An additive manufacturing apparatus and manufacturing method based on powder feeding and stirring friction deposition.

Abstract

This invention discloses an additive manufacturing apparatus and method based on powder feeding and friction stirring deposition. It includes an extrusion device, a rotary-thrust coupling, a drive shaft, an extrusion rod, a connecting shaft, a powder feeding sleeve, a cutter holder, and a stirring head. The extrusion device provides the extrusion force required for powder compaction and extrusion. The rotary-thrust coupling transmits thrust to the rotating drive shaft. The drive shaft performs axial movement and transmits thrust. The extrusion rod compacts and extrudes the powder. The connecting shaft transmits torque to the drive shaft. The powder feeding sleeve provides a channel for powder transport. The cutter holder transmits torque from the main shaft to the stirring head and the connecting shaft. The stirring head performs friction stirring deformation on the compacted powder and the added layer. The additive manufacturing method consists of the steps of starting, powder feeding, compaction, extrusion and friction stirring, and extrusion rod retraction. This invention enables relatively dense powder extrusion, ensures smooth transmission of extrusion force to the powder, and provides more precise control of powder flow rate, force, and temperature during the processing.

Description

Technical Field

[0001] This invention belongs to the field of friction stir additive manufacturing, and relates to a powder-feeding friction stir deposition additive manufacturing device and method. Background Technology

[0002] Metal additive manufacturing can be divided into two main categories: molten additive manufacturing and solid-state additive manufacturing. For molten additive manufacturing, the base metal is prone to defects such as cracks and voids during solidification. Especially for large components, hot isostatic pressing or micro-area deformation is often required to meet the actual requirements. Common solid-state additive manufacturing processes include cold spray metal printing and ultrasonic consolidation, which have largely eliminated most voids and cracks. However, they still have the problem of insufficient interfacial bonding. Based on these issues, friction stir additive manufacturing technology has been developed to directly manufacture metal components. Parts obtained by this method have advantages such as low residual stress and fine grain size.

[0003] For friction stir additive manufacturing, the mainstream forms can be divided into two main categories: FSAM (Fiction Stir Additive Manufacturing), which is based on traditional friction stir butt joints and overlaps, and AFSD (Additive Fiction Stir Deposition), which is based on hollow spindle feeding deposition. AFSD can be further divided into rod-feeding type and powder-feeding type according to the type of filler. Among them, powder-feeding AFSD has a wider range of adjustable powder properties, and the components manufactured using it have a broader range of performance applications.

[0004] For powder-fed AFSD (Anaerobic Friction Stirring Additive Manufacturing), the challenge lies in densifying loose powder through pressure and agitation friction while preventing powder blockage at the shoulder outlet. For example, the literature [CIRP Journal of Manufacturing Science and Technology 38(2022)252–267] reports a method for additive manufacturing of aluminum alloy blocks by using gas pressure to deliver powder to a hollow stirring head; however, macroscopic sample observation and microstructure analysis show that a large amount of unbonded material still exists inside the resulting block. Patent CN115178855A reports a coaxial powder-fed friction stir additive manufacturing head, system, and additive manufacturing method, which designs a top-down annular powder feeding channel inside the stirring head; however, this design easily leads to powder blockage at the outlet end. Patent CN111804910A reports a method and apparatus for additive manufacturing of nano-reinforced matrix composites by friction stir forging. The apparatus uses a screw to transport and extrude powder. However, this design ignores the fact that when the powder is extruded into a block, the stirring head will transmit non-uniform torque to the alloy block and eventually act on the screw. This will cause the screw to undergo elastic deformation and contact the screw sleeve, resulting in premature failure under intense friction. Summary of the Invention

[0005] To address the aforementioned problems in the prior art, this invention provides a powder-feeding stirred friction deposition additive manufacturing device and method.

[0006] The complete technical solution of this invention includes:

[0007] An additive manufacturing apparatus based on powder-feeding friction stir deposition includes, from top to bottom, an extrusion device 1, a rotary-thrust coupling 2, a drive shaft 3, an extrusion rod 8, a connecting shaft 4, a powder feeding sleeve 5, a cutter holder 6, and a stirring head 7.

[0008] The extrusion device 1 is used to provide the extrusion force required for the powder compaction and extrusion process;

[0009] The rotary-thrust coupling 2 is used to transmit thrust to the rotating drive shaft 3;

[0010] The drive shaft 3 performs axial movement and transmits thrust.

