Friction stir deposition additive device and method for enhancing interface bonding of wide plate

Abstract

This invention discloses a friction stir deposition additive manufacturing apparatus and method for enhancing interfacial bonding of wide sheet metal, comprising a stirring head, a push rod, a raw material rod, a sleeve, and a clamping ring. The stirring head has a hollow structure, with an axially movable push rod fixed inside the hollow cavity. The cross-sectional dimensions of the raw material rod are the same as those of the push rod. During additive manufacturing, the raw material rod is inserted from the bottom of the stirring head and tightly bonded to the hollow cavity. Through the self-rotation and reverse axial movement of the stirring head and sleeve, the material on the upper layer of the sheet metal, which has been plasticized by friction stir, is squeezed into the gap formed by the two. When the stirring head and sleeve rapidly move back to their initial positions, the plasticized material is pressed back, resulting in protruding "small pieces" at the interface between the upper and lower sheet metal layers. These small pieces are arranged at the interface of horizontally adjacent deposition passes of the sheet metal, thus forming an overlap and self-locking at the interface, thereby enhancing the interfacial bonding.

Description

Technical Field

[0001] This invention belongs to the field of additive manufacturing technology for metal materials, specifically relating to a stir friction deposition additive manufacturing apparatus and method for enhancing the interfacial bonding of wide sheet metal. Background Technology

[0002] Additive friction stir deposition (AFSD) technology primarily utilizes the frictional heat generated between the tool head and the workpiece material, along with the stirring action of the tool head, to induce plastic deformation in the material. This thermoplasticizes the metal material to be added, and under the stirring and upsetting action of the tool head, it bonds with a substrate or existing additive layer. Ultimately, the thermoplasticized material is accumulated layer by layer to form a structural component. AFSD is an emerging solid-state additive technology where the material does not melt during the process, thus eliminating melting defects such as pores and hot cracks. It also boasts high additive efficiency, making it suitable for additive manufacturing of large-sized parts. Furthermore, the additive process has low environmental requirements, theoretically allowing it to be performed in a vacuum or underwater.

[0003] The additive manufacturing process is a spatial overlapping process, including transverse additive manufacturing perpendicular to the overlap direction and longitudinal additive manufacturing parallel to the material thickness direction. Currently, the application of AFSD technology is mainly limited by the interfacial bonding strength. Most of the reported components are cylindrical, frame-shaped, and stiffened structures obtained by longitudinal additive manufacturing of a single deposition layer. There are few reports of applications for preparing plate-shaped components mainly by transverse additive manufacturing perpendicular to the overlap direction. The main reason is that the contact interface between the deposition layers of transverse additive manufacturing is only the side of the deposition layer. Compared with longitudinal additive manufacturing, its interlayer contact area is small, its viscoplasticity is poor, and the interfacial bonding is weak.

[0004] Currently, the interfacial bonding strength of additive components prepared using AFSD technology can only reach about 80% of that of the parent material. Reported improvements to enhance interfacial bonding mainly include designing the stirring head structure to increase the interlayer contact area (e.g., CN117381135 A, CN 114986092 A, CN 116160108 A) and auxiliary heating (CN 113351984 B, CN117047256 A). However, for wide-width sheet components primarily manufactured using transverse additive processing, the improvement effects of these methods are very limited. Summary of the Invention

[0005] The purpose of this invention is to provide a friction stir deposition additive manufacturing apparatus and method for enhancing the interfacial bonding of wide sheet metal. Through the self-rotation and counter-axial movement of the stirring head and sleeve, the material on the upper layer of the sheet metal, plasticized by friction stir, is compressed and fills the gaps formed between them. When the stirring head and sleeve rapidly move back to their initial positions, the plasticized material is pressed back, resulting in protruding "small pieces" at the interface between the upper and lower sheet metal layers. These small pieces are arranged at the interfacial bonding points of horizontally adjacent deposition passes, thus forming overlap and self-locking at the interface of the sheet metal, thereby enhancing the interfacial bonding.

