An adaptive servo-driven rapid cooling device for solid-state additive manufacturing and its usage method

Abstract

This invention discloses an adaptive, servo-driven rapid cooling device and its usage method for solid-state additive manufacturing. The device includes a spindle, an upper cover base fitted onto the upper part of the spindle and not rotating with it, and a lower cover connected to the upper cover base via a cylinder. The lower cover is installed on the lower part of the spindle and can slide freely along the spindle axis. The sidewalls of the lower cover have inlets and outlets, and the interior of the lower cover has an integrated flow channel. The inlets and outlets are connected through the integrated flow channel. A sealing ring is provided at the bottom of the lower cover. The cylinder is initially in a compressed state, used to drive the lower cover to remain in close contact with the deposition surface. As the deposition height increases, the cylinder changes from a compressed state to an extended state, with the extension amount matching the spindle's lifting amount. This invention achieves efficient water cooling and full-path adaptive sealing in the forming area, significantly reducing the difference in thermal history between deposition areas at different heights and enabling rapid cooling during the solid-state additive manufacturing process, thus improving the microstructure uniformity of the solid-state additive parts.

Description

Technical Field

[0001] This invention relates to the field of solid-state additive manufacturing technology, and specifically to an adaptive servo-driven rapid cooling device and its usage method for solid-state additive manufacturing. Background Technology

[0002] Friction stir solid-state deposition (FSPD) is a novel additive manufacturing technology that uses frictional heat generated between a metal rod, powder, or filament and a substrate to induce a thermoplastic state, which is then extruded and deposited onto the substrate to form the first deposition layer. Subsequent deposition layers are then added to form a solid part. FPD not only boasts high deposition efficiency but also effectively avoids defects commonly found in traditional fused deposition modeling, such as porosity, hot cracking, and component segregation. However, conventional friction stir additive manufacturing faces significant challenges in thermal field control when cooled in air.

[0003] Firstly, there is the issue of thermal cycling and microstructure inhomogeneity: as the deposition height increases, the heat dissipation effect of the substrate gradually weakens. The bottom layer material, having undergone multiple long-term thermal cycles, is prone to the dissolution of the strengthening phase; while the top layer material, due to severe heat accumulation and extremely slow cooling, leads to grain coarsening. This significant difference in thermal cycling and heat accumulation results in substantial differences in microstructure and mechanical properties at different deposition heights, severely limiting the service reliability of large structural components.

[0004] In current technologies, the microstructure differences in friction stir solid additive parts are usually improved by post-heat treatment. However, while heat treatments such as solution treatment or homogenization treatment can improve the distribution differences of the reinforcing phase, they can hardly improve the differences in grain size at different heights. Summary of the Invention

[0005] Purpose of the invention: This invention proposes an adaptive rapid cooling device and method for solid-phase additive manufacturing, which can adaptively adjust with the deposition height and perform real-time cooling during the manufacturing process, thereby achieving consistency in cooling rate at different heights and reducing differences in thermal cycling.

[0006] Technical Solution: This invention proposes an adaptive rapid cooling device for solid-state additive manufacturing, comprising a spindle, an upper cover base disposed outside the spindle, and a lower cover; the upper cover base is connected to the upper end of the spindle via a connecting bearing, the lower cover has an internal cavity for axial movement of the spindle, and the lower cover is connected to the lower end of the upper cover base via a driving device; the lower cover includes an inner flow channel near the spindle, an outer flow channel located outside the inner flow channel, an inlet, and an outlet valve core; the inlet is located on the side wall of the lower cover and communicates with the outer flow channel, the outlet valve core is located at the bottom end of the side wall of the lower cover and communicates with the inner flow channel, the inner flow channel and the outer flow channel are connected by an inlet groove, the bottom end of the inner flow channel communicates with the cavity, and a sealing ring is provided at the bottom of the lower cover.

[0007] Preferably, the spindle has a feeding channel at its center.

[0008] Preferably, the upper sidewall of the main shaft is provided with a step that engages with the upper cover base.

[0009] Preferably, the upper cover base has a through hole at its center, the through hole is coaxial with the main shaft, and the connecting bearing is located inside the through hole of the upper cover base.

