A continuous feeding mechanism for friction stir additive manufacturing

Abstract

The present invention relates to a continuous feeding mechanism for friction stir additive manufacturing, comprising an additive unit, an additive spindle coaxially arranged with the additive unit, and a feeding mechanism coaxially arranged with the additive spindle. The additive unit and the additive spindle are both provided with a spindle inside, a core shaft coaxially arranged in the center of the spindle, and a square hole coaxially arranged in the center of the core shaft adapted to square rods. The feeding mechanism comprises a housing, a feeding drum installed above the housing, a pair of roller feeding devices installed inside the housing, a feeding drive mechanism for driving the pair of roller feeding devices to feed materials, and a spindle driving mechanism for driving the spindle to rotate. The feeding drive mechanism also drives the pair of roller feeding devices and the feeding drum to rotate synchronously. The present invention can achieve continuous, efficient and reliable processing of friction stir additives. It has a compact structure, a reasonable design, is not prone to mechanical failure, can effectively avoid processing interruptions, and improves the stability of the equipment.

Description

Technical Field

[0001] The invention relates to a continuous feeding mechanism for friction stir additive manufacturing, belonging to the technical field of friction stir additive manufacturing. Background Art

[0002] Additive manufacturing uses a material stacking and superposition processing method. Compared with traditional material removal processing methods (such as cutting), it is a new "bottom-up" forming processing method.

[0003] Common additive manufacturing technologies include laser powder sintering, electron beam powder sintering, fused deposition modeling, and friction stir solid-state additive manufacturing. Friction stir additive manufacturing is a solid-phase additive technology developed based on friction stir welding. A friction stir tool frictionally deposits the material at high speeds. Under the action of friction and extrusion, the shaped metal is deposited onto the substrate. As the process progresses, the deposited material accumulates layer by layer until the three-dimensional part is completed. Friction stir additive manufacturing is environmentally friendly, does not require shielding gas, and produces excellent part performance and uniform microstructure.

[0004] At present, the cladding materials in friction stir additive processing mainly come in the form of metal bars, metal wires, etc.

[0005] Additive metal is in the form of bar stock, clamped to the machine tool's spindle. During machining, the bar and spindle rotate synchronously at high speed, while the lower end of the bar contacts and squeezes the metal of the machine, creating the additive process. This method uses a relatively simple machine structure, requiring the square bar to be pre-clamped within the spindle. Because the bar rotates with the spindle, continuous feeding during machining is impossible using existing technology. Furthermore, bar length is limited by factors such as machine size and drive force, making continuous machining impossible.

[0006] Additive metal is in filamentary form: a wire is fed through a wire feeder external to the spindle, typically with a diameter of less than 3mm. Limited by the diameter of the cladding metal, cladding efficiency is low. Due to the small diameter of the wire, the wire feed hole at the cladding interface of the equipment is easily blocked by the shaped metal during friction and extrusion, making it difficult to clean and causing processing interruptions.

[0007] After fully comparing several forms of cladding metal materials, it was found that without a continuous feeding system, the market prospects of friction stir additive manufacturing technology would be limited. Therefore, a continuous feeding mechanism for friction stir additive manufacturing was developed. Summary of the Invention

[0008] In view of the shortcomings of the existing technology, the present invention provides a continuous feeding mechanism for stir friction additive manufacturing. The specific technical solution is as follows:

[0009] A continuous feeding mechanism for stir friction additive manufacturing is used to feed plate-shaped square rods. The continuous feeding mechanism for stir friction additive manufacturing includes an additive unit, an additive spindle coaxially arranged with the additive unit, and a feeding mechanism coaxially arranged with the additive spindle. The additive unit and the additive spindle are both provided with a spindle inside, and a core shaft is coaxially arranged at the center of the spindle, and a square hole adapted for the square rod is coaxially arranged at the center of the core shaft; the feeding mechanism includes an outer shell, a feeding drum installed above the outer shell, a roller feeding device installed inside the outer shell, a feeding drive mechanism for driving the roller feeding device to feed, and a spindle drive mechanism for driving the spindle to rotate. The feeding drive mechanism also drives the roller feeding device and the feeding drum to rotate synchronously.

[0010] As a further improvement, a rotating platform is provided below the two sets of extrusion rollers, the roller seats of the extrusion rollers are fixedly mounted on the rotating platform, and the rotating platform is fixedly connected to the core shaft; the lower end of the shell is fixedly mounted on the rotating platform.

