Friction stir deposition additive process capable of adaptively regulating and controlling forming stress

Abstract

The invention discloses a friction stir deposition additive process capable of adaptively regulating and controlling forming stress, which comprises the following steps of: assembling a stirring head on a main shaft of friction stir additive equipment, starting a main machine of the friction stir additive equipment, and setting process parameters; wherein the stirring head adopts a split type stirring head capable of regulating and controlling forming stress; starting a feeding mechanism, wherein the feeding mechanism is used for feeding powder materials required by material adding to the material adding area; and the stirring head is moved to the material adding starting point of the base plate, and material adding deposition is conducted in sequence according to the set mode. By the adoption of the scheme, the forming stress can be adjusted and controlled in a self-adaptive mode in the friction stir deposition material adding process, the whole powder deposition area can be covered with the self-adaptive adjustment and control area, edge materials generated by a shaft shoulder of the stirring head can be remarkably reduced, and accumulation is reduced; protruding edges formed by powder accumulation easily generated on the two sides of the front portion of the middle of the stirring head can be effectively prevented.

Description

Technical Field

[0001] The present invention belongs to the technical field of friction stir deposition additive manufacturing, and in particular relates to a friction stir deposition additive manufacturing process for adaptively regulating forming stress. Background Art

[0002] Existing document CN115178855B discloses a coaxial powder feeding friction stir additive manufacturing processing head, comprising a connecting part, a bearing connecting part, a rotating part and a stirring needle arranged in sequence from top to bottom; the bearing connecting part has a bearing outer ring, a bearing inner ring and a ball arranged between the bearing outer ring and the bearing inner ring; the bearing outer ring is provided with a first annular channel along the circumferential direction for receiving powder delivered from a powder feeding device; the connecting part is arranged to be fixedly connected to the bearing inner ring, and one end of the connecting part is arranged to receive a rotational driving force input, and the other end extends through the bearing inner ring of the bearing connecting part and is connected to the first end of the rotating part to drive the rotating part to be coaxial with the connecting part The stirring needle is arranged at the center position of the end surface of the second end of the rotating part, and the recessed part surrounds the stirring needle; the stirring needle extends in the direction away from the rotating part, and its bottom exceeds the end surface position of the second end of the rotating part; wherein, the rotating part is provided with an annular second channel running through from top to bottom along the circumferential direction, the upper end of the annular second channel is connected with the first channel, and the lower end is connected with the recessed part, thereby forming an annular powder feeding channel running through from top to bottom, which is configured to send the powder received from the annular first channel to the space of the recessed part via the annular second channel, so that the stirring needle can be processed and formed by friction stirring when the stirring needle rotates.

[0003] As previously mentioned, existing solutions for friction stir additive manufacturing (FSAM) employ a concave inner shoulder structure to facilitate the smooth accommodation of the additive material during deposition. However, this typical FSM has the problem of difficult-to-control forming stress during use. Furthermore, to achieve smooth FSM, the FSM head is typically tilted backward by approximately 3°, as required by standards. This inevitably leads to the accumulation of material, particularly on both sides of the front center of the head, where powder is prone to accumulating, forming ridges (ridges are the raised areas above the additive area). Summary of the Invention

[0004] At least in order to solve the technical problems mentioned in the background technology, the present invention aims to provide a stir friction deposition additive process that can adaptively control forming stress.

[0005] The present invention adopts the following technical solutions.

[0006] A friction stir deposition additive process for adaptively controlling forming stress, comprising: Step 1: Assemble a stirring head on the main shaft of the friction stir additive equipment, turn on the main unit of the friction stir additive equipment, and set the process parameters; wherein the stirring head adopts a split stirring head capable of regulating forming stress; Step 2: Start the feeding mechanism, which is used to feed the powder material required for the additive process into the additive area; Step 3: Move the stirring head to the additive starting point of the substrate and perform multiple passes of additive deposition in sequence according to the set method.

[0007] In order to reduce the accumulation of powder and the formation of ridges on both sides in front of the middle of the stirring head, the split stirring head includes a central rod body, a stirring needle is provided in the middle of the lower end of the central rod body, and several layers of coaxially arranged cylinders are sleeved on the central rod body and can move axially relative to the central rod body. The outer wall of the outermost cylinder is sleeved with a cylindrical shell, and any two adjacent cylinders are in contact with the wall. A material cavity is provided on the central rod body, and the material cavity is connected to the feeding pipe of the feeding mechanism; wherein, an elastic element is connected to the top of the cylinder, and the relative position of the central rod body and the cylindrical shell is always fixed; when the stirring head is in the initial state where additive deposition is not implemented, the lower ends of all cylinders, the lower end of the central rod body, and the cylindrical shell are located in the same horizontal plane; when the stirring head is in the process of implementing additive deposition, the lower ends of some cylinders are higher than the lower end of the central rod body.

[0008] Preferably, the elastic element adopts a plurality of coaxially arranged disc springs, and each disc spring matches a cylinder.

[0009] In order to implement the material addition more smoothly, an oil storage tank is provided on the outer wall of the cylinder.

