into various levels of powder, which makes the internal structure of the mold dense. The content of alumina powder gradually changes from top to bottom of the mold, so the thermal conductivity of the mold gradually increases from top to bottom. The molten metal can solidify layer by layer in the mold. After the molten metal at the bottom solidifies, the molten metal at the top can automatically replenish the solidification, reducing defects inside the connecting base.

[0035] Furthermore, in step S2, the powder mixing is carried out using a ball mill with a ball-to-material ratio of 1:3 and a mixing time of 30-50 minutes.

[0036] Note: Ball mills have a better powder mixing effect, which can ensure that alumina powder and silicon carbide powder are mixed evenly.

[0037] Further, in step S4, the heating curve of the sintering furnace heating process is as follows: heating to 800-900℃ at a rate of 10-15℃ / min, then heating to 1400-1500℃ at a rate of 6-8℃ / min, then heating to 1800-1900℃ at a rate of 3-5℃ / min and holding for 1-2 hours, and then heating to 2000-2200℃ at a rate of 0.5-2℃ / min.

[0038] Note: The above heating curve can ensure the sintering rate, while avoiding defects such as cracking inside the mold and improving the dimensional stability of the mold.

[0039] On the other hand, the present invention provides a method for casting a connecting base using the above-mentioned mold, comprising the following steps:

[0040] S4-1. Place the metal raw material into the melting furnace for melting. After the metal raw material is melted into molten metal, let it stand for 2 to 5 minutes. Then close the upper mold and the lower mold. Then start the drive mechanism to make the drive mechanism drive the rotating ring to rotate and pour the molten metal into the cavity through the gate for casting, so that the cavity is filled with molten metal.

[0041] S4-2. When the rotating ring rotates, it will intermittently contact the striking mechanism, allowing the striking mechanism to slide up and down to guide and strike the upper side wall of the lower mold in an up-and-down reciprocating manner. At the same time, the striking mechanism will intermittently squeeze the pressure column.

[0042] S4-3. After being pressed, the pressure column will descend and squeeze the hydraulic oil. The second striking rod will extend under the pressure of the hydraulic oil and rotate through the rotating ring to perform a uniform circumferential striking on the lower side wall of the mold, so that the molten metal can fill the gap in the cavity under the vibration generated by the striking.

[0043] S4-4. Wait for the molten metal to solidify and take out the upper mold to obtain the connecting base.

[0044] Explanation: The above casting method can ensure that the molten metal solidifies layer by layer from bottom to top. The hammering mechanism can guide the upper side wall of the lower mold to hammer back and forth, while the second hammering rod can hammer the lower side wall of the lower mold in a circular motion. By combining the two hammering methods, the molten metal in the upper part of the mold can flow downward under the vibration and automatically shrink, thereby reducing internal defects of the connecting base and improving the performance of the connecting base.

[0045] The beneficial effects of this invention are:

[0046] (1) The mold of the present invention can drive the rotating ring to rotate through the driving mechanism, so that the rotating disk pushes the striking mechanism to move up and down, so that the striking mechanism can strike the lower mold. When the striking mechanism comes into contact with the rotating disk, it will squeeze the pressure column, so that the second striking rod extends under pressure to strike the lower mold, so that the molten metal can fill the gap in the cavity under the vibration generated by the striking, thereby reducing casting defects.

[0047] (2) The mold of the present invention is made of alumina powder and silicon carbide powder. The mold has high overall strength, excellent heat dissipation performance, can be reused multiple times, and has a smooth surface, making it easy to demold. At the same time, the content of alumina powder in the mold gradually changes from top to bottom, so that the thermal conductivity of the mold gradually increases from top to bottom, allowing the molten metal to solidify layer by layer in the mold and reducing defects inside the connecting base.

