A double-barrel stir friction additive machine head and additive manufacturing method

Abstract

This invention discloses a dual-bar friction stir additive manufacturing head and method, relating to the field of advanced manufacturing technology. The device includes a pushing mechanism, a dual-bar rotation drive assembly, a stirring tool, a gas cooling assembly, and two round bars. The pushing mechanism applies an axial pushing force to the two round bars. The stirring tool has guide channels corresponding to the two round bars, forming a cold air flow channel between the inner wall of the guide channels and the outer wall of the round bars. The gas cooling assembly is sleeved on the outside of the stirring tool and has symmetrically arranged air inlets. The stirring tool has multiple cold air inlets and outlets. Cold air enters the cold air flow channel through the air inlets and outlets, flows along the outer circumference of the round bars to form a cooling airflow layer, and is discharged through the cold air outlets. This device improves the feeding stability and cooling uniformity of the round bars, reduces reliance on solid lubricants such as graphite during feeding, and provides a structural basis for continuous deposition with little or no lubrication.

Description

Technical Field

[0001] This invention relates to friction stir additive manufacturing technology, and more particularly to a dual-bar friction stir additive manufacturing head and additive manufacturing method. Background Technology

[0002] Friction stirring additive manufacturing is a solid-phase additive technology that utilizes the frictional heat and plastic deformation heat between a rotating tool and a bar stock to soften the material and deposit it layer by layer. It offers advantages such as being free of pores and thermal cracks, and producing a dense microstructure. When using metal bars as raw materials, precise control of heat generation during the deposition process is crucial to ensuring feed stability and deposition quality.

[0003] Chinese patent CN118385722A discloses a temperature control system for friction stir deposition and its usage method. This system features an axially arranged temperature control channel within a rotating spindle, and a stationary first temperature control component mounted on the spindle. Cooling water at a specific flow rate (0.15 kg / s), pressure (2.5 MPa), and temperature (8 ± 1 °C) is continuously supplied to the temperature control channel via a pressurized water supply system. The cooling water enters the channel inlet in a jet-like manner, thereby achieving precise control of heat generation during the friction stir solid-state deposition process of high-strength steel bars. This technology uses liquid cooling to control the temperature of the spindle and the bar stock, effectively suppressing thermal softening to some extent.

[0004] However, the above scheme has the following defects: (1) Its feeding method is single rod feeding, the material supply rate is limited, the deposition efficiency is low, and it is difficult to meet the high-efficiency forming requirements of large-size components; (2) The use of liquid cooling medium requires a complex sealing structure to prevent coolant leakage and contamination of the deposition area, and the uniformity of jet cooling is difficult to guarantee, and there may be gradient differences in the circumferential temperature field of the rod; (3) The temperature control channel is set inside the rotating spindle, and the cooling effect area is concentrated in the spindle section, which has limited ability to suppress the heat conduction of the entire length of the rod feeding channel, and the rod still has the risk of local preheating and softening before entering the deposition area; (4) In the existing center feeding type stirring friction additive manufacturing, in order to reduce the frictional resistance between the rod and the feeding channel and avoid feeding jamming, it is usually necessary to use solid lubricants such as graphite. Although graphite lubricant can improve the frictional state during the feeding process, it may enter the deposition area with the rod and accumulate at the deposition layer interface, thereby increasing the risk of interlayer defects and affecting the interlayer bonding quality and forming stability. Summary of the Invention

[0005] To address the problems existing in the prior art, the purpose of this invention is to provide a dual-bar stirring friction additive manufacturing head and additive manufacturing method that has high deposition efficiency, better temperature control, and does not require solid lubricants such as graphite.