[0011] As a further improvement, the double-roller feeding device includes two groups of extrusion rollers arranged opposite to each other, and a square bar passing space for square bars to pass through is provided between the two groups of extrusion rollers. The feeding cylinder is located above the square bar passing space and the lower end of the feeding cylinder is connected to the square bar passing space. The square hole is located below the square bar passing space and the square hole is connected to the square bar passing space.

[0012] A further improvement is that the feeding drive mechanism includes a first gear coaxially connected to the extrusion roller, a second gear externally meshed with the first gear, a side bevel gear coaxially connected to the second gear, a first pulley, a first transmission belt adapted to the first pulley, a second pulley adapted to the first transmission belt, and a first servo motor for driving the second pulley to rotate. A lower bevel gear is arranged between the two sets of side bevel gears, and both sets of side bevel gears are meshed with the lower bevel gear. The lower bevel gear is rotatably connected to the main shaft, and the wheel seat of the side bevel gear is fixedly connected to the rotating platform; the second pulley and the first pulley are connected by a first transmission belt, the first pulley is sleeved on the outside of the main shaft, the first pulley is rotatably connected to the main shaft, and the first pulley is fixedly connected to the lower bevel gear.

[0013] A further improvement is that the spindle drive mechanism includes a third pulley coaxially connected to the spindle, a second transmission belt adapted to the third pulley, a fourth pulley adapted to the second transmission belt, and a second servo motor for driving the fourth pulley to rotate, and the fourth pulley is connected to the third pulley through a second transmission belt.

[0014] As a further improvement, there is a speed difference between the speed of the main shaft and the speed of the lower bevel gear.

[0015] A further improvement further includes a mounting plate, and the additive spindle also includes an outer cylinder sleeved on the outside of the spindle, the outer cylinder is rotatably connected to the spindle, and the outer cylinder is fixedly connected to the mounting plate.

[0016] As a further improvement, the speed difference between the speed of the main shaft and the speed of the lower bevel gear is ΔV, 0 r / min<ΔV≤200 r / min.

[0017] As a further improvement, the first servo motor and the second servo motor are both fixedly mounted on one side of the mounting plate.

[0018] As a further improvement, the cross section of the feed barrel is a square ring structure, and the cross section of the inner ring of the feed barrel is arranged to decrease successively from top to bottom.

[0019] Beneficial effects of the present invention:

[0020] The continuous feeding mechanism for stir friction additive manufacturing described in the present invention can realize continuous, efficient and reliable processing of stir friction additive manufacturing. It has a compact structure and reasonable design, is not prone to mechanical failure, can effectively avoid processing interruptions, improves the stability of the equipment, and creates the necessary prerequisites for the industrialization of stir friction additive manufacturing. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a three-dimensional structural diagram of the continuous feeding mechanism for friction stir additive manufacturing according to the present invention;

[0022] Figure 2 This is a schematic structural diagram of the continuous feeding mechanism for friction stir additive manufacturing according to the present invention;

[0023] Figure 3 This is an internal cross-sectional view of the continuous feeding mechanism for friction stir additive manufacturing according to the present invention. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0025] In the description of the present invention, it should be noted that, unless otherwise specified, "plurality" means two or more; the terms "upper," "lower," "left," "right," "inner," "outer," "front end," "rear end," "head," "tail," etc., indicating directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings and are intended only to facilitate the description of the present invention and simplify the description. They do not indicate or imply that the devices or components referred to must have a specific direction, be constructed, or operate in a specific direction, and therefore should not be construed as limiting the present invention. Furthermore, the terms "first," "second," "third," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0026] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed, detachable, or integral connections; mechanical or electrical connections; direct or indirect connections through an intermediate medium; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on the specific circumstances.

[0027] Example 1

[0028] like Figures 1 to 3 As shown, the continuous feeding mechanism for stir friction additive manufacturing is used to feed the plate-shaped square rod 40. The continuous feeding mechanism for stir friction additive manufacturing includes an additive unit 12, an additive spindle 11 coaxially arranged with the additive unit 12, and a feeding mechanism coaxially arranged with the additive spindle 11. The additive unit 12 and the additive spindle 11 are both provided with a spindle 111 inside, and the center of the spindle 111 is coaxially provided with a core shaft 13, and the center of the core shaft 13 is coaxially provided with a square hole adapted to the square rod 40; the feeding mechanism includes a shell 21, a feeding drum 22 installed above the shell 21, a roller feeding device installed inside the shell 21, a feeding drive mechanism for driving the roller feeding device to feed, and a spindle drive mechanism for driving the spindle 111 to rotate, and the feeding drive mechanism also drives the roller feeding device and the feeding drum 22 to rotate synchronously.