[0048] (3) The casting method of the present invention can ensure that the molten metal solidifies layer by layer from bottom to top. The striking mechanism can guide the upper side wall of the lower mold to strike back and forth. At the same time, the second striking rod can strike the lower side wall of the lower mold in a circular manner. By combining the two striking methods, the molten metal in the upper part of the mold can flow downward under the action of vibration and automatically shrink, so as to reduce the internal defects of the connecting base and improve the performance of the connecting base. Attached Figure Description

[0049] Figure 1 This is a schematic diagram of the mold structure in Embodiment 1 of the present invention;

[0050] Figure 2 This is a schematic diagram of the rotating ring structure in Embodiment 1 of the present invention;

[0051] Figure 3 for Figure 2 Enlarged view of point A

[0052] Figure 4 Schematic diagram of the second striking rod structure in Embodiment 1 of the present invention;

[0053] Figure 5 This is a schematic diagram of the striking mechanism structure in Embodiment 1 of the present invention;

[0054] Figure 6 This is a schematic diagram of the first striking rod structure in Embodiment 1 of the present invention;

[0055] Among them, 1-upper mold, 11-core, 12-gate, 2-lower mold, 21-connecting plate, 22-cavity, 3-rotating ring, 31-wave crest, 32-first gear, 33-gear ring, 34-pressure column, 35-second striking rod, 36-motor, 37-wave trough, 4-striking mechanism, 41-slider, 42-rotating disk, 43-fixed rod, 44-first striking rod, 45-protrusion, 46-first limiting ring, 47-liquid bladder, 48-second limiting ring. Detailed Implementation

[0056] 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.

[0057] Example 1

[0058] like Figure 1 As shown, a deformation-resistant aerospace connecting base casting mold is provided. The mold consists of an upper mold 1 and a lower mold 2. The lower mold 2 is provided with a cavity 22 for filling molten metal. The upper mold 1 is provided with a core 11 for cooperating with the cavity 22. The upper mold 1 is provided with a gate 12 for pouring molten metal into the cavity 22.

[0059] The lower mold 2 has multiple striking mechanisms 4 circumferentially arranged on its side wall, and the striking mechanisms 4 are slidably connected to the vertical sliding grooves provided on the lower mold 2.

[0060] like Figure 2 As shown, a rotating ring 3 is rotatably connected to the lower mold 2. The lower mold 2 is rotatably connected to the rotating ring 3 through an annular groove provided on the side wall. The rotating ring 3 has six staggered peaks 31 and valleys 37. The peaks 31 contact the striking mechanism and are used to push the striking mechanism 4 to move upward to the top of the vertical slide groove. The valleys 37 are separated from the striking mechanism 4 located at the bottom of the vertical slide groove. The side wall of the lower mold 2 is provided with a driving mechanism for driving the rotating ring 3 to rotate.

[0061] The lower mold 2 has a connecting plate 21 on its side wall. The driving mechanism includes a motor 36 fixedly mounted on the connecting plate 21. The motor 36 adopts existing technology products, a first gear 32 fixedly mounted on the output shaft of the motor 36, and a gear ring 33 mounted on the rotating ring 3 and used to mesh with the first gear 32.

[0062] like Figure 3 As shown, each of the wave crests 31 and the rotating rings 3 on both sides of the wave crest 31 are provided with three pressure columns 34 for contacting the striking mechanism 4 to perform compression. The rotating ring 3 is provided with vertical countersunk holes that are slidably sealed to the pressure columns 34 one by one, and the pressure columns 34 and the vertical countersunk holes are connected by springs.

[0063] The inner wall of the rotating ring 3 is provided with eighteen second striking rods 35 corresponding to eighteen pressure columns 34. The inner wall of the rotating ring 3 is provided with transverse countersunk holes that are slidably sealed and connected to the second striking rods 35. All eighteen transverse countersunk holes are connected to the corresponding vertical countersunk holes, and both the transverse countersunk holes and the vertical countersunk holes are filled with hydraulic oil.

[0064] like Figure 5 As shown, the striking mechanism includes a slider 41 slidably connected to a vertical slide groove, a rotating disk 42 rotatably disposed on the slider 41 and used to contact and cooperate with the rotating ring 3 to move upward, a fixed rod 43 fixedly disposed on the rotating disk 42, and a first striking rod 44 slidably disposed laterally on the fixed rod 43.

[0065] like Figure 6 As shown, the rotating disk 42 is rotatably connected to the slider 41 via a rotating shaft fitted with a torsion spring. The left end of the first striking rod 44 contacts the side wall of the lower mold 2, and the right end of the first striking rod 44 passes through the fixed rod 43. A first limiting ring 46 is fixedly fitted on the first striking rod 44 on the left side of the fixed rod 43, and the first limiting ring 46 is connected to the fixed rod 43 via a liquid bladder 47. A second limiting ring 48 is fixedly fitted on the first striking rod 44 on the right side of the fixed rod 43, and the second limiting ring 48 is connected to the fixed rod 43 via a spring.

