A friction stir additive manufacturing method and apparatus with mechanical interlocking structure

Abstract

The application discloses a friction stir additive manufacturing method and device with a mechanical interlocking structure. As a stirring head moves horizontally or longitudinally at a set speed, a first layer and a first pass of an additive area are formed. According to requirements, other passes of the first layer are formed in parallel with the first layer and the first pass. When a second layer of the additive is formed, the stirring head moves longitudinally or horizontally, so that the first layer of the deposited layer and the second layer of the deposited layer form a grid shape. At the same time, the second layer of the thermoplastics fills the gap in the first layer of the deposited layer, and a mechanical interlocking structure is formed in the organization. The forming steps of the first layer and the second layer are repeated until the required additive height is reached. The friction stir additive manufacturing device and method with the mechanical interlocking structure can realize high-quality additive manufacturing of various materials, increase the density and toughness of the materials, improve the utilization rate and quality of the materials, and solve the problem of low material utilization rate in the friction stir additive manufacturing.

Description

Technical Field

[0001] This invention relates to the field of additive manufacturing technology, and specifically to an additive manufacturing method and apparatus with a mechanically interlocked stirring friction structure. Background Technology

[0002] Additive manufacturing (AM) is a process that uses computer technology to pre-create and plan 3D models, and then uses a digital, controllable heat source to melt, clad, or stack materials layer by layer to rapidly form structural or functional parts. It has five major technical characteristics: digital manufacturing, dimensional reduction manufacturing, stacking manufacturing, direct manufacturing, and rapid manufacturing. It has attracted widespread attention worldwide and has brought about a series of profound changes to traditional manufacturing industries. It can be widely used in aerospace, defense, medical, architectural design, automobile manufacturing and other fields.

[0003] Friction stir deposition (AFSD) is a solid-state metal forming technology based on the principle of filler-type friction stir welding. Existing AFSD methods primarily involve the welding and stacking of multiple layers of materials. The additive process is similar to multi-layer lap joints in friction stir welding, a spatial lap process that includes lateral additive processing perpendicular to the lap direction and additive processing parallel to the material thickness direction. The microstructure and properties of the lap joints in AFSD are closely related to the interface state, and are prone to interface distortion, coarse microstructure, and cold lap defects, which reduce the material's properties. Achieving fully automated digital processing in AFSD is a major challenge. Another issue that needs to be addressed is how to improve material utilization. Existing AFSD methods cannot achieve high material utilization; after additive processing, the AFSD blank still requires post-processing to remove excess substrate. The more that is removed, the lower the material utilization rate.

[0004] Therefore, existing technologies have shortcomings and need to be improved. Summary of the Invention

[0005] The purpose of this invention is to propose a friction stir additive manufacturing method and apparatus with a mechanical interlocking structure based on the technical principle of friction stir additive manufacturing. This avoids the phenomenon of redundant curling around the metal rod caused by the lack of constraint of the plasticized material in the radial and axial directions. At the same time, it can eliminate interface non-bonding defects and solve the problems of large processing allowance and low material utilization in friction stir additive manufacturing.

[0006] The present invention adopts the following technical solution:

[0007] A friction stir additive manufacturing method with a mechanically interlocked structure includes the following steps: First, the substrate to be added is placed on a substrate and clamped and fixed. A high-speed rotating stirring needle penetrates the interface between the substrate and the substrate and inserts into the substrate to a certain depth. As the stirring head moves laterally or longitudinally at a set travel speed, a first layer and a first pass additive zone are formed. Other first pass additive zones are formed parallel to the first layer and the first pass additive zone as needed. When performing the second layer additive manufacturing, the stirring head moves longitudinally or laterally, so that the first and second deposited layers form a mesh. At the same time, the second layer of thermoplasticized material fills the gaps in the first deposited layer, forming a mechanically interlocked structure. The forming steps of the first and second layers are repeated until the required additive height is reached.

[0008] In the friction stir additive manufacturing method described above, during the formation of each additive zone, the spindle drives the limiting device to move along the additive direction, and the limiting plate must fix the shape of the material before it cools down.

[0009] The friction stir additive manufacturing method described herein involves multiple additive manufacturing processes based on the required width of the additive part, with the gap between two adjacent additive manufacturing zones controlled between 2-4 mm.

[0010] In the aforementioned friction stir additive manufacturing method, the depth of the additive zone is controlled to be 4-6 mm.

[0011] In the aforementioned friction stir additive manufacturing method, the distance between the limiting plate and the stirring head in the limiting device is controlled at 500mm-550mm, the plate width is controlled at 10mm-15mm, and the plate thickness is controlled at 1mm-1.5mm.