[0029] A rotating platform 37 is provided below the two sets of extrusion rollers 25. The roller seats of the extrusion rollers 25 are fixedly mounted on the rotating platform 37. The rotating platform 37 is fixedly connected to the core shaft 13. The lower end of the housing 21 is fixedly mounted on the rotating platform 37. The roller shafts of the extrusion rollers 25 are rotatably connected to the roller seats of the extrusion rollers 25.

[0030] In some embodiments, to ensure sufficient extrusion force and stroke, the extrusion rollers 25 can be arranged into four groups (arranged into two pairs), six groups (arranged into three pairs), eight groups (arranged into four pairs), etc.

[0031] The double-roller feeding device includes two groups of extrusion rollers 25 arranged opposite to each other, and a square bar passing space for the square bar 40 to pass through is provided between the two groups of extrusion rollers 25. The feeding cylinder 22 is located above the square bar passing space and the lower end of the feeding cylinder 22 is connected to the square bar passing space. The square hole is located below the square bar passing space and the square hole is connected to the square bar passing space.

[0032] The feeding drive mechanism includes a first gear 23 coaxially connected to the extrusion roller 25, a second gear 24 externally meshed with the first gear 23, a side bevel gear 36 coaxially connected to the second gear 24, a first pulley 34, a first transmission belt 33 adapted to the first pulley 34, a second pulley 32 adapted to the first transmission belt 33, and a first servo motor 31 for driving the second pulley 32 to rotate. A lower bevel gear 35 is provided between the two sets of side bevel gears 36, and both sets of side bevel gears 36 are meshed with the lower bevel gear 35. The lower bevel gear 35 is rotatably connected to the main shaft 111, and the wheel seat of the side bevel gear 36 is fixedly connected to the rotating platform 37; the second pulley 32 and the first pulley 34 are connected by a first transmission belt 33, the first pulley 34 is sleeved on the outside of the main shaft 111, the first pulley 34 is rotatably connected to the main shaft 111, and the first pulley 34 is fixedly connected to the lower bevel gear 35. The wheel shaft of the side bevel gear 36 is rotatably connected to the wheel seat of the side bevel gear 36 .

[0033] The spindle drive mechanism includes a third pulley 54 coaxially connected to the spindle 111, a second transmission belt 53 adapted to the third pulley 54, a fourth pulley 52 adapted to the second transmission belt 53, and a second servo motor 51 for driving the fourth pulley 52 to rotate. The fourth pulley 52 is connected to the third pulley 54 via a second transmission belt 53.

[0034] The feed barrel 22 and the roller feeding device rotate together with the main shaft 111. The main shaft 111 and the additive unit 12 are distributed up and down, and the additive unit 12 is matched with the additive equipment. The square bar is put into the feed barrel 22 manually or by a robot. Once the square bar enters the feed barrel 22, it moves downward by its own weight and rotates with the feed barrel 22 and the main shaft 111. When the square bar comes down and touches the top of the two extrusion rollers 25, it is squeezed and transported downward by the extrusion rollers 25. The downward forging force of the square bar is determined by the amount of extrusion between the extrusion rollers 25 and the square bar. New square bars can be continuously added above the feed barrel 22. As the processing progresses, the cladding raw material (square bar) is continuously consumed and moved downward, realizing an uninterrupted supply of cladding raw material and ensuring the continuity of the automatic feeding process.

[0035] The extrusion roller 25 is driven by the first gear 23 , the first gear 23 is driven by the side bevel gear 36 through the second gear 24 , and the two side bevel gears 36 are driven by a lower bevel gear 35 , thereby meeting the synchronization of the two extrusion rollers 25 .

[0036] The first servo motor 31 drives the lower bevel gear 35 to rotate through the second pulley 32 , the first transmission belt 33 , and the first pulley 34 .

[0037] The second servo motor 51 drives the main shaft 111 to rotate through the fourth pulley 52, the second transmission belt 53, and the third pulley 54. There must be a speed difference between the rotation speed of the main shaft 111 and the rotation speed of the lower bevel gear 35. This speed difference will drive the rotation of the extrusion roller 25 and squeeze the square bar to move downward. In the processing state, the main shaft 111 drives the additive unit 12 to rotate at high speed, and the square bar also rotates at high speed and moves downward with the main shaft 111 and the additive unit 12. The square bar is squeezed out of the square hole by the extrusion force of the upper roller feeding device and rotates with the main shaft 111. While the raw material generates heat by extrusion and friction on the surface of the substrate, it obtains heat energy for the second time under the action of the re-extrusion and friction between the shaft shoulder and the body material, thereby enhancing the fluidity and structural uniformity of the cladding metal and achieving high-quality connection.