[0066] The lower mold 2 has thirty-six protrusions 45 on its side wall for swinging and engaging with the first striking rod 44 to strike. The outer side wall of the protrusions 45 is chamfered. The first striking rod 44 has a liquid channel for applying lubricating oil to the protrusions 45. The liquid channel is connected to the liquid bladder 47.

[0067] The lower mold 2 is provided with a positioning hole, and the upper mold 1 is provided with a positioning pin for cooperating with the positioning hole; the top of the vertical slide groove is connected to the striking mechanism by a spring, and the striking mechanism is provided with a counterweight; the distance between every two adjacent pressure columns 34 on the rotating ring 3 is 1 / 4 of the arc length of a single swing of the rotating disk 42;

[0068] The method for casting the connecting base using the above-mentioned casting mold includes the following steps:

[0069] S4-1. Place the metal raw material into the melting furnace for melting. After the metal raw material is melted into molten metal, let it stand for 2-5 minutes. Then, close the upper mold 1 and the lower mold 2. Then, start the drive mechanism to make the drive mechanism drive the rotating ring 3 to rotate. Pour the molten metal into the cavity 22 through the gate 12 for casting, so that the cavity 22 is filled with molten metal. The metal raw material is aluminum alloy.

[0070] S4-2. During the rotation of the rotating ring 3, it will intermittently contact the rotating disk 42 and push the rotating disk 42 to slide up and down. At the same time, due to the friction, the rotating disk 42 will rotate. When the rotating ring 3 continues to rotate to the trough 37 position, the rotating disk 42 separates from the rotating ring 3. Then the rotating disk 42 returns to its original position under the action of the torsion spring, so that the rotating disk 42 can swing intermittently. When the rotating disk 42 swings intermittently, it will drive the first striking rod 44, so that the first striking rod 44 will continuously contact the protrusion 45, so that the first striking rod 44 can be lifted up and down to guide the upper side wall of the lower mold 2 to strike it in an up and down manner. When the first striking rod 44 is lifted, it will squeeze the liquid bladder 47, so that the lubricating oil in the liquid bladder 47 will be released onto the protrusion 45. At the same time, when the pressure column 34 contacts the rotating disk 42, the rotating disk 42 will intermittently squeeze the pressure column 34.

[0071] S4-3, the pressure column 34 will descend and squeeze the hydraulic oil after being pressed. The second striking rod 35 will extend under the pressure of the hydraulic oil and rotate through the rotating ring 3 to perform a uniform circumferential striking on the lower side wall of the lower mold 2, so that the molten metal can fill the gap in the cavity 22 under the vibration generated by the striking.

[0072] S4-4. Wait for the molten metal to solidify and take out the upper mold 1 to obtain the connecting base.

[0073] Example 2

[0074] This embodiment is basically the same as Embodiment 1, except that the preparation method of the lower mold 2 includes the following steps:

[0075] S1, Take powder

[0076] Five grades of silicon carbide powder and five grades of alumina powder were taken. The particle sizes of the silicon carbide powder from grades 1 to 5 were 320–400 μm, 240–320 μm, 160–240 μm, 80–160 μm, and 5–80 μm, respectively; the particle sizes of the alumina powder from grades 1 to 5 were 5–60 μm, 60–120 μm, 120–180 μm, 180–240 μm, and 240–300 μm, respectively.

[0077] S2, Mixed Powder

[0078] Silicon carbide powder of different grades was mixed with alumina powder of corresponding grades to obtain mixed powder of different grades. The mixing was carried out by ball mill with a ball-to-powder ratio of 1:3 and a mixing time of 40 minutes. The alumina powder accounted for 55% of the first-stage mixed powder, and the alumina powder accounted for 3% of each subsequent stage of mixed powder.

[0079] S3, 3D printing

[0080] The first-level mixed powder is loaded into the 3DP printer for layer-by-layer printing, where each layer is t thick. After every x layers are printed, the next level of mixed powder is used for printing, until the blank of the lower mold 2 is printed. The value of x conforms to the following formula:

[0081]

[0082] Where h is 260 mm; n = 5; t = 0.8 mm; and x is calculated to be 65.