[0010] In order to implement material addition more smoothly and stably, a guide protrusion is provided on the outer wall of the cylinder, and a guide groove is provided on the inner wall of the cylinder. The guide protrusions of two adjacent cylinders are gap-fitted in the guide groove.

[0011] In the present invention, during the additive deposition process according to the set method, the axis of the stirring head is always perpendicular to the surface of the substrate.

[0012] Preferably, the rotation speed of the stirring head is 1000-1500 r / min, and the travel speed of the stirring head is 800-1000 mm / min.

[0013] Preferably, the wall thickness of each cylinder is 3-5 mm.

[0014] Beneficial effects: The solution of the present invention can not only adaptively control the forming stress during the stir friction deposition additive process, and the adaptive control area can cover the entire powder deposition area, but also significantly reduce the generation and accumulation of edge material on the shoulder of the stirring head, and can effectively prevent the accumulation of powder on both sides of the front middle of the stirring head to form ridges. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 Schematic diagram of the external structure of the split stirring head in Example 1 Figure 1 ; Figure 2 Schematic diagram of the external structure of the split stirring head in Example 1 Figure 2 ; Figure 3 Schematic cross-section of the split stirring head in Example 1; Figure 4 This is a schematic diagram of the disassembled state of the split stirring head in Example 1. DETAILED DESCRIPTION

[0016] The following is a clear and complete description of the technical solutions of the present invention in conjunction with the accompanying drawings. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention. Example 1

[0017] A stir friction deposition additive process with adaptively controlled forming stress adopts a split stirring head capable of regulating forming stress, combined with Figures 1 to 4As shown, the split stirring head includes a central rod body 5, a stirring needle 2 is provided at the middle of the lower end of the central rod body 5, and six layers of coaxially arranged cylinders 15 (including the first layer cylinder 6, the second layer cylinder 7, the third layer cylinder 8, the fourth layer cylinder 9, the fifth layer cylinder 10, and the sixth layer cylinder 11 arranged in sequence from the inside to the outside) are sleeved on the central rod body 5. The wall thickness of each cylinder 15 is 5 mm and the length is 15 cm. The outer wall of the outermost cylinder is sleeved with a cylindrical shell 12. Any two adjacent cylinders 15 are in contact with the wall (cooperation between adjacent cylinders 15). A material cavity is provided on the central rod body 5, and the discharge port 3 of the material cavity is located at the stirring needle. 2 side, the material cavity is connected to the feeding pipe of the feeding mechanism; wherein, an elastic element is connected to the top of the cylinder 15, and the relative position of the central rod 5 and the cylindrical shell 12 is always fixed; when the stirring head is in the initial state without implementing additive deposition, the lower ends of all cylinders 15, the lower ends of the central rod 5, and the cylindrical shell 12 are located at the same horizontal plane; when the stirring head is in the process of implementing additive deposition, the lower ends of some cylinders 15 are higher than the lower end of the central rod 5; the elastic element adopts six coaxially arranged disc springs 13, the wall thickness of the disc spring 13 is 3mm, the maximum compression amount of the disc spring 13 is 2.5mm, and each disc spring 13 matches one cylinder 15; an oil storage tank 14 is provided on the outer wall of the cylinder 15, The radius of the oil storage tank 14 is 1.5 mm, and the length of the oil storage tank 14 is 12 cm; a guide protrusion is also provided on the outer wall of the cylinder 15, and the length of the guide protrusion is 5 cm. The oil storage tank 14 is also used as a guide groove, and the guide protrusions of two adjacent cylinders 15 are gap-fitted in the guide groove. The oil storage tank 14 and one end of the guide protrusion are both located at the lower end of the cylinder 15. This specific structural arrangement and length of the oil storage tank 14 and the guide protrusion can not only smoothly realize the role of adaptively controlling the forming stress, but also prevent different cylinders 15 from rotating relative to each other, thereby facilitating the stable realization of additive manufacturing.

[0018] The steps of the friction stir deposition additive process in this embodiment include: Step 1: Assemble the stirring head on the main shaft of the friction stir additive equipment, turn on the main unit of the friction stir additive equipment, and set the process parameters; Step 2: Start the feeding mechanism, which is used to feed the powder material required for the additive process into the additive area; Step 3: Move the stirring head to the additive starting point of the substrate, and perform multiple passes of additive deposition in sequence according to the set method; during the additive deposition process according to the set method, the axis of the stirring head is always perpendicular to the surface of the substrate; wherein, the rotation speed of the stirring head is 1000~1500r / min, and the travel speed of the stirring head is 800~1000mm / min.

[0019] Comparative Example 1: A stir friction deposition additive process uses a traditional stirring head with a stirring needle (the stirring tool of document CN119077110A). During the additive deposition process according to the set method, the stirring head is tilted backward by 3°; the rotation speed and travel speed of the stirring head are the same as in Example 1.