[0010] Preferably, the driving device consists of at least two cylinders, which are symmetrically arranged on both sides of the upper cover. The upper end of each cylinder is fixedly connected to the lower end of the upper cover base, and the lower end is fixedly connected to a fixing block on the side wall of the lower cover.

[0011] Preferably, the inner bottom end of the inner flow channel is provided with an opening for communicating with the cavity, and the outer bottom end of the inner flow channel is provided with a water outlet, which is connected to the water outlet valve core.

[0012] Preferably, the top surface of the water inlet tank is lower than the bottom edge of the water inlet.

[0013] Preferably, the lower cover is used to dock with the deposition substrate and a sealing ring is used to form a seal between the lower cover and the deposition substrate; the upper surface of the deposition substrate is lower than the water inlet tank.

[0014] A method of using an adaptive servo-driven rapid cooling device for solid-state additive manufacturing includes the following steps:

[0015] S1: The bar stock is loaded into the spindle, the cylinder is in the compression loading state, and the pressure control command is received to push the lower cover to move downward along the spindle axis, so that the sealing ring at the bottom of the lower cover presses against the surface of the deposition substrate.

[0016] S2: The spindle starts to rotate and causes the bar to rub against the deposition substrate. The bar enters a thermoplastic state and begins to be deposited and formed under the extrusion action. At this time, cooling water enters the outer flow channel through the water inlet, then enters the inner flow channel through the water inlet tank and flows to the cavity outside the forming area at the end of the spindle.

[0017] S3: After the first deposition layer in S2 is completed, the spindle is lifted upward along the axis according to the preset layer height. The cylinder extends to compensate for the displacement difference caused by the lifting of the spindle, ensuring that the sealing ring fits the deposition substrate surface.

[0018] S4: Repeat S2 and S3, the number of deposition layers continues to increase, the main shaft continues to rise gradually according to the layer height, the cylinder gradually changes from the initial compression state to the extension state, the cylinder extension amount matches the main shaft lifting amount, and the water level in the cavity gradually increases with the increase of deposition height, so that the cooling water level in the central area of ​​the cavity matches the current total deposition layer height, and at the same time the outlet valve core starts to drain water, forming a water circulation in the cavity;

[0019] S5: After all the deposition layers are completed, stop feeding and spindle rotation, and keep the cooling water circulating until the temperature of the forming area drops to room temperature. Stop injecting cooling water and completely discharge it through the outlet valve core. The cylinder contracts, causing the lower cover to move upward, the sealing ring to separate from the deposition substrate, the spindle is lifted as a whole, and the solid phase additive manufacturing sample after deposition and cooling is taken out.

[0020] Preferably, in S3, the single lifting height of the main shaft and the single extension of the cylinder are determined by the height of the single-layer deposition layer.

[0021] Beneficial Effects: Compared to existing technologies where rapid cooling in friction-stirred solid-phase additive manufacturing is often achieved in a fixed water tank, making rapid water circulation difficult, this invention utilizes the combination of internal and external flow channels and the design of inlet and outlet valve cores. This enables efficient water cooling of the forming area and adaptive sealing throughout the entire process, significantly reducing the differences in thermal history between deposition areas at different heights and achieving rapid cooling during solid-phase additive manufacturing. Because the forming area is constantly surrounded by cooling water, the bottom layer material no longer undergoes prolonged high-temperature thermal cycling, effectively suppressing the coarsening of the reinforcing phase. Furthermore, the top area does not experience a decrease in cooling rate due to heat accumulation, thus preventing grain coarsening and greatly improving microstructure uniformity and grain refinement. This invention also achieves seamless, follow-up sealing of deposition surfaces at different heights and with localized unevenness through a coupled design of "cylinder-driven lower cover movement + bottom sealing ring." Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the overall structure of the adaptive rapid cooling device of the present invention;

[0023] Figure 2This is a cross-sectional view of the cylinder of the adaptive follow-up rapid cooling device of the present invention, including the valve core with inlet and outlet water in the initial state.

[0024] Figure 3 This is a cross-sectional view of the cylinder in the initial state of the adaptive follow-up rapid cooling device of the present invention;

[0025] Figure 4 This is a cross-sectional view of the inlet and outlet valve cores of the adaptive follow-up rapid cooling device of the present invention in the extended state of the cylinder.