[0083] S4, sintering

[0084] The blank is placed in a sintering furnace, and the furnace is gradually heated to 2100°C. After holding at this temperature for 7 hours, the blank is removed from the furnace and cooled to obtain the lower mold 2. The heating curve of the sintering furnace is as follows: the temperature is increased to 850°C at a rate of 12°C / min, then increased to 1450°C at a rate of 7°C / min, then increased to 1850°C at a rate of 4°C / min and held for 1.5 hours, and then increased to 2100°C at a rate of 1°C / min.

[0085] Example 3

[0086] This embodiment is basically the same as Embodiment 1, except that four grades of silicon carbide powder and four grades of alumina powder are used. The particle sizes of the silicon carbide powder of grades 1 to 4 are 300–400 μm, 200–300 μm, 100–200 μm, and 5–100 μm, respectively; the particle sizes of the alumina powder of grades 1 to 4 are 5–80 μm, 80–150 μm, 150–220 μm, and 220–300 μm, respectively.

[0087] Example 4

[0088] This embodiment is basically the same as Embodiment 1, except that six grades of silicon carbide powder and six grades of alumina powder are used; the particle sizes of the silicon carbide powder of grades 1 to 6 are 340–400 μm, 280–340 μm, 220–280 μm, 150–220 μm, 80–150 μm, and 5–80 μm, respectively; the particle sizes of the alumina powder of grades 1 to 6 are 5–50 μm, 50–100 μm, 100–150 μm, 150–200 μm, 200–250 μm, and 250–300 μm, respectively.

[0089] Example 5

[0090] This embodiment is basically the same as embodiment 2, except that the mixing time is 30 minutes.

[0091] Example 6

[0092] This embodiment is basically the same as Embodiment 2, except that the mixing time is 50 minutes.

[0093] Example 7

[0094] This embodiment is basically the same as embodiment 2, except that the proportion of alumina powder in the first-stage mixed powder is 50%.

[0095] Example 8

[0096] This embodiment is basically the same as Embodiment 2, except that the proportion of alumina powder in the first-stage mixed powder is 60%.

[0097] Example 9

[0098] This embodiment is basically the same as Embodiment 2, except that the proportion of alumina powder in each subsequent stage of mixing is reduced by 2% compared to the previous stage.

[0099] Example 10

[0100] This embodiment is basically the same as Embodiment 2, except that the proportion of alumina powder in each subsequent stage of mixing is reduced by 4% compared to the previous stage.

[0101] Example 11

[0102] This embodiment is basically the same as embodiment 2, except that the printing layer thickness is t = 0.6 mm.

[0103] Example 12

[0104] This embodiment is basically the same as embodiment 2, except that the printing layer thickness is t = 1 mm.

[0105] Example 13

[0106] This embodiment is basically the same as Embodiment 2, except that the heating curve of the sintering furnace heating process is as follows: the temperature is increased to 800°C at a rate of 10°C / min, then increased to 1400°C at a rate of 6°C / min, then increased to 1800°C at a rate of 3°C / min and held for 1 hour, then increased to 2000°C at a rate of 0.5°C / min and held for 6 hours before being taken out of the furnace and cooled.

[0107] Example 14

[0108] This embodiment is basically the same as Embodiment 2, except that the heating curve of the sintering furnace heating process is as follows: the temperature is increased to 900°C at a rate of 15°C / min, then increased to 1500°C at a rate of 8°C / min, then increased to 1900°C at a rate of 5°C / min and held for 2 hours, then increased to 2200°C at a rate of 2°C / min and held for 8 hours before being taken out of the furnace and cooled.

[0109] Experimental Example

[0110] The performance of the aluminum alloy connecting bases prepared in the above embodiments was tested to investigate the performance of the connecting bases prepared by the molds in each embodiment.

[0111] 1. Investigate the influence of silicon carbide powder and alumina powder parameters on the performance of the connecting base.