[0006] To achieve the above-mentioned objectives, the technical solution of this invention is as follows:

[0007] A friction stir deposition additive manufacturing apparatus for enhancing interfacial bonding of wide sheet metal includes a stirring head, a push rod, a raw material rod, a sleeve, and a clamping ring. The stirring head has a hollow structure, and an axially movable push rod is fixed inside the hollow cavity. The cross-sectional dimensions of the raw material rod are the same as those of the push rod. During additive manufacturing, the raw material rod is inserted from the bottom of the stirring head and tightly bonded to the hollow cavity of the stirring head. The sleeve surrounds the outside of the stirring head and is coaxially and concentrically integrated with the stirring head. The sleeve and the stirring head can slide relative to each other vertically or rotate independently.

[0008] Preferably, both the push rod and the stirring head are made of relatively hard tool steel;

[0009] Preferably, the sleeve is made of hard tool steel and has threads tapped on the bottom outer surface;

[0010] The clamping ring is fixed to the outside of the sleeve and serves to clamp and protect it.

[0011] The aforementioned agitation-friction deposition repair device can be mounted on external equipment such as CNC machine tools and parallel robotic arms for operation.

[0012] A method for enhancing interfacial bonding of wide sheet metal through friction stir deposition additive manufacturing, using the aforementioned apparatus, specifically includes the following steps:

[0013] Step 1: Fix the substrate in the processing cylinder with a clamp, add raw material rods into the stirring head; lift the sleeve and clamping ring, lower the stirring head, and move it to the substrate deposition area.

[0014] Step 2: Start the friction stir deposition additive manufacturing system, so that the stirring head rotates at high speed on the substrate surface, while the push rod pushes the raw material rod downward. When the raw material reaches the shoulder end face of the stirring head, move the stirring head to obtain a primary deposition layer of a certain thickness.

[0015] Step 3: After the first additive manufacturing is completed, move the stirring head horizontally and repeat Step 2 to complete the second additive manufacturing, so that the side edges of the first and second deposition layers are tightly bonded. Repeat this process multiple times to perform multiple deposition passes, and a single-layer wide sheet material can be prepared on the substrate.

[0016] Step 4: Using the single-layer wide sheet material prepared in Step 3 as a new substrate, repeat Steps 2 and 3 to complete the preparation of the double-layer wide sheet material.

[0017] Step 5: Remove the raw material rod from the mixing head, lower the push rod so that the lower surface of the push rod is flush with the shoulder end face of the mixing head; then lower the sleeve and clamping ring, and gently place them together with the mixing head on the upper surface of the prepared double-layer additive board, so that the axis of the mixing head is evenly divided by the contact interface of the two adjacent additive passes. Set this position as the initial position of the sleeve and the mixing head.

[0018] Step Six: Simultaneously rotate the sleeve and stirring head to generate friction between their tips and the upper surface of the sheet material. While rotating, the sleeve descends at a constant speed, inserting into the upper layer of the sheet material, while the stirring head rises at a constant speed, leaving the upper surface. This causes the material in the upper layer of the sheet material to undergo plastic deformation again under the stirring friction of the sleeve. After the sleeve and stirring head have descended and risen to certain heights respectively, stop their opposing axial movements and allow them to rotate in place. Through sufficient stirring friction, the gap between the sleeve and stirring head is now completely filled with the thermoplasticized material. Once the plasticized material has completely filled the gap, stop the rotation and quickly move the sleeve and stirring head back to their initial positions. At this point, the plasticized material in the original gap is quickly pressed back, creating protruding "small lumps" at the interface between the upper and lower layers of sheet material.

[0019] Step 7: The sleeve and stirring head remain on the upper surface of the sheet for a certain period of time. After the material has solidified, they are lifted together with the clamping ring. The resulting protruding "small pieces" can form an overlap and self-locking at the joint interface of the sheet, thereby strengthening a part of the joint interface of the sheet.

[0020] Step 8: Repeat steps 5 to 7 to form multiple overlaps at the joints of each adjacent pass on the upper layer of the sheet metal.

[0021] Step 9: Repeat steps 1 to 8 above to complete the preparation of the three-layer wide sheet material with enhanced interface bonding. By doing so, wide sheets of the required height can be prepared.

[0022] In step one, the raw material rods can always be made of the same material, or different materials can be used midway through the process. This method can be used to prepare single-layer wide metal plates, as well as heterogeneous wide metal plates composed of different materials.