[0011] The connecting shaft 4 is used to transmit torque to the drive shaft 3;

[0012] The powder feeding sleeve 5 is used to provide a channel for powder conveying;

[0013] The handle 6 is used to transmit the torque of the main shaft to the stirring head 7 and the connecting shaft 4;

[0014] The stirring head 7 is used to stir and deform the compacted powder and the additive layer by friction.

[0015] The extrusion rod 8 compresses and densifies the powder during the additive manufacturing process, and the powder is eventually squeezed into the stirring friction zone.

[0016] Furthermore, the extrusion rod 8 is threaded to the drive shaft 3, and the outer diameter of its extrusion end matches the size of the hollow channel in the stirring head.

[0017] Furthermore, the stirring head is threadedly connected to the lower part of the connecting knife handle. The stirring head consists of a shoulder (or stirring teeth), a hollow channel, and a connecting thread. The hollow channel is used to transport powder and compact it under the action of extrusion pressure. The shoulder and stirring teeth are used to generate frictional heat and promote plastic flow.

[0018] The drive shaft can move up and down while rotating synchronously, and can transmit compressive force.

[0019] The rotary-extrusion connection device can transmit the extrusion force provided by the extrusion device to the rotating drive shaft. Its structure mainly includes a pair of couplings and a pair of bearings that provide axial thrust placed in the middle.

[0020] The extrusion device consists of a servo motor, a reducer, and an electric cylinder, which can precisely control its up-and-down movement speed.

[0021] The powder feeding device uses gas to feed the powder and is connected by a flexible hose.

[0022] Furthermore, the extrusion device 1 is fixed on the frame and does not rotate during the additive manufacturing process.

[0023] Furthermore, the extrusion device is an electric push rod, a hydraulic push rod, or a pneumatic push rod.

[0024] Furthermore, the drive shaft 3, extrusion rod 8, connecting shaft 4, tool holder 6, and stirring head 7 are always rotating at the same speed during the additive manufacturing process.

[0025] Furthermore, the connecting shaft 4 can transmit torque to the transmission shaft 3 through splines, flat keys, or other means, thereby achieving rotation at the same speed.

[0026] Furthermore, the friction zone 733 of the stirring head 7 has a certain geometric shape.

[0027] Furthermore, the geometry of the friction zone is vortex-shaped, spiral-shaped, tooth-shaped, or groove-shaped.

[0028] The additive manufacturing method using the aforementioned apparatus for powder feeding and friction stirring deposition consists of five steps: startup, powder feeding, compaction, extrusion and friction stirring, and extrusion rod retraction. Specifically, it includes:

[0029] (1) Start-up: Start the spindle, the stirring head rotates, and move the XYZ axes of the machine tool to make the stirring head contact the substrate;

[0030] (2) Powder feeding: The powder is conveyed to the hollow channel of the stirring head through the powder feeding device;

[0031] (3) Compact: The powder is rapidly cold-pressed under the action of the extrusion rod;

[0032] (4) Extrusion and stirring friction: The powder is extruded by the extrusion rod and the powder is formed and the interlayer metallurgical bonding of the additive manufacturing is achieved through stirring friction;

[0033] (5) Extrusion rod retraction: The extrusion rod retracts to the initial position.

[0034] Furthermore, the substrate is preheated by contact between the stirring head 7 and the substrate to meet the powder forming requirements, while providing a closed space for powder extrusion.

[0035] Furthermore, during the compaction process, the extrusion rod is pressed down rapidly, and the compaction process is controlled based on the motor torque or gas / liquid pressure feedback.

[0036] Furthermore, the downward pressing speed of the extrusion rod should match the machine tool's moving speed and satisfy formula (1):

[0037]

[0038] In the formula, v1 is the downward pressing speed of the extrusion rod, in mm / min, and v2 is the machine tool moving speed, in mm / min.

[0039] The diameter of the hollow channel in stirring head 7 is in mm. d is the shoulder diameter of the stirring head in mm; d is the thickness of the additive layer per pass in mm; k is the powder density under the current pressure, which is a function of the extrusion rod pressure.

[0040] Furthermore, before starting actual additive manufacturing, the density of the powder under different pressures should be tested to obtain the powder pressure-density function equation, that is, the function equation of powder pressure and k, and the density k under a certain pressure should be determined accordingly.