[0112] Using Examples 2, 3, and 4 as comparative experiments, and with Example 2 as a reference, a mixed powder was directly prepared by mixing 5μm-400μm silicon carbide powder and 5μm-300μm alumina powder as Comparative Example 1. The performance of the connecting base under different parameters of silicon carbide powder and alumina powder is shown in Table 1 below:

[0113] Table 1 Performance of connecting bases under different parameters for silicon carbide powder and alumina powder

[0114] Group Tensile strength (MPa) elongation Example 2 546 24.5％ Example 3 528 22.8％ Example 4 531 23.4％ Comparative Example 1 508 21.2％

[0115] As shown in Table 1, compared with Examples 2, 3, and 4, the connecting base of Example 2 has the highest tensile strength and elongation, indicating that the mold prepared in Example 2 has the best performance and the parameters of silicon carbide powder and alumina powder selected in Example 2 are optimal. Compared with Comparative Example 1, the connecting base of Example 2 has higher tensile strength and elongation, indicating that the mold prepared in Example 2 has the best performance and the mixing method of alumina powder and silicon carbide powder selected in Example 2 is better.

[0116] 2. Investigate the effect of powder mixing time on the performance of the connecting base.

[0117] Using Examples 2, 5, and 6 as experimental comparisons, the performance of the connecting base under different powder mixing times is shown in Table 2 below:

[0118] Table 2 Performance of the connecting base under different mixing times

[0119] Group Tensile strength (MPa) elongation Example 2 546 24.5％ Example 5 535 24.1％ Example 6 548 24.6％

[0120] As shown in Table 2, compared with Examples 2 and 5, the connecting base of Example 2 has the highest tensile strength and elongation, indicating that the mold performance of Example 2 is the best and the powder mixing time selected in Example 2 is more optimal. Compared with Examples 2 and 6, although the connecting base performance of Example 6 is better than that of Example 2, the performance improvement is not significant. Considering the time cost, the powder mixing time selected in Example 2 is more optimal.

[0121] 3. Investigate the effect of the proportion of alumina powder in the first-stage mixed powder on the performance of the connecting base.

[0122] Using Examples 2, 7, and 8 as comparative experiments, the performance of the connecting base under different proportions of alumina powder in the first-stage mixed powder is shown in Table 3 below:

[0123] Table 3. Performance of the connecting base under different alumina powder proportions in the first-grade mixed powder.

[0124] Group Tensile strength (MPa) elongation Example 2 546 24.5％ Example 7 531 23.3％ Example 8 535 23.6％

[0125] As shown in Table 3, the connecting base of Example 2 has the highest tensile strength and elongation, indicating that the mold prepared in Example 2 has the best performance and the proportion of alumina powder in the first-stage mixed powder selected in Example 2 is optimal.

[0126] 4. Investigate the effect of changes in the proportion of alumina powder in the mixed powder on the performance of the connecting base.

[0127] Using Examples 2, 9, and 10 as comparative experiments, and with Example 2 as a reference, and keeping the proportion of different alumina powders in the mixed powder constant as Comparative Example 2, the performance of the connecting base under different proportions of alumina powders in the mixed powder is shown in Table 4 below:

[0128] Table 4. Performance of the connecting base under different proportions of alumina powder in the mixed powder.

[0129]

[0130]

[0131] As shown in Table 4, compared with Examples 2, 9, and 10, the connecting base of Example 2 has the highest tensile strength and elongation, indicating that the mold prepared in Example 2 has the best performance and the change in the proportion of alumina powder in the mixed powder selected in Example 2 is optimal. Compared with Comparative Example 2, the connecting base of Example 2 has higher tensile strength and elongation, indicating that the mold prepared in Example 2 has the best performance and the change in the proportion of alumina powder selected in Example 2 is better.

[0132] 5. Investigate the effect of print layer thickness on the performance of the connecting base.

[0133] Using Examples 2, 11, and 12 as comparative experiments, the performance of the connecting base under different printing layer thicknesses is shown in Table 5 below:

[0134] Table 5 Performance of the connecting base under different print layer thicknesses

[0135] Group Tensile strength (MPa) elongation Example 2 546 24.5％ Example 11 531 23.2％ Example 12 528 23.0％

[0136] As shown in Table 5, the connecting base of Example 2 has the highest tensile strength and elongation, indicating that the mold prepared in Example 2 has the best performance and the printing layer thickness selected in Example 2 is optimal.

[0137] 6. Investigate the influence of the performance of the connecting base on the heating curve of the sintering furnace.