[0026] Figure 5 This is a cross-sectional view of the cylinder in the extended state of the adaptive follow-up rapid cooling device of the present invention.

[0027] Figure 6 This is a half-sectional view of the cylinder of the adaptive rapid cooling device of the present invention, including the valve core with inlet and outlet in the initial state.

[0028] Figure 7 This is a half-sectional view of the cylinder in the initial state of the adaptive follow-up rapid cooling device of the present invention.

[0029] Figure 8 This is a half-sectional view of the inlet and outlet valve cores of the self-adaptive rapid cooling device of the present invention in the extended state of the cylinder.

[0030] Figure 9 This is a half-sectional view of the cylinder in the extended state of the adaptive follow-up rapid cooling device of the present invention.

[0031] Figure 10 This is a schematic diagram of the cooling device of the present invention in use. Detailed Implementation

[0032] like Figures 1 to 10 As shown in the accompanying drawings, the present invention will be described in further detail.

[0033] An adaptive follow-up rapid cooling device for solid-phase additive manufacturing includes a main shaft 101 with a central feeding channel 102, an upper cover base 202 sleeved on the upper end of the main shaft 101, a lower cover 3 connected to the upper cover base 202 via a cylinder 4, the lower cover 3 being located outside the main shaft 101 and below the upper cover base 202, and a sealing ring 5 at the bottom of the lower cover 3, the sealing ring 5 being made of flexible material and having a multi-layer sealing structure. The central through hole of the upper cover base 202 is coaxially arranged with the main shaft 101. A connecting bearing 201 is provided at the central through hole of the upper cover base 202. The upper cover base 202 is connected to the main shaft 101 through the connecting bearing 201. When the main shaft 101 rotates at high speed under power drive to generate frictional heat, the connecting bearing 201 can release the rotational degree of freedom, so that the upper cover base 202 always remains in a non-rotating static state. The upper cover base 202 serves as an installation platform for external pipelines and power mechanisms.

[0034] The lower cover 3 has symmetrical fixing blocks 308 on its side wall. The upper end of the cylinder 4 is connected to the upper cover base 202 by bolts, and the lower end of the cylinder is connected to the fixing blocks 308 on the side wall of the lower cover 3 by bolts, so as to ensure that the upper and lower covers are independent of the main shaft 101. The cylinder 4 is used to drive the lower cover 3 to move along the axis of the main shaft 101. The lower cover 3 has a cavity 307 in the center for the main shaft 101 to move axially. The side wall of the lower cover 3 has an outer flow channel 305 and an inner flow channel 306. The upper end of one side wall of the lower cover has a water inlet 301, and the bottom end of the other side wall has a water outlet valve core 304. The water inlet 301 is connected to the outer flow channel 305. The outer flow channel 305 is connected to the inner flow channel 306 through the water inlet groove 302. The bottom end of the inner side of the inner flow channel 306 has an opening that is connected to the cavity 307. The bottom end of the outer side of the inner flow channel 306 has a water outlet 303. The water outlet valve core 304 is connected to the inner flow channel 306 through the water outlet 303. The water inlet 301 and the water outlet valve core 304 are distributed opposite to each other to prevent the cooling water from being discharged before entering the cavity 307.

[0035] The top of the inlet tank 302 is lower than the bottom edge of the inlet 301. It employs a separate outer and inner flow channel design. Cooling water first enters the outer flow channel 305 through the inlet 301. When the water level in the outer flow channel 305 exceeds that of the inlet tank 302, the cooling water enters the inner flow channel 306 and flows towards the central area of ​​the cavity 307. The design of the inner and outer flow channels ensures a stable injection of cooling water and avoids splashing, which could affect the deposition process. By adjusting the water inlet speed, the inlet 301 is connected to an external water supply pipeline, which is equipped with a circulating water pump and a flow regulating valve. By adjusting the speed of the circulating water pump or the opening of the flow regulating valve, the flow rate of cooling water entering the inlet 301 per unit time is changed, thereby regulating the water inlet speed and consequently controlling the water level and water circulation speed in the central area.

[0036] A method of using an adaptive servo-driven rapid cooling device for solid-state additive manufacturing includes the following steps:

[0037] S1: Fix the deposition substrate 6 on the worktable and load the bar stock 7 into the feeding channel 102 of the spindle 101. At this time, the cylinder 4 is in the compression loading state and receives the pressure command to push the cover 3 to move downward, so that the sealing ring 5 presses against the surface of the deposition substrate.