[0006] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0007] A dual-bar friction stir additive manufacturing head device includes: a pushing mechanism, a dual-bar rotary drive assembly, a stirring tool, a gas cooling assembly, and two round bars; the bottom end of the pushing mechanism abuts against the top ends of the two round bars; the dual-bar rotary drive assembly includes a synchronous transmission mechanism and a rotating spindle, the synchronous transmission mechanism being drively connected to the rotating spindle, and the rotating spindle being drively connected to the stirring tool; the stirring tool has two vertically parallel guide channels, and each round bar passes through a corresponding guide channel, and the guide... An annular gap is formed between the inner wall of the channel and the outer wall of the round bar, which constitutes a cold air flow channel. The gas cooling assembly is sleeved on the outside of the stirring tool. The gas cooling assembly is provided with a first air inlet and a second air inlet arranged symmetrically. The stirring tool has multiple cold air inlets and cold air outlets. The first air inlet and the second air inlet are connected to the cold air flow channel through the cold air inlets. The multiple cold air outlets are connected to the cold air flow channel. The cold air flows along the outer periphery of the round bar through the cold air flow channel to cool the round bar.

[0008] Furthermore, the pushing mechanism also includes a cylinder, an upper pressure head, a bearing seat, a rotating flange, and two push rods; the output end of the cylinder is fixedly connected to the upper pressure head, the upper pressure head is fixedly connected to the bearing seat, a bearing is provided inside the bearing seat, the rotating flange is rotatably installed inside the bearing seat, and each push rod is fixedly connected to the rotating flange and abuts against the top end of a round bar.

[0009] Furthermore, the rotary flange includes a bearing inner ring mating journal and two push rod mounting joints. The bearing inner ring mating journal is tightly fitted with the inner ring of the bearing, and the two push rod mounting joints are fixedly connected to the two push rods one-to-one.

[0010] Furthermore, the synchronous transmission mechanism includes a drive motor, a driving pulley, a synchronous belt, a driven pulley, and a bearing; the drive motor is connected to the driving pulley, the driving pulley is connected to the driven pulley via the synchronous belt, the driven pulley is connected to the rotating main shaft, and the rotating main shaft is rotatably supported by the bearing.

[0011] Furthermore, the stirring tool is provided with a positioning protrusion, which is positioned and engaged with the double-bar rotation drive assembly.

[0012] Furthermore, the outer wall of the stirring tool is cylindrical. The plurality of cold air outlets are located on the circumferential part of the outer wall of the stirring tool, and the plurality of cold air inlets are located on the lower circumferential part of the outer wall of the stirring tool. The plurality of cold air outlets and cold air inlets are arranged at intervals along the circumferential direction of the outer wall of the stirring tool.

[0013] Furthermore, the two round bars are arranged parallel to each other and symmetrically distributed about the central axis of the stirring tool.

[0014] A method for manufacturing additive manufacturing using a dual-bar friction stir process, based on the aforementioned dual-bar friction stir machine head device, includes the following steps:

[0015] S1. Insert the two round bars into the corresponding guide channels respectively, and make the top ends of the two round bars abut against the corresponding push rods respectively.

[0016] S2. Start the double-bar rotation drive assembly, drive the stirring tool to rotate through the rotating main shaft, and make the two bar materials rotate synchronously;

[0017] S3. Cold air is introduced into the cold air passage through the first air inlet and the second air inlet, so that the cold air flows along the outer periphery of the round bar and forms a cooling airflow layer.

[0018] S4. Start the feeding mechanism to feed the two round bars along the axial direction of the double bar guide channel;

[0019] S5. Cold air flows along the outer periphery of the round bar to form a cooling airflow layer. After heat exchange, the cold air is discharged from the cold air outlet. The two round bars are deposited together in the stirring friction area under the stirring tool to form an additive layer.

[0020] Compared with the prior art, the beneficial effects of this invention are:

[0021] 1. The present invention adopts a dual-round bar synchronous feeding structure, which enables two round bars to participate in stirring and friction deposition at the same time. Compared with the single bar feeding method, it improves the material supply and deposition efficiency per unit time.

[0022] 2. The present invention applies axial pushing force to two round bars respectively through a pushing mechanism, and achieves adaptive matching between the pushing end and the rotation state of the round bars through a rotating flange, which is beneficial to improving the stability of the double round bar feeding process.