[0023] Preferably, the raw material rod can be an aluminum alloy, magnesium alloy, titanium alloy, or the above alloys with composite reinforcing phases.

[0024] Furthermore, in steps three and four, it is necessary to ensure that the previous deposition layer has been fully cooled and solidified before each additive manufacturing process.

[0025] Preferably, the outer surface of the additive board material needs to be cleaned before proceeding to step five.

[0026] Preferably, in step six, the height of the sleeve descent and the height of the stirring head elevation should both be less than 25% of the height of the single-layer deposition layer, and after the opposing axial movements of the two stop, the time for in-situ self-rotation is only 0 to 5 seconds.

[0027] The beneficial effects of this invention are as follows:

[0028] 1. Currently, the coaxial feeding method for bar stock is the most developed technology category in AFSD technology, and the equipment has been launched on the market. This invention can achieve the preparation of wide sheet metal components with enhanced interface bonding simply by modifying the tool head in the equipment. The technical means are simple, easy to implement, safe and reliable.

[0029] 2. The present invention uses the stirring friction of the hydraulic rod and the sleeve to form an overlap and self-locking at the connection interface, thereby improving the interface bonding strength. This solid-phase connection method will not destroy the original structure of the AFSD component, and can even realize the secondary dynamic recrystallization of the interface structure, thereby refining the grains.

[0030] 3. This invention can generate protruding "small blocks" at the interface between two layers of sheet metal. These small blocks are arranged at the interface of adjacent horizontal deposition passes of the sheet metal, which can enhance the interface bonding in the transverse additive direction of the component as well as the interface bonding in the longitudinal additive direction. It can realize the preparation of wide sheet metal and is also applicable to the connection of dissimilar metals, thus broadening the application scope of AFSD technology. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the stir-friction deposition additive manufacturing apparatus provided by the present invention, in which the additive manufacturing step is underway;

[0032] Figures 2(a), 2(b), 2(c), and 2(d) are exploded schematic diagrams of the interface bonding enhancement step performed by the stir-friction deposition additive manufacturing apparatus provided by the present invention.

[0033] Figure 3 This is a schematic diagram of the interface bonding reinforcement area of ​​a wide sheet material prepared using the method provided in this invention. Detailed Implementation

[0034] The present invention will be described in detail below with reference to specific embodiments. Example

[0035] like Figure 1As shown, this embodiment provides a stir friction deposition additive manufacturing apparatus for enhancing interfacial bonding. The apparatus includes: a substrate 1, a deposition layer 2, a push rod 3, a raw material rod 4, a stirring head 5, a sleeve 6, and a clamping ring 7.

[0036] The stirring head 5 has a hollow structure, with the hollow cavity being a cuboid with sides of 20mm*20mm*200mm. An axially movable push rod 3 is fixed inside the cavity. Both the push rod 3 and the stirring head 5 are made of tool steel, with the push rod measuring 19.8mm*19.8mm*100mm. The raw material rods 4 are all made of AA6061-T6 aluminum alloy, with the same dimensions as the push rod. During additive manufacturing, the raw material rods are inserted from the bottom of the stirring head, ensuring that both the raw material rods 4 and the push rod 3 can fit tightly into the inner cavity of the stirring head 5 while allowing for smooth up-and-down movement.

[0037] The sleeve 6 surrounds the outside of the stirring head 5, has a wall thickness of 3.5mm, and is coaxially and concentrically integrated with the stirring head 5. It can slide relative to the stirring head 5 vertically or rotate independently. The sleeve 6 is made of tool steel, and its bottom outer surface is tapped with threads of 50mm in height. The clamping ring 7 is fixed to the outside of the sleeve 6, serving a clamping and protective function.

[0038] The aforementioned stir-friction deposition additive manufacturing device for enhancing the interfacial bonding of wide sheet metal can be mounted on external equipment such as CNC machine tools and parallel robotic arms for driving. The driving mechanisms of the various components of this device are not shown in the figure.

[0039] like Figure 1 As shown in Figure 2, a stir-friction deposition additive manufacturing method for enhancing interfacial bonding of wide sheet metal, using the aforementioned apparatus, specifically includes the following steps:

[0040] Step 1: Fix the substrate 1 in the processing cylinder with a clamp, add the raw material rod 4 into the stirring head 5; lift the sleeve 5 and clamping ring 7, lower the stirring head 5, and move it to the deposition area of ​​the substrate 1.