[0038] S2: The spindle 101 starts to rotate and drives the bar 7 to rub against the deposition substrate 6. The bar 7 enters the thermoplastic state and begins to be deposited and formed under the extrusion action. At this time, cooling water enters the outer channel 305 through the water inlet 301. When the water level in the outer channel 305 reaches the preset height, it enters the inner channel 306 through the water inlet 302 and flows into the cavity 307 outside the forming area at the end of the spindle 101.

[0039] S3: After the deposition in S2 is completed, the main shaft 101 is lifted upward along the axis according to the preset layer height. The cylinder 4 extends to compensate for the displacement difference caused by the lifting of the main shaft 101, ensuring that the sealing ring 5 fits the surface of the deposition substrate. The lower cover 3 and the main shaft 101 are kept motion decoupled. The lower cover 3 does not rotate with the main shaft 101, but always applies a stable downward pressing force to the surface of the deposition substrate 6 under the action of the cylinder 4.

[0040] S4: Repeating S2 and S3, the number of deposition layers continuously increases. The main shaft 101 is continuously raised upwards according to the layer height. The cylinder 4 gradually changes from the initial compression state to the extension state. The extension of the cylinder 4 matches the lifting amount of the main shaft 101, and the water level in the cavity 307 is gradually increased with the increase of deposition height, so that the cooling water level in the central area of ​​the cavity 307 matches the current total deposition layer height. At the same time, the outlet valve core 304 begins to discharge cooling water that has heated up due to the absorption of deposition heat, forming a water circulation in the cavity 307. Throughout the solid-phase additive manufacturing process, there is always flowing cooling water around the forming area. The cooling water achieves local forced cooling in the cavity near the forming area on the one hand, and continuously discharges the heated body through the outlet and replenishes low-temperature cooling water on the other hand, thus forming a stable water circulation heat exchange process. This process can significantly reduce heat accumulation during deposition, reduce the long-term thermal cycling experienced by the bottom material, and avoid grain coarsening of the top material due to insufficient heat dissipation, thereby improving the uniformity of the microstructure in different height areas.

[0041] S5: When all the deposition layers are completed, stop feeding and spindle 101 rotation, and keep cooling water circulating until the temperature of the forming area drops to room temperature. Stop injecting cooling water and completely discharge it through the outlet valve core 304. The cylinder 4 retracts, causing the lower cover 3 to move upward. The sealing ring 5 separates from the deposition substrate 6. The spindle 101 is lifted as a whole, and the solid phase additive manufacturing sample after deposition and cooling is taken out.

[0042] This invention solves the problem of varying cooling rates at different heights of the deposited layer caused by thermal cycling during friction stir solid-state additive manufacturing by precisely coupling the lower cover and sealing ring with a cylinder. Adjustable water inlet / outlet control enables real-time forced quenching of the processing zone, effectively suppressing heat accumulation and prolonged high-temperature thermal cycling effects during additive manufacturing. This fundamentally addresses the technical challenges of coarsening of the bottom reinforcing phase and uneven grain size at the top, significantly improving the uniformity of the microstructure and the refinement of the grains throughout the entire process of the formed part.

Claims

1. A self-adaptive rapid cooling device for solid-state additive manufacturing, characterized in that, The device includes a main shaft (101), an upper cover base (202) disposed outside the main shaft (101), and a lower cover (3); the upper cover base (202) is connected to the upper end of the main shaft (101) via a connecting bearing (201); the lower cover (3) has a cavity (307) inside for axial movement of the main shaft (101); the lower cover (3) is connected to the lower end of the upper cover base (202) via a driving device; the lower cover (3) includes an inner flow channel (306) near the main shaft (101), and a lower flow channel (307) located in the inner flow channel (306). 06) The outer flow channel (305), the inlet (301) and the outlet valve core (304) are located on the side wall of the lower cover (3) and are connected to the outer flow channel (3022). The outlet valve core (304) is located at the bottom of the side wall of the lower cover (3) and is connected to the inner flow channel (3021). The inner flow channel (3021) and the outer flow channel (3022) are connected through the inlet groove (302). The bottom of the inner flow channel (306) is connected to the cavity (307). The bottom of the lower cover (3) is provided with a sealing ring (5).