[0023] 3. The present invention uses round bars as feeding material. Two round bars are respectively inserted into the corresponding guide channels. Compared with the square bar feeding structure, it can reduce the obstruction of material flow by the edges and corners of the bars and reduce the risk of local jamming during the feeding process.

[0024] 4. The present invention sets up a guide channel inside the stirring tool and uses the annular gap between the inner wall of the guide channel and the outer wall of the round bar to form a cold air flow channel, so that the cold air can flow along the outer periphery of the round bar, thereby inhibiting the bar from softening, sticking or being blocked in the stirring friction area in advance, and the temperature control effect is better.

[0025] 5. This invention reduces the risk of friction jamming and thermal softening adhesion of the bar stock during the feeding process by using a double-round bar circular feeding structure in conjunction with an outer gas cooling structure. This reduces the dependence on solid lubricants such as graphite and lowers the possibility of lubricants entering the deposition layer interface and affecting the forming quality. Attached Figure Description

[0026] Figure 1 A schematic diagram of the overall structure of the dual-bar stirring friction additive manufacturing head device provided by the present invention;

[0027] Figure 2 This is a schematic diagram of the feeding mechanism provided by the present invention;

[0028] Figure 3 This is a schematic diagram of the rotating flange structure provided by the present invention;

[0029] Figure 4 This is a schematic diagram of the structure of the double-bar rotation drive assembly provided by the present invention;

[0030] Figure 5 A schematic diagram of the stirring tool provided by the present invention;

[0031] Figure 6 This is a schematic diagram of the gas cooling component structure provided by the present invention;

[0032] Figure 7 This is a partially enlarged schematic diagram of the cold airflow channel provided by the present invention;

[0033] Figure 8 This is a cross-sectional view of the gas cooling assembly and stirring tool provided by the present invention.

[0034] Figure 9 This is a schematic diagram of the formation of the cooling airflow layer provided by the present invention. Detailed Implementation

[0035] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

[0036] Example 1

[0037] like Figure 1 As shown, this embodiment provides a dual-bar friction stir additive manufacturing head device, including a pushing mechanism 1, a dual-bar rotation drive assembly 2, a stirring tool 3, a gas cooling assembly 4, and two round bars 5. The bottom end of the pushing mechanism 1 abuts against the top ends of the two round bars 5, and is used to apply an axial pushing force to the two round bars 5; the dual-bar rotation drive assembly 2 is connected to the stirring tool 3 for driving the stirring tool 3 to rotate, and the two round bars 5 are inserted inside the stirring tool 3; the gas cooling assembly 4 is sleeved on the outside of the stirring tool 3, and is used to supply cold air into the stirring tool 3.

[0038] like Figure 2 As shown, the feeding mechanism 1 includes a cylinder 1-1, an upper pressure head 1-2, a bearing housing 1-3, a rotating flange 1-4, and two push rods 1-5. The output end of the cylinder 1-1 is fixedly connected to the upper pressure head 1-2, and the upper pressure head 1-2 is fixedly connected to the bearing housing 1-3. A bearing is installed inside the bearing housing 1-3, and the rotating flange 1-4 is rotatably installed inside the bearing housing 1-3. The two push rods 1-5 are fixedly connected to the rotating flange 1-4 respectively, and respectively abut against the top end of the corresponding round bar 5.

[0039] During operation, cylinder 1-1 applies downward force through upper pressure head 1-2 and bearing seat 1-3, and two push rods 1-5 respectively push the two round bars 5 axially. Since the rotating flange 1-4 can rotate relative to the bearing seat 1-3, when the round bars 5 are rotating, the rotating flange 1-4 and push rods 1-5 can rotate synchronously with the round bars 5, thereby avoiding the pushing mechanism 1 restricting the rotation of the round bars 5.

[0040] like Figure 3 As shown, the rotating flange 1-4 includes a bearing inner ring mating journal 1-4-1 and two push rod mounting joints 1-4-2. The bearing inner ring mating journal 1-4-1 is installed in conjunction with the bearing inner ring to provide rotational support for the rotating flange 1-4; the two push rod mounting joints 1-4-2 are respectively connected to two push rods 1-5 to achieve synchronous pushing of the two round bars 5.