[0041] Furthermore, a temperature sensor and an infrared temperature probe are installed on the substrate to automatically adjust the rotation speed and movement speed of the stirring head based on temperature feedback.

[0042] Furthermore, when the measured pressure data or the required moving speed changes, the pressing speed of the extrusion rod is automatically controlled by feedback according to formula (1).

[0043] The beneficial effects of this invention compared to the prior art are as follows:

[0044] (1) It can achieve relatively dense extrusion of powder and the powder will not clog at the mixing head.

[0045] (2) The extrusion rod and the hollow main shaft rotate at the same speed, the fit between the extrusion rod and the hollow channel can be further improved, and its rigidity is significantly increased. The central axis of the component parts is easier to be aligned, so that the extrusion pressure can be smoothly transmitted to the powder, and the probability of the material "collapses" is significantly reduced.

[0046] (3) Feedback control is adopted to make the powder flow rate, force and temperature control more precise during the processing. Attached Figure Description

[0047] To more clearly illustrate the content and specific embodiments of this invention, the accompanying drawings required for the description process are introduced. The following drawings are merely for the purpose of illustrating the subject matter of this invention. Those skilled in the art can readily provide other similar drawings based on the drawings in this invention without any inventive effort.

[0048] Figure 1 This is a schematic diagram of the overall structure of the powder-feeding stirred friction deposition additive manufacturing device of the present invention.

[0049] Figure 2 This is a cross-sectional schematic diagram of the rotary-thrust coupling of the powder-feeding stirred friction deposition additive manufacturing device of the present invention.

[0050] Figure 3 This is a schematic diagram of the tool holder of the powder-feeding stirred friction deposition additive manufacturing device of the present invention.

[0051] Figure 4 This is a schematic diagram of the drive shaft of the powder-feeding stirred friction deposition additive manufacturing device of the present invention.

[0052] Figure 5 This is a schematic diagram of the connecting shaft of the powder-feeding stirred friction deposition additive manufacturing device of the present invention.

[0053] Figure 6 This is a schematic diagram of the powder feeding sleeve of the powder feeding type stirred friction deposition additive manufacturing device of the present invention.

[0054] Figure 7 This is a schematic diagram of the stirring head of the powder-feeding stirring friction deposition additive manufacturing device of the present invention.

[0055] Figure 8 This is a schematic diagram of the process of the additive manufacturing method based on powder feeding and stirring friction deposition according to the present invention.

[0056] In the diagram: 1-Extrusion device, 2-Rotation-thrust coupling, 3-Drive shaft, 4-Connecting shaft, 5-Powder feeding sleeve, 6-Knife holder, 7-Stirring head, 8-Extrusion rod, 21-Upper coupling, 22-Lower coupling, 211-First thread, 212-First screw hole, 221-Double nut, 222-Second screw hole, 223-Tap roller bearing, 224-First sealing ring, 31-Locking thread, 32-Bearing mating surface, 33-External spline, 34-Internal thread, 41-Internal spline, 42-Powder feeding hole, 43-External thread, 51-Channel, 52-Second sealing ring, 61-Conical surface, 62-Third screw hole, 63-Second thread, 64-Third thread, 71-Connecting thread, 72-End face, 73-Shoulder, 732-Central hole, 733-Friction zone. Detailed Implementation

[0057] The present invention will now be described in detail with reference to embodiments and accompanying drawings. However, it should be understood that the embodiments and drawings are for illustrative purposes only and do not constitute any limitation on the scope of protection of the present invention. All reasonable modifications and combinations included within the inventive spirit of the present invention fall within the scope of protection of the present invention.

[0058] This invention first discloses a powder-feeding type stirred friction deposition additive manufacturing device, such as... Figure 1-8 As shown, the additive manufacturing apparatus based on powder feeding type stir friction deposition according to an exemplary embodiment of the present invention includes, from top to bottom, an extrusion device 1, a rotary-thrust coupling 2, a drive shaft 3, an extrusion rod 8, a connecting shaft 4, a powder feeding sleeve 5, a cutter handle 6, and a stirring head 7.

[0059] Combination Figure 1 As shown, the extrusion device 1 is used to provide the extrusion pressure required for powder compaction and extrusion processes. The extrusion device 1 is fixed on the frame and does not rotate during processing.

[0060] As an alternative example, the extrusion device may employ an electric push rod, a hydraulic push rod, or a pneumatic push rod.