[0020] Comparative Example 2: A stir friction deposition additive process uses a traditional stirring head with a stirring needle (the stirring tool in document CN115178855B). During the additive deposition process according to the set method, the axis of the stirring head is always perpendicular to the substrate surface; the rotation speed and travel speed of the stirring head are the same as in Example 1.

[0021] Comparative Example 3: A stir friction deposition additive process uses a traditional stirring head without a stirring needle (the stirring tool in document CN116834281A). During the additive deposition process according to the set method, the axis of the stirring head is always perpendicular to the substrate surface; the rotation speed and travel speed of the stirring head are the same as in Example 1.

[0022] In the application test scheme, additive manufacturing was performed on a 6061 aluminum alloy substrate using the methods described in Example 1 and the Comparative Example. The powder particle size used ranged from 15 to 53 μm, the additive sample was a single layer, and the additive region was 40 cm long. The stirring head rotated at 1200 rpm and traveled at 900 mm / min. Testing of the resulting additive samples revealed that: in Example 1, the additive region had no burrs, and the maximum ridge height along the additive region was no greater than 0.5 mm (i.e., the height difference between the edge and the center of the additive region was no greater than 0.5 mm). In Comparative Example 1, the total burr length along the additive region was 31 cm, and the maximum ridge thickness along the additive region was 3.2 mm. In Comparative Example 2, the total burr length along the additive region was 17 cm, and the maximum ridge thickness along the additive region was 2.2 mm. In Comparative Example 3, the total burr length along the additive region was 8 cm, and the maximum ridge thickness along the additive region was 2.5 mm.

[0023] In the embodiment, due to the use of a specific structure of the stirring head and the scheme in which the axis of the stirring head is always perpendicular to the substrate surface, the forming stress can be adaptively controlled during the stir friction deposition additive process, the adaptive control area can cover the entire powder deposition area, each cylinder can independently move axially after being compressed, and the additive process can be smoothly achieved when the lower ends of all cylinders, the lower ends of the central rod body, and the cylindrical shell are located at the same horizontal plane, significantly reducing the generation of edge material and accumulation of the stirring head shoulder, and effectively preventing the accumulation of powder on both sides of the middle front of the stirring head from forming ridges. Among them, the role of this multi-layer coaxial arrangement of cylinders includes repeatedly vertically rolling the plasticized material and adaptively adjusting the stress, promoting the uniform and slow radial expansion of the plasticized material, and preventing the plasticized material from rapidly expanding radially in a large block and non-uniform manner, thereby implementing the additive process more stably, smoothly, and evenly, and preventing the plasticized powder from accumulating to form ridges; one of the roles played by the cylindrical shell is to ensure that the additive layer is flat and smooth, further preventing the overflow of the plasticized material.

Claims

1. A friction stir deposition additive process with adaptively controlled forming stress, characterized in that the steps include: Step 1: Assemble a stirring head on the main shaft of the friction stir additive equipment, turn on the main unit of the friction stir additive equipment, and set the process parameters; wherein the stirring head adopts a split stirring head capable of regulating forming stress; Step 2: Start the feeding mechanism, which is used to feed the powder material required for the additive process into the additive area; Step 3: Move the stirring head to the additive starting point of the substrate and perform multiple passes of additive deposition in sequence according to the set method.

2. The friction stir deposition additive process according to claim 1, wherein: The split stirring head includes a central rod body, a stirring needle is provided in the middle of the lower end of the central rod body, and several layers of cylinders are coaxially arranged and can move axially relative to the central rod body. The outer wall of the outermost cylinder is provided with a cylindrical shell, and any two adjacent cylinders are in contact with the wall. A material cavity is provided on the central rod body, and the material cavity is communicated with the feeding pipe of the feeding mechanism; wherein, an elastic element is connected to the top of the cylinder, and the relative position of the central rod body and the cylindrical shell is always fixed; when the stirring head is in the initial state where additive deposition is not implemented, the lower ends of all cylinders, the lower end of the central rod body, and the cylindrical shell are located in the same horizontal plane; when the stirring head is in the process of implementing additive deposition, the lower ends of some cylinders are higher than the lower end of the central rod body.

3. The friction stir deposition additive process according to claim 2, wherein: The elastic element adopts a plurality of coaxially arranged disc springs, and each disc spring matches a cylinder.

4. The friction stir deposition additive process according to claim 3, wherein: An oil storage tank is provided on the outer wall of the cylinder.

5. The friction stir deposition additive process according to claim 4, characterized in that: A guide protrusion is provided on the outer wall of the cylinder, and a guide groove is provided on the inner wall of the cylinder. The guide protrusions of two adjacent cylinders are loosely fitted in the guide groove.

6. The friction stir deposition additive process according to claim 5, characterized in that: During the additive deposition process according to the set method, the axis of the stirring head is always perpendicular to the substrate surface.

7. The friction stir deposition additive process according to claim 6, characterized in that: The rotation speed of the stirring head is 1000-1500 r / min, and the travel speed of the stirring head is 800-1000 mm / min.

8. The friction stir deposition additive process according to claim 7, wherein: The wall thickness of each cylinder is 3~5mm.

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