[0041] Step 2: Start the friction stir deposition additive manufacturing system, so that the stirring head 5 rotates at high speed on the surface of the substrate 1. At the same time, the push rod 3 pushes the raw material rod 4 downward. When the raw material reaches the shoulder end face of the stirring head 5, move the stirring head 5 to obtain a primary deposition layer with a thickness of 4.5 mm and a width of 32-36 mm. The feeding speed is 0.8 mm / s, the rotation speed of the stirring head 5 is 360 r / min, and the planar movement speed is 120 mm / min.

[0042] Step 3: After the first additive manufacturing is completed, move the stirring head horizontally in parallel and repeat Step 2 to complete the second additive manufacturing, so that the side edges of the first and second deposition layers are tightly bonded. Repeat this process multiple times, for a total of 7 deposition passes, and the total width of the prepared single-layer sheet is 242 mm.

[0043] Step 4: Using the single-layer board material prepared in Step 3 as a new substrate, repeat Steps 2 and 3 to complete the preparation of the double-layer wide board material.

[0044] Step 5: Clean the additively produced sheet material, remove the raw material rod 4 from the mixing head 5, and lower the push rod 3 so that the lower surface of the push rod 3 is flush with the shoulder end face of the mixing head 5. Then lower the sleeve 6 and clamping ring 7, and gently place them together with the mixing head 5 onto the cleaned double-layer additively produced sheet material, as shown in Figure 2(a), so that the axis of the mixing head is evenly divided by the contact interface of two adjacent additive passes. This position is set as the initial position of the sleeve 6 and the mixing head 5.

[0045] Step Six: Simultaneously rotate the sleeve 6 and the stirring head 5 at a rotation speed of 280 r / min, causing the front ends of the sleeve 6 and the stirring head 5 to rub against the upper surface of the sheet. While rotating, the sleeve 6 descends 1 mm at a speed of 0.2 mm / s, inserting into the upper layer of the sheet, while the stirring head 5 rises 1 mm at a speed of 0.2 mm / s, leaving the upper surface of the sheet, as shown in Figure 2(b). This causes the material in the upper layer of the sheet to undergo plastic deformation again under the stirring friction of the sleeve 6. After the sleeve 6 and the stirring head 5 reach the set position, stop their opposite axial movement and only rotate in place. After sufficient stirring friction, the gap between the sleeve 6 and the stirring head 5 is completely filled with thermoplasticized material. Stop the rotation after 3 seconds and quickly move the sleeve 6 and the stirring head 5 back to the initial position, as shown in Figure 2(c). At this time, the plasticized material in the original gap is quickly pressed back, which creates a protruding "small block" at the interface between the upper and lower layers of the sheet.

[0046] Step 7: The sleeve 6 and stirring head 5 remain on the upper surface of the sheet for 5 seconds to allow the material to solidify. Then, they are lifted together with the clamping ring 7, as shown in Figure 2(d). The resulting protruding "small pieces" can form overlaps and self-locking at the joint interface of the sheet, thus strengthening one part of the joint interface. Step 8: Repeating steps 5 to 7 will create multiple overlaps at the joint of each adjacent pass on the upper layer of the sheet, such as... Figure 3 As shown.

[0047] Ultimately, the wide plate with enhanced interface bonding prepared in this embodiment is made of AA6061-T6 aluminum alloy with a height of 9mm and a width of 242mm.