[0061] like Figures 1-2 As shown, the rotary-thrust coupling 2 serves to transmit thrust to the rotating drive shaft 3. In actual design, various mechanical structures can be adopted.

[0062] As an optional example, the rotary-thrust coupling 2 can consist of an upper coupling 21 and a lower coupling 22, which are connected by a first screw hole 212 and a second screw hole 222. The upper coupling 21 is connected to the extrusion device 1 via a first thread 211. The thrust is transmitted to the drive shaft 3 via a pair of tapered roller bearings 223, which are locked to the tapered roller bearings 223 by double nuts 221. The first sealing ring 224 prevents bearing lubricating oil from leaking out.

[0063] Combination Figure 1 , 3 ~5. The tool holder 6 is connected to the spindle of the machine tool, and the function of the tool holder 6 is to transmit the torque of the machine tool spindle to the stirring head 7 and the connecting shaft 4 through the conical surface 61, so that they rotate at the same speed. At the same time, the conical surface 61 helps to improve the centering of the overall structure.

[0064] As an optional example, the handle 6 can be connected to the spindle via the third screw hole 62, the stirring head 7 can be connected to the handle via the third thread 64, and the connecting shaft 4 can be connected to the handle via the second thread 63.

[0065] Combination Figures 1-2 4-5, 8. The function of the drive shaft 3 is to transmit thrust, perform axial movement, and maintain the same speed rotation as the connecting shaft 4, the knife handle 6, and the stirring head 7. The upper end of the drive shaft 3 is provided with a locking thread 31, below which is the bearing mating surface 32, and the lower end is provided with an internal thread 34.

[0066] An extrusion rod 8 is provided below the drive shaft 3. The extrusion rod 8 is used to compact and extrude the powder in the extrusion channel.

[0067] As an optional example, the drive shaft 3 can transmit torque and rotate with the internal spline 41 on the upper part of the connecting shaft 4 via its external spline 33. The lower end of the connecting shaft 4 is provided with an external thread 43.

[0068] Combination Figure 1 5-6, The function of the powder feeding sleeve 5 is to provide a channel for powder conveying. The powder feeding sleeve 5 does not rotate during operation.

[0069] As an alternative example, the powder is fed into the channel 51 by gas or screw, then the powder fills the space formed by the second sealing ring 52, and finally is fed into the extrusion channel through the powder feeding hole 42 on the connecting shaft 4.

[0070] Combination Figure 1 , 7The function of the stirring head 7 is to stir and deform the compacted powder and the additive layer by friction, thereby realizing the powder forming and metallurgical bonding between the additive layers. The upper end of the stirring head has a connecting thread 71, the lower end of the connecting thread is the end face 72, and the lower end is the shoulder 73. The shoulder of the stirring head is composed of a central hole 732 and a friction zone 733.

[0071] As an optional example, the friction zone 733 can be designed into a certain shape, such as a vortex or a key, to promote plastic flow during the deformation process.

[0072] This invention also discloses a powder-feeding stirred triboelectric deposition additive manufacturing method, which mainly includes the following steps:

[0073] (1) Start-up: Start the machine tool spindle and set the rotation speed to Vrpm. The machine tool spindle is connected to the tool holder 6 and drives the tool holder to rotate. The stirring head 7 starts to rotate under the drive of the tool holder 6. Move the XYZ axis of the machine tool to make the stirring head 7 contact the substrate and provide a certain forging force. The substrate starts to generate heat through friction under the action of the shoulder 73.

[0074] (2) Powder feeding: The powder is fed to the hollow channel of the stirring head 7 through the powder feeding sleeve 5. At this time, the powder is still in a loose state and the powder feeding amount is QmL.

[0075] (3) Compaction: At this time, the required extrusion pressure is small. The powder is quickly compacted under the action of the extrusion rod. The extrusion pressure is provided by the extrusion device. The compaction process is controlled according to the motor torque or gas (liquid) pressure feedback, and the pressure data P1kN is obtained.

[0076] (4) Extrusion and stirring friction: Control the extrusion rod pressing speed to v1 mm / min and obtain its pressure data P2 kN (before starting the actual additive manufacturing, the density of the powder under different pressures should be tested to obtain the functional relationship of density with pressure. When the pressure is P2, the density of the powder block is k). Control the machine tool moving speed to v2 mm / min. In order to make the processing stable, the extrusion rod pressing speed v1 should match the machine tool moving speed v2 and satisfy the following formula (1):

[0077]

[0078] In the formula, The diameter of the hollow channel in stirring head 7 is in mm. d represents the shoulder diameter of the stirring head in mm, and d represents the thickness of the additive layer per pass in mm.