[0012] In the aforementioned friction stir additive manufacturing method, the gap between two adjacent additive zones in the second layer is also controlled between 2-4 mm.

[0013] In the aforementioned friction stir additive manufacturing method, the subsequent additive direction can be arbitrarily changed according to the spindle additive angle.

[0014] The aforementioned friction stir additive manufacturing method can achieve alternating processing in the transverse, longitudinal, and gridded additive directions.

[0015] The friction stir additive manufacturing apparatus according to any of the methods includes a main shaft 1, a stirring head 2, and a limiting device 3; the limiting device 3 is fixed to the main shaft 1, and the main shaft 1 drives it to move; wherein, the limiting device 3 includes a fixing frame 301 and a replaceable limiting plate 302, the fixing frame 301 and the replaceable limiting plate 302 are connected by threads, and the limiting plate can control the shape of the side of the additive zone; the replaceable limiting plate can be replaced according to the desired side shape.

[0016] In the aforementioned friction stir additive manufacturing apparatus, the limiting plate 302 can form trapezoidal or wavy sides; the distance between the limiting plate 302 and the stirring head 2 is controlled at 500mm-550mm, the plate width is controlled at 10mm-15mm, and the plate thickness is controlled at 1mm-1.5mm, so as to obtain an ideal additive manufacturing zone morphology.

[0017] The technical effects of this invention are as follows:

[0018] (1) The stir friction additive manufacturing apparatus and method with mechanical interlock structure provided by the present invention can realize high-quality additive manufacturing of a variety of materials, while increasing the density and toughness of the materials, improving the material utilization rate and quality, and solving the problem of low material utilization rate in stir friction additive manufacturing.

[0019] (2) This invention can meet the needs of large-size friction stir additive manufacturing of large components, and can also be promoted and applied in metal structures with high requirements for material structure and mechanical properties in the fields of launch vehicles, ships, automobiles, etc., to realize efficient, high-quality and low-cost manufacturing of complex metal structures. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the friction stir additive manufacturing apparatus with a mechanical interlocking structure according to the present invention;

[0021] Figure 2 This is a schematic diagram of the main view of the limiting device;

[0022] Figure 3 This is a schematic diagram of the left side view of the limiting device;

[0023] Figure 4 These are cross-sectional views of various morphological gradients of the sedimentary layer; a) the side is an inward-curving arc shape, b) the cross-section is an inverted trapezoid, and c) the cross-section is a trapezoid.

[0024] Figure 5 It is a cross-sectional view of the trapezoidal gradient of the sedimentary layer.

[0025] In the diagram: 1 is the main shaft, 2 is the stirring head, 3 is the shaping device, 301 is the fixing frame, and 302 is the replaceable shaping plate. Detailed Implementation

[0026] The present invention will be described in detail below with reference to specific embodiments.

[0027] like Figure 1 As shown, this invention provides a friction stir additive manufacturing apparatus with a mechanically interlocked structure, including a main shaft 1, a stirring head 2, and a shaping device 3. The shaping device 3 is fixed to the main shaft 1, and the main shaft 1 drives its movement. The shaping device 3 includes a fixing frame 301 and a replaceable shaping plate 302, as shown... Figure 2 , 3As shown, the fixed frame 301 and the replaceable limiting plate 302 are connected by threads, and the limiting plate can control the shape of the side of the additive manufacturing zone. The mixing head 2 has through holes machined inside for conveying the bar stock.

[0028] Preferably, the limiting plate 302 in the limiting device 3 can be replaced according to the side morphology requirements, such as... Figure 4 As shown, the distance between the limiting plate 302 and the stirring head 2 is controlled at 500mm-550mm, the plate width is controlled at 10mm-15mm, and the plate thickness is controlled at 1mm-1.5mm to obtain the ideal additive manufacturing zone morphology.

[0029] A friction stir additive manufacturing method with a mechanically interlocked structure includes the following steps:

[0030] Step 1: First, place the additive manufacturing board to be used on the substrate and clamp it in place.

[0031] Step two: The high-speed rotating stirring head penetrates the interface between the additive board and the substrate and inserts into the substrate to a certain depth. As the stirring head moves laterally at a set travel speed, the first layer and first additive zone are formed. At the same time, the spindle drives the trapezoidal shaping device to move along the additive direction. The trapezoidal shaping plate must fix its shape before the material cools.