[0041] like Figure 4 As shown, the double-bar rotary drive assembly 2 includes a drive motor 2-1, a drive pulley 2-2, a synchronous belt 2-3, a driven pulley 2-4, a bearing 2-5, and a rotary spindle 2-6. The drive motor 2-1 is connected to the drive pulley 2-2, which is connected to the driven pulley 2-4 via the synchronous belt 2-3. The driven pulley 2-4 is connected to the rotary spindle 2-6, which is rotatably supported by the bearing 2-5. During operation, the drive motor 2-1 drives the drive pulley 2-2 to rotate, which in turn drives the driven pulley 2-4 and the rotary spindle 2-6 via the synchronous belt 2-3. The rotary spindle 2-6 further drives the stirring tool 3 to rotate.

[0042] like Figure 5As shown, the outer wall of the stirring tool 3 is cylindrical, and it is provided with a positioning protrusion 3-1, two guide channels 3-2, a cold air outlet 3-3, and a cold air inlet 3-4. The positioning protrusion 3-1 is used for positioning and engagement between the stirring tool 3 and the double-bar rotary drive assembly 2. The two guide channels 3-2 are two vertical, parallel cylindrical channels, and the two round bars 5 are respectively inserted into the corresponding guide channels 3-2. The two round bars 5 are arranged parallel to each other and symmetrically distributed about the central axis of the stirring tool 3, so that the two round bars 5 can participate in deposition together in the stirring friction area at the bottom of the stirring tool 3. Multiple cold air outlets 3-3 are provided on the upper circumferential surface of the outer wall of the stirring tool 3, and multiple cold air inlets 3-4 are provided on the lower circumferential surface of the outer wall of the stirring tool 3. The multiple cold air outlets 3-3 and cold air inlets 3-4 are evenly spaced along the circumferential surface of the outer wall of the stirring tool 3.

[0043] In this embodiment, the two round bars 5 have a circular cross-section and are respectively inserted into the two guide channels 3-2. Compared with the feeding method of square bars, the round bars 5 do not have obvious corner interference in the double bar guide channels 3-2, which can reduce the risk of local compression and jamming between the outer periphery of the bar and the inner wall of the channel. This is beneficial to improving the continuous flow state of the material in the stirring tool 3 and reducing the dependence on solid lubricants such as graphite during the feeding process.

[0044] like Figure 6 As shown, the gas cooling assembly 4 is sleeved on the outside of the stirring tool 3. The gas cooling assembly 4 is provided with a first air inlet 4-1 and a second air inlet 4-2. The first air inlet 4-1 and the second air inlet 4-2 are used to connect to an external cold air source and introduce the cold air into the cold air inlet 3-4 inside the stirring tool 3.

[0045] like Figure 7 and Figure 8 As shown, an annular gap is formed between the inner wall of the guide channel 3-2 and the outer wall of the round bar 5, constituting the cold air flow channel 3-5. Cold air enters the gas cooling assembly 4 through the first air inlet 4-1 and the second air inlet 4-2, then enters the cold air flow channel 3-5 through the cold air inlet 3-4 on the stirring tool 3, and flows along the outer circumference of the round bar 5. Because the cold air flow channel 3-5 surrounds the outer circumference of the round bar 5, the cold air can provide enveloping cooling along the feeding path of the round bar 5, thereby reducing the risk of premature softening, adhesion, or feeding obstruction of the round bar 5 before it enters the stirring friction area. Through the synergistic effect of the circular outer circumference structure of the round bar 5 and the cold air flow channel 3-5, the adverse effects of mechanical jamming and thermal softening adhesion on the feeding process can be reduced simultaneously, thereby reducing the need for solid lubricants such as graphite.

[0046] like Figure 9As shown, when the cold air flows around the outer periphery of the round bar 5, it forms a cooling airflow layer, which can continuously cool the outer surface of the round bar 5. After completing the heat exchange, the cold air is discharged from the cold air outlet 3-3, thus forming a cooling path in which the cold air enters, flows along the outer periphery of the bar, and is discharged after heat exchange.