[0079] At the same time, a temperature sensor and an infrared temperature probe are set at the substrate position, and the rotation speed and moving speed of the stirring head are automatically adjusted according to the temperature feedback; when the measured pressure data or the required moving speed changes, the pressing speed of the extrusion rod is automatically controlled by feedback according to formula (1).

[0080] (5) Extrusion rod retraction: The extrusion rod retracts to the initial position.

[0081] The above-described embodiments are merely some implementation methods of this application. For those skilled in the art, various modifications and improvements can be made without departing from the inventive concept of this application, and these all fall within the protection scope of this application.

Claims

1. A powder-fed additive manufacturing apparatus based on friction stir processing, characterized in that, It comprises, from top to bottom, an extrusion device (1), a rotary-thrust coupling (2), a transmission shaft (3), an extrusion rod (8), a coupling shaft (4), a powder feeding sleeve (5), a tool holder (6) and a stirring head (7): The extrusion device (1) is used to provide the extrusion force required in the powder compaction and extrusion process; The rotary-thrust coupling (2) is used to transmit thrust to the rotating transmission shaft (3); The transmission shaft (3) performs axial movement and transmits thrust; The coupling shaft (4) is used to transmit torque to the transmission shaft (3); The powder feeding sleeve (5) is used to provide a channel for powder delivery; The tool holder (6) is used to transmit the torque of the main shaft to the stirring head (7) and the coupling shaft (4) through the conical surface (61), respectively, so that the stirring head (7) and the coupling shaft (4) rotate at the same speed, and the conical surface (61) improves the centering of the overall structure; The stirring head (7) is used to stir and frictionally deform the compacted powder and the additive layer; The extrusion rod (8) extrudes and compacts the powder during the additive process and is finally extruded into the stir-friction area.

2. The powder-fed friction stir deposition-based additive manufacturing device of claim 1, wherein, The extrusion device (1) is fixed on the machine frame and does not rotate during the additive manufacturing process.

3. The powder-fed friction stir deposition-based additive manufacturing device of claim 2, wherein, The extrusion device is an electric push rod, a hydraulic push rod or a pneumatic push rod.

4. The powder-fed friction stir deposition-based additive manufacturing device of claim 1, wherein, The transmission shaft (3), the extrusion rod (8), the coupling shaft (4), the tool holder (6) and the stirring head (7) are always in the same speed rotation state during the additive manufacturing process.

5. The powder-fed friction stir deposition-based additive manufacturing device of claim 4, wherein, The coupling shaft (4) transmits torque to the transmission shaft (3) through spline or flat key cooperation, thereby realizing the same speed rotation.

6. The powder-fed friction stir deposition-based additive manufacturing device of claim 1, wherein, The friction zone (733) of the stirring head (7) has a certain geometric shape.

7. The powder-fed friction stir deposition-based additive manufacturing device of claim 6, wherein, The certain geometric shape of the friction zone is a spiral, a tooth shape or a groove shape.

8. A method of additive manufacturing by means of powder-fed friction stir deposition using the device according to any one of claims 1 to 7, characterized in that It consists of five steps: starting, powder feeding, compaction, extrusion and stir-friction, and extrusion rod retraction, specifically including: (1) Start: Start the main shaft, rotate the stirring head, and move the machine tool XYZ axis to make the stirring head contact with the substrate; (2) Powder feeding: deliver the powder to the hollow channel of the stirring head through the powder feeding device; (3) Compaction: the powder is quickly cold-pressed under the action of the extrusion rod; (4) Extrusion and stir-friction: the powder is extruded by the extrusion rod and shaped and metallurgically bonded between the additive layers through stir-friction; (5) Extrusion rod retraction: the extrusion rod retracts to the initial position.

9. The additive manufacturing method of claim 8, wherein, The substrate is preheated by the contact between the stirring head (7) and the substrate to meet the powder forming requirements, while providing a closed space for powder extrusion.

10. The additive manufacturing method of claim 8, wherein, During the compaction process, the extrusion rod is quickly pressed down, and its compaction process is controlled according to the motor torque or gas pressure or liquid pressure feedback.

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