[0032] Step 3: Perform multiple additive manufacturing passes according to the required width of the additive part, with the gap between adjacent additive manufacturing passes controlled between 2-4 mm. If the gap is too large, the second thermoplasticized deposition layer will not be fully filled, failing to form a mechanically interlocking structure, and defects will form due to unbonded interfaces and migration interfaces; if the gap is too small, the filling speed will be slow, and the unbonded interfaces will gradually become migration interfaces.

[0033] Step four: During the second layer of additive manufacturing, the stirring head moves longitudinally, creating a mesh-like overlap between the first and second deposition layers; simultaneously, the thermoplasticized second deposition layer fills the gaps in the first deposition layer, forming a mechanically interlocked structure; the gap between adjacent additive zones in the second layer is also controlled between 2-4 mm. Figure 5 This is a gradient cross-section diagram of the trapezoidal sedimentary layer.

[0034] Step 5: The third deposition layer forms a grid-like overlap and mechanical interlocking structure with the second deposition layer to achieve multi-layer material stacking until the required additive height is reached.

[0035] Example

[0036] This embodiment relates to a method for friction stir additive manufacturing with a mechanical interlocking structure, the steps of which are as follows:

[0037] Step 1: First, place the additive manufacturing board to be used on the substrate and clamp it in place.

[0038] Step two: The high-speed rotating stirring head penetrates the interface between the additive board and the substrate and inserts into the substrate to a certain depth. The stirring head rotates at 2000 rpm. As the stirring head moves laterally at a travel speed of 500 mm / min, the first layer and first pass of additive manufacturing are formed. At the same time, the spindle drives the trapezoidal limiting device to move along the additive manufacturing direction. The distance between the limiting plate and the stirring head in the limiting device is 525 mm, the plate width is 13 mm, the plate thickness is 1.2 mm, and the inclination angle with the horizontal direction is 78°. The trapezoidal limiting plate fixes its shape before the material cools.

[0039] Step 3: The additive width is 7mm, and the gap between two adjacent additive zones is 2.5mm, forming seven additive zones.

[0040] Step four: During the second layer of additive manufacturing, the stirring head moves longitudinally, creating a mesh-like overlap between the first and second deposition layers; simultaneously, the thermoplasticized second deposition layer fills the gaps in the first deposition layer, forming a mechanically interlocked structure; the gap between adjacent additive zones in the second layer is also 2.5mm. Figure 5 This is a gradient cross-section diagram of the trapezoidal sedimentary layer.

[0041] Step 5: The third deposition layer forms a grid-like overlap and mechanical interlocking structure with the second deposition layer. Repeat this step until the additive height of 20 layers is reached.

[0042] It should be understood that those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims.

Claims

1. A method for friction stir additive manufacturing with a mechanical interlocking structure, characterized in that, The process includes the following steps: First, the additive board to be added is placed on the substrate and clamped and fixed. A high-speed rotating stirring needle penetrates the overlap interface between the additive board and the substrate and inserts into the substrate to a certain depth. As the stirring head moves laterally or longitudinally at a set travel speed, the first layer and the first pass of additive manufacturing are formed. Other additive layers of the first layer are formed parallel to the first pass of additive manufacturing as needed. When performing the second layer of additive manufacturing, the stirring head moves longitudinally or laterally, so that the first and second deposited layers form a grid-like overlap. At the same time, the second layer of thermoplasticized material fills the gaps in the first deposited layer, forming a mechanically interlocking structure. The forming steps of the first and second layers are repeated until the required additive height is reached. Multiple additive manufacturing passes are performed according to the required width of the additive part, and the gap between two adjacent additive layers is controlled between 2-4 mm. The gap between two adjacent additive layers in the second layer is also controlled between 2-4 mm.

2. The friction stir additive manufacturing method according to claim 1, characterized in that, During the forming of each additive zone, the spindle drives the limiting device to move along the additive direction, and the limiting plate must fix the shape of the material before it cools down.

3. The friction stir additive manufacturing method according to claim 1, characterized in that, The depth of the additive manufacturing zone is controlled at 4-6mm.

4. The friction stir additive manufacturing method according to claim 1, characterized in that, The distance between the limiting plate and the stirring head in the limiting device is controlled at 500mm-550mm, the plate width is controlled at 10mm-15mm, and the plate thickness is controlled at 1mm-1.5mm.

5. The friction stir additive manufacturing method according to claim 1, characterized in that, The spindle additive direction can be adjusted arbitrarily according to the needs of subsequent additive manufacturing.

6. The friction stir additive manufacturing method according to claim 1, characterized in that, It can achieve alternating horizontal and vertical additive manufacturing directions and gridded additive manufacturing directions.

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