[0047] In this embodiment, the dual-bar rotation drive assembly 2 drives the stirring tool 3 to rotate, and the feeding mechanism 1 applies an axial feeding force to the two round bars 5, causing the two round bars 5 to enter the stirring friction area under the combined action of rotation and axial pressure. At the same time, the gas cooling assembly 4 continuously supplies gas to the cold air passages 3-5 to cool the round bars 5 during the feeding process, thereby achieving the synergistic effect of synchronous feeding, synchronous rotation, co-deposition, and cooling of the feeding area of ​​the two round bars.

[0048] Example 2

[0049] This invention provides a method for manufacturing dual-bar friction stir additive manufacturing, based on the aforementioned dual-bar friction stir additive manufacturing head device, comprising the following steps:

[0050] S1. Insert the two round bars into the corresponding guide channels inside the mixing tool;

[0051] S2. Start the double-bar rotation drive assembly, which drives the mixing tool to rotate through the rotating main shaft, and keeps the two bar materials rotating synchronously.

[0052] S3. Cold air is introduced into the cold air channel through the gas cooling component, so that the cold air flows along the outer periphery of the round bar and forms a cooling airflow layer;

[0053] S4. Start the feeding mechanism so that the two push rods push the corresponding round bar material along the axial direction of the double bar guide channel;

[0054] S5. Cold air flows along the outer periphery of the round bar to form a cooling airflow layer, which reduces the risk of thermal softening and sticking of the round bar during the feeding process and feeding jamming. After heat exchange, the cold air is discharged from the cold air outlet. The two round bars are deposited together in the stirring friction area under the stirring tool to form an additive layer.

[0055] Through the above method, this invention enables the synchronous rotation and co-deposition of two round bars during friction stir additive manufacturing, improving material supply efficiency compared to single-bar feeding. Simultaneously, the formation of a cooling airflow layer around the round bars via gas cooling components and cooling air channels improves temperature control along the feeding path, reducing the risk of premature softening, sticking, and feeding obstruction. Since round bars reduce corner interference and material flow obstruction compared to square bars, this invention also reduces reliance on solid lubricants such as graphite during feeding, thereby reducing the possibility of lubricants entering the deposition layer interface and affecting interlayer bonding quality, thus improving the stability and forming quality of the additive manufacturing process.

[0056] It should be understood that the embodiments and descriptions above are only the principles, main features and advantages of the present invention. Various changes and modifications can be made to the present invention without departing from the spirit and scope of the invention, and all such changes and modifications fall within the protection scope of the present invention.

Claims

1. A dual-bar stirring friction additive manufacturing head device, characterized in that, include: The pusher mechanism (1), the double round bar rotation drive assembly (2), the stirring tool (3), the gas cooling assembly (4), and the two round bars (5); the bottom end of the pusher mechanism (1) abuts against the top end of the two round bars (5) to apply an axial pushing force to the two round bars (5); The dual-bar rotation drive assembly (2) includes a synchronous transmission mechanism and a rotating spindle (2-6). The synchronous transmission mechanism is connected to the rotating spindle (2-6), and the rotating spindle (2-6) is connected to the stirring tool (3). The stirring tool (3) has two vertical, parallel guide channels (3-2). Each bar (5) passes through the corresponding guide channel (3-2), and an annular gap is formed between the inner wall of the guide channel (3-2) and the outer wall of the bar (5). The annular gap constitutes a cold air flow channel (3-5). The gas cooling assembly (4) The gas cooling assembly (4) is fitted on the outside of the mixing tool (3) and is provided with a first air inlet (4-1) and a second air inlet (4-2) arranged symmetrically. The mixing tool (3) is provided with multiple cold air inlets (3-4) and cold air outlets (3-3). The first air inlet (4-1) and the second air inlet (4-2) are connected to the cold air flow channel (3-5) through the cold air inlet (3-4). The multiple cold air outlets (3-3) are connected to the cold air flow channel (3-5). The cold air flows along the outer periphery of the round bar (5) through the cold air flow channel (3-5) to cool the round bar (5).