[0138] Using Examples 2, 13, and 14 as comparative experiments, and Example 2 as a reference, the heating rate was 7℃ / min throughout the entire process, serving as Comparative Example 3. The performance of the connecting base under different heating curves is shown in Table 6 below:

[0139] Table 6 Performance of the connecting base under different heating curves

[0140] Group Tensile strength (MPa) elongation Example 2 546 24.5％ Example 13 527 22.8％ Example 14 533 23.4％ Comparative Example 3 498 21.0％

[0141] As shown in Table 6, compared with Examples 2, 13, and 14, the connecting base of Example 2 has the highest tensile strength and elongation, indicating that the mold prepared in Example 1 has the best performance and the heating curve selected in Example 2 is the best. Compared with Comparative Example 3, the connecting base of Example 2 has higher tensile strength and elongation, indicating that the mold prepared in Example 2 has the best performance and the heating method selected in Example 2 is better.

Claims

1. A deformation-resistant casting mold for aerospace connecting bases, characterized in that, The mold consists of an upper mold (1) and a lower mold (2). The lower mold (2) is provided with a cavity (22) for filling molten metal. The upper mold (1) is provided with a core (11) for cooperating with the cavity (22). The upper mold (1) is provided with a gate (12) for pouring molten metal into the cavity (22). The lower mold (2) has multiple striking mechanisms (4) arranged circumferentially on its side wall, and the striking mechanisms (4) are slidably connected to the vertical grooves provided on the lower mold (2); A rotating ring (3) is rotatably connected to the lower mold (2). The rotating ring (3) has staggered peaks (31) and valleys (37). The peaks (31) contact the striking mechanism and are used to push the striking mechanism (4) to move upward to the top of the vertical groove. The valleys (37) are separated from the striking mechanism (4) located at the bottom of the vertical groove. A driving mechanism for driving the rotating ring (3) to rotate is provided on the side wall of the lower mold (2). Each of the wave crests (31) and the rotating rings (3) on both sides of the wave crests (31) are provided with multiple pressure columns (34) for contacting the striking mechanism (4) to squeeze. The rotating rings (3) are provided with vertical countersunk holes that correspond one-to-one with the pressure columns (34) and are slidably sealed. The pressure columns (34) and the vertical countersunk holes are connected by springs. The inner wall of the rotating ring (3) is provided with a plurality of second striking rods (35) corresponding to a plurality of pressure columns (34). The inner wall of the rotating ring (3) is provided with transverse countersunk holes that are slidably sealed and connected to the second striking rods (35) in a one-to-one manner. The plurality of transverse countersunk holes are connected to the corresponding vertical countersunk holes, and both the transverse countersunk holes and the vertical countersunk holes are filled with hydraulic oil.

2. The anti-deformation aerospace connecting base casting mold according to claim 1, characterized in that, The lower mold (2) has a connecting plate (21) on its side wall. The driving mechanism includes a motor (36) fixedly mounted on the connecting plate (21), a first gear (32) fixedly mounted on the output shaft of the motor (36), and a gear ring (33) mounted on the rotating ring (3) and used to mesh with the first gear (32).

3. The anti-deformation aerospace connecting base casting mold according to claim 1, characterized in that, The striking mechanism includes a slider (41) slidably connected to a vertical slide groove, a rotating disk (42) rotatably disposed on the slider (41) and used to contact and cooperate with the rotating ring (3) to move upward, a fixed rod (43) fixedly disposed on the rotating disk (42), and a first striking rod (44) slidably disposed on the fixed rod (43). The rotating disk (42) is rotatably connected to the slider (41) via a rotating shaft fitted with a torsion spring; one end of the first striking rod (44) contacts the side wall of the lower mold (2), and the other end of the first striking rod (44) passes through the fixed rod (43). A first limiting ring (46) is fixedly fitted on the first striking rod (44) on one side of the fixed rod (43), and the first limiting ring (46) is connected to the fixed rod (43) via a liquid bladder (47). A second limiting ring (48) is fixedly fitted on the first striking rod (44) on the other side of the fixed rod (43), and the second limiting ring (48) is connected to the fixed rod (43) via a spring. The lower mold (2) has multiple protrusions (45) on its side wall for swinging and engaging with the first striking rod (44) to strike. The first striking rod (44) has a liquid channel for applying lubricating oil to the protrusions (45), and the liquid channel is connected to the liquid bladder (47).