2. The adaptive fast cooling device for solid-state additive manufacturing according to claim 1, characterized in that, The main shaft (101) has a feeding channel (102) at its center.

3. The adaptive fast cooling device for solid-state additive manufacturing according to claim 1, characterized in that, The upper side wall of the main shaft (101) is provided with a step that engages with the upper cover base (202).

4. The adaptive fast cooling device for solid-state additive manufacturing according to claim 3, characterized in that, The upper cover base (202) has a through hole at its center, the through hole is coaxial with the main shaft (101), and the connecting bearing (201) is located inside the through hole of the upper cover base (202).

5. The adaptive fast cooling device for solid-state additive manufacturing according to claim 1, characterized in that, The driving device consists of at least two cylinders (4), which are symmetrically arranged on both sides of the upper cover (3). The upper end of the cylinder (4) is fixedly connected to the lower end of the upper cover base (202), and the lower end is fixedly connected to the fixing block (308) on the side wall of the lower cover (3).

6. The adaptive fast cooling device for solid-state additive manufacturing according to claim 1, characterized in that, The inner bottom of the inner flow channel (306) is provided with an opening for communicating with the cavity (307), and the outer bottom of the inner flow channel (306) is provided with a water outlet (303), which is connected to the water outlet valve core (304).

7. The adaptive fast cooling device for solid-state additive manufacturing according to claim 1, characterized in that, The top surface of the water inlet trough (302) is lower than the bottom edge of the water inlet (301).

8. The adaptive fast cooling device for solid-state additive manufacturing according to claim 1, characterized in that, The lower cover (3) is used to dock with the deposition substrate (6) and a sealing ring (5) is used to form a seal between the lower cover (3) and the deposition substrate (6); the upper surface of the deposition substrate (6) is lower than the water inlet tank (302).

9. A method of using the adaptive servo-driven rapid cooling device for solid-state additive manufacturing according to any one of claims 1-8, characterized in that, Includes the following steps: S1: Insert the bar stock (7) into the spindle (101), and the cylinder (4) is in a compression loading state. Receive the pressure control command to push the lower cover (3) to move downward along the axis of the spindle (101), so that the sealing ring (5) at the bottom of the lower cover presses against the surface of the deposition substrate (6). S2: The spindle (101) starts to rotate and drives the bar to rub against the deposition substrate (6). The bar enters a thermoplastic state and begins to be deposited and formed under the extrusion action. At this time, cooling water enters the outer flow channel (305) through the water inlet (301), and then enters the inner flow channel (306) through the water inlet (302) and flows to the cavity (307) outside the forming area at the end of the spindle (101). S3: When the first deposition layer in S2 is completed, the spindle (101) is raised along the axis according to the preset layer height, and the cylinder (4) is extended to compensate for the displacement difference caused by the lifting of the spindle (101) and ensure that the sealing ring (5) fits the surface of the deposition substrate (6). S4: Repeat S2 and S3, the number of deposition layers increases continuously, the main shaft (101) continues to rise gradually according to the layer height, the cylinder (4) gradually changes from the initial compression state to the extension state, the extension of the cylinder (4) matches the lifting amount of the main shaft (101), and gradually increases the water level in the cavity (307) as the deposition height increases, so that the cooling water level in the central area of ​​the cavity (307) matches the current total deposition layer height, and at the same time the outlet valve core (304) starts to drain water, forming a water circulation in the cavity (307); S5: When all the deposition layers are completed, stop feeding and spindle (101) rotation, and keep the cooling water circulating until the temperature of the forming area drops to room temperature. Stop injecting cooling water and completely discharge it through the outlet valve core (304). The cylinder (4) contracts and drives the lower cover (3) to move up. The sealing ring (5) separates from the deposition substrate (6). The spindle (101) is lifted as a whole, and the solid phase additive manufacturing sample after deposition and cooling is taken out.

10. The method of using the adaptive servo-driven rapid cooling device for solid-state additive manufacturing according to claim 8, characterized in that, The single lifting height of the main shaft (101) and the single extension of the cylinder (4) in S3 are determined by the height of the single-layer deposition layer.

Images