[0048] 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 enhancing interfacial bonding of wide sheet metal through friction stir deposition additive manufacturing, characterized in that, A friction stir deposition additive manufacturing apparatus for enhancing the interfacial bonding of wide sheet metal is disclosed. The apparatus includes a stirring head, a push rod, a raw material rod, a sleeve, and a clamping ring. The stirring head has a hollow structure, with an axially movable push rod fixed within the hollow cavity. The raw material rod has the same cross-sectional dimensions as the push rod and is inserted into the bottom of the stirring head during additive manufacturing, tightly fitting into the hollow cavity. The sleeve surrounds the outside of the stirring head and is coaxially and concentrically integrated with it. The sleeve and the stirring head can slide relative to each other vertically and can also rotate independently. The friction stir deposition additive manufacturing method includes the following steps: Step 1: Fix the substrate in the processing cylinder with a clamp, add raw material rods into the stirring head; lift the sleeve and clamping ring, lower the stirring head, and move it to the substrate deposition area; Step 2: Start the friction stir deposition additive manufacturing system, make the stirring head rotate at high speed on the substrate surface, and at the same time push the raw material rod downward with the push rod. When the raw material reaches the end face of the stirring head, move the stirring head to obtain a primary deposition layer of a certain thickness. Step 3: After the first additive manufacturing is completed, move the stirring head horizontally and repeat Step 2 to complete the second additive manufacturing, so that the side edges of the first and second deposition layers are tightly bonded. Repeat this process multiple times to perform multi-pass deposition, that is, to complete the preparation of a single-layer wide plate on the substrate. Step 4: Using the single-layer wide sheet material prepared in Step 3 as a new substrate, repeat Steps 2 and 3 to complete the preparation of the double-layer wide sheet material. Step 5: Remove the raw material rod from the mixing head, lower the push rod so that the lower surface of the push rod is flush with the end face of the mixing head; then lower the sleeve and clamping ring, and gently place them together with the mixing head on the upper surface of the prepared double-layer additive board, so that the axis of the mixing head is evenly divided by the contact interface of the two adjacent additive passes. Set this position as the initial position of the sleeve and the mixing head. Step Six: Simultaneously rotate the sleeve and stirring head to generate friction between their tips and the upper surface of the sheet material. While rotating, the sleeve descends at a constant speed, inserting into the upper layer of the sheet material, while the stirring head rises at a constant speed, leaving the upper surface. This causes the material in the upper layer of the sheet material to undergo plastic deformation again under the stirring friction of the sleeve. After the sleeve and stirring head have descended and risen to certain heights respectively, stop their opposing axial movements and allow them to rotate in place. Through sufficient stirring friction, the gap between the sleeve and stirring head is now completely filled with the thermoplasticized material. Once the plasticized material has completely filled the gap, stop the rotation and quickly move the sleeve and stirring head back to their initial positions. At this point, the plasticized material in the original gap is quickly pressed back, creating protruding "lumps" at the interface between the upper and lower layers of the sheet material. Step 7: The sleeve and stirring head remain on the upper surface of the sheet for a certain period of time. After the material has solidified, they are lifted together with the clamping ring. The resulting protruding "small pieces" can form an overlap and self-locking at the joint interface of the sheet, thereby strengthening a part of the joint interface of the sheet. Step 8: Repeat steps 5 through 7, that is, to form multiple overlaps at the joint of each adjacent pass on the upper layer of the sheet.

2. The stir-friction deposition additive manufacturing method according to claim 1, characterized in that, The sleeve is made of relatively hard tool steel and has threads tapped on the bottom outer surface.

3. The stir-friction deposition additive manufacturing method according to claim 1, characterized in that, The clamping ring is fixed to the outside of the sleeve and serves to clamp and protect it.

4. The stir-friction deposition additive manufacturing method according to claim 1, characterized in that, In step one, the raw material rods loaded are always made of the same material, or different materials may be changed midway through the process.

5. The stir-friction deposition additive manufacturing method according to claim 1, characterized in that, The raw material rods are made of aluminum alloy, magnesium alloy, titanium alloy, or aluminum alloy, magnesium alloy, titanium alloy with composite reinforcing phase.

6. The stir-friction deposition additive manufacturing method according to claim 1, characterized in that, In steps three and four, it is necessary to ensure that the previous deposition layer has been fully cooled and solidified before each additive manufacturing process.

7. The stir-friction deposition additive manufacturing method according to claim 1, characterized in that, Before proceeding to step five, the outer surface of the additive board material must be cleaned.

8. The stir-friction deposition additive manufacturing method according to claim 1, characterized in that, In step six, the height of the sleeve descent and the height of the stirring head elevation should both be less than 25% of the height of a single-layer deposition layer, and after the opposing axial movements of the two stop, the time for in-situ self-rotation should be 0 to 5 seconds.

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