4. The anti-deformation aerospace connecting base casting mold according to claim 1, characterized in that, The lower mold (2) is provided with a positioning hole, and the upper mold (1) is provided with a positioning pin for cooperating with the positioning hole.

5. The anti-deformation aerospace connecting base casting mold according to claim 1, characterized in that, The top of the vertical slide is connected to the striking mechanism by a spring, and the striking mechanism is equipped with a counterweight.

6. The anti-deformation aerospace connecting base casting mold according to claim 3, characterized in that, The distance between any two adjacent pressure columns (34) on the rotating ring (3) is less than 1 / 2 of the single swing arc length of the rotating disk (42).

7. The anti-deformation aerospace connecting base casting mold according to claim 1, characterized in that, The method for preparing the lower mold (2) includes the following steps: S1, Take powder Take n grades of silicon carbide powder and n grades of alumina powder, where n is a natural number of 4≤n≤6. The particle size of silicon carbide powder gradually decreases as the grade increases, while the particle size of alumina powder gradually increases as the grade increases. The particle size of the n grades of silicon carbide powder is between 5μm and 400μm, and the particle size of the n grades of alumina powder is between 5μm and 300μm. S2, Mixed Powder Silicon carbide powder of different grades is mixed with alumina powder of corresponding grades to obtain mixed powders of different grades; wherein the alumina powder accounts for 50-60% of the first grade of mixed powder, and the alumina powder accounts for 2-4% less of each subsequent grade of mixed powder compared to the previous grade; S3, 3D printing The first-stage mixed powder is loaded into the 3DP printing equipment for layer-by-layer printing, where the thickness of each layer is t. After printing x layers, the next-stage mixed powder is used for printing until the blank of the lower mold (2) is printed. The value of x conforms to the following formula: Where h is the height of the lower mold (2), in mm; n is the grade of silicon carbide powder and alumina powder; 0.6≤t≤0.1, in mm; S4, sintering The blank is placed in a sintering furnace, and the furnace is gradually heated to 2000~2200℃. After holding at this temperature for 6~8 hours, the blank is removed from the furnace and cooled to obtain the lower mold (2).

8. The anti-deformation aerospace connecting base casting mold according to claim 7, characterized in that, In step S2, the powder is mixed using a ball mill with a ball-to-material ratio of 1:3 and a mixing time of 30-50 minutes.

9. A deformation-resistant aerospace connecting base casting mold according to claim 7, characterized in that, In step S4, the heating curve of the sintering furnace is as follows: the temperature is increased to 800-900℃ at a rate of 10-15℃ / min, then increased to 1400-1500℃ at a rate of 6-8℃ / min, then increased to 1800-1900℃ at a rate of 3-5℃ / min and held for 1-2 hours, and then increased to 2000-2200℃ at a rate of 0.5-2℃ / min.

10. A method for casting a deformation-resistant aerospace connecting base, based on a deformation-resistant aerospace connecting base casting mold according to any one of claims 1 to 9, characterized in that, Includes the following steps: S4-1. Place the metal raw material into the melting furnace for melting. After the metal raw material is melted into molten metal, let it stand for 2-5 minutes. Then close the upper mold (1) and the lower mold (2). Then start the drive mechanism to make the drive mechanism drive the rotating ring (3) to rotate. Pour the molten metal into the cavity (22) through the gate (12) for casting, so that the cavity (22) is filled with molten metal. S4-2. When the rotating ring (3) rotates, it will intermittently contact the striking mechanism (4), so that the striking mechanism (4) can slide up and down to guide the upper side wall of the lower mold (2) to strike in an up-and-down manner. At the same time, the striking mechanism (4) will intermittently squeeze the pressure column (34). S4-3, the pressure column (34) will descend and squeeze the hydraulic oil after being pressed. The second striking rod (35) will extend under the pressure of the hydraulic oil and rotate through the rotating ring (3) to perform a uniform ring-shaped knocking on the lower side wall of the lower mold (2), so that the molten metal can fill the gap in the cavity (22) under the vibration generated by the knocking. S4-4. Wait for the molten metal to solidify and take out the upper mold (1) to obtain the connecting base.

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