2. The dual-bar friction stir additive manufacturing head device according to claim 1, characterized in that, The feeding mechanism (1) further includes a cylinder (1-1), an upper pressure head (1-2), a bearing seat (1-3), a rotating flange (1-4), and two push rods (1-5); the output end of the cylinder (1-1) is fixedly connected to the upper pressure head (1-2), the upper pressure head (1-2) is fixedly connected to the bearing seat (1-3), the bearing seat (1-3) is provided with a bearing, the rotating flange (1-4) is rotatably installed in the bearing seat (1-3), and each push rod (1-5) is fixedly connected to the rotating flange (1-4) and abuts against the top end of a round bar (5).

3. The dual-bar friction stir additive manufacturing head device according to claim 2, characterized in that, The rotating flange (1-4) includes a bearing inner ring mating journal (1-4-1) and two push rod mounting joints (1-4-2). The bearing inner ring mating journal (1-4-1) is tightly fitted with the inner ring of the bearing, and the two push rod mounting joints (1-4-2) are fixedly connected to the two push rods (1-5) one-to-one.

4. The dual-bar friction stir additive manufacturing head device according to claim 1, characterized in that, The synchronous transmission mechanism includes a drive motor (2-1), a driving pulley (2-2), a synchronous belt (2-3), a driven pulley (2-4), and a bearing (2-5). The drive motor (2-1) is connected to the driving pulley (2-2), the driving pulley (2-2) is connected to the driven pulley (2-4) via the synchronous belt (2-3), the driven pulley (2-4) is connected to the rotating main shaft (2-6), and the rotating main shaft (2-6) is rotatably supported by the bearing (2-5).

5. The dual-bar friction stir additive manufacturing head device according to claim 1, characterized in that, The stirring tool (3) is provided with a positioning protrusion (3-1), which is positioned and engaged with the double round bar rotation drive assembly (2).

6. The dual-bar friction stir additive manufacturing head device according to claim 1, characterized in that, The outer wall of the stirring tool (3) is cylindrical.

7. The dual-bar friction stir additive manufacturing head device according to claim 6, characterized in that, The plurality of cold air outlets (3-3) are located on the circumferential part of the outer wall of the stirring tool (3), and the plurality of cold air inlets (3-4) are located on the circumferential part of the outer wall of the stirring tool (3).

8. The dual-bar friction stir additive manufacturing head device according to claim 7, characterized in that, The plurality of cold air outlets (3-3) and cold air inlets (3-4) are arranged circumferentially along the outer wall of the stirring tool (3).

9. The dual-bar friction stir additive manufacturing head device according to claim 1, characterized in that, The two round bars (5) are symmetrically distributed about the central axis of the stirring tool (3).

10. A method for manufacturing additive manufacturing using a dual-bar friction stir system, characterized in that, The dual-bar friction stir additive manufacturing head device according to any one of claims 1 to 9 includes the following steps: S1. Insert the two round bars (5) into the corresponding guide channels (3-2) respectively, and make the top ends of the two round bars (5) abut against the corresponding push rods (1-5); S2. Start the double round bar rotation drive assembly (2), drive the stirring tool (3) to rotate through the rotating main shaft (2-6), and make the two round bars (5) rotate synchronously; S3. Cold air is introduced into the cold air passage (3-5) through the first air inlet (4-1) and the second air inlet (4-2), so that the cold air flows along the outer periphery of the round bar (5) and forms a cooling airflow layer; S4. Start the feeding mechanism (1) to feed the two round bars (5) along the axial direction of the double bar guide channel (3-2); S5. Cold air flows along the outer periphery of the round bar (5) to form a cooling airflow layer. After heat exchange, the cold air is discharged from the cold air outlet (3-3). The two round bars (5) are deposited together in the stirring friction area under the stirring tool (3) to form an additive layer.

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