[0038] Example 2

[0039] Based on Example 1, the continuous feeding mechanism for friction stir additive manufacturing further includes a mounting plate 10, and the additive spindle 11 further includes an outer cylinder 112 sleeved on the outside of the spindle 111, the outer cylinder 112 being rotatably connected to the spindle 111, and the outer cylinder 112 being fixedly connected to the mounting plate 10. The first servo motor 31 and the second servo motor 51 are both fixedly mounted on one side of the mounting plate 10.

[0040] The mounting plate 10 is fixed and driven by a motor and a belt, and the speed difference is used to ensure continuous feeding in a limited space (rotating platform 37 and its vicinity). The relative rotation connection is completed by installing bearings.

[0041] Example 3

[0042] In order to facilitate feeding and minimize collisions, the cross section of the feeding barrel 22 is a square ring structure, and the cross section of the inner ring of the feeding barrel 22 is set to decrease from top to bottom.

[0043] Example 4

[0044] The square bar material is a 6XXX aluminum alloy bar material with a cross-sectional diameter of 10 mm.

[0045] Start the equipment, set the pre-pressure of the roller feeding device on the square bar to 200 kgf, and the spindle speed of the stir friction additive equipment to 800 RPM (the speed of the spindle 111 is 800 RPM).

[0046] The additive process speed is 60mm / min, and the additive path is a 200×200mm square profile. After the friction stir additive machine completes a single additive pass and moves to the initial additive position, its spindle speed remains unchanged, while the roller feeder continues to apply pressure. Simultaneously, the head of the additive unit 12 slowly moves upward, initiating the second layer of cladding along the additive path. When the shoulder end face of the friction stir additive machine is 2mm above the first layer of cladding material, the head stops moving upward and continues to advance steadily along the additive path. Finally, after the fifth layer of additive processing is completed, the mechanism is lifted and returned to its parking position, completing the additive process.

[0047] Example 5

[0048] The speed difference between the speed of the main shaft 111 and the speed of the lower bevel gear 35 is ΔV, 0 r / min<ΔV≤200 r / min.

[0049] In the present invention, the size of ΔV determines the additive material travel speed. If ΔV is too small, the additive material travel speed will become smaller. When ΔV=0, the additive material travel speed=0; but if ΔV is too large, slippage is very likely to occur between the square rod and the extrusion roller 25.

[0050] Specifically, when ΔV is 50r / min, 56r / min, 60r / min, 65r / min, and 70r / min, the additive travel speed and whether continuous feeding occurs slippage are shown in Table 1:

[0051] Table 1

[0052]

[0053] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A continuous feeding mechanism for friction stir additive manufacturing, used for feeding plate-shaped square rods (40), the continuous feeding mechanism for friction stir additive manufacturing comprising an additive unit (12), characterized in that: It also includes an additive spindle (11) coaxially arranged with the additive unit (12) and a feeding mechanism coaxially arranged with the additive spindle (11), wherein the additive unit (12) and the additive spindle (11) are both provided with a spindle (111), a core shaft (13) is coaxially arranged at the center of the spindle (111), and a square hole adapted to the square bar (40) is coaxially arranged at the center of the core shaft (13); the feeding mechanism includes a housing (21), a feeding cylinder (22) installed above the housing (21), a roller feeding device installed inside the housing (21), a feeding drive mechanism for driving the roller feeding device to feed, and a spindle driving mechanism for driving the spindle (111) to rotate, wherein the feeding drive mechanism also drives the roller feeding device and the feeding cylinder (22) to rotate synchronously; A rotating platform (37) is provided below the two groups of extrusion rollers (25), the roller seats of the extrusion rollers (25) are fixedly mounted on the rotating platform (37), and the rotating platform (37) is fixedly connected to the core shaft (13); the lower end of the housing (21) is fixedly mounted on the rotating platform (37); The roller feeding device includes two groups of extrusion rollers (25) arranged opposite to each other, a square bar passage space for the square bar (40) to pass through is provided between the two groups of extrusion rollers (25), the feed cylinder (22) is located above the square bar passage space and the lower end of the feed cylinder (22) is connected to the square bar passage space, the square hole is located below the square bar passage space and the square hole is connected to the square bar passage space; The feeding drive mechanism comprises a first gear (23) coaxially connected to the extrusion roller (25), a second gear (24) externally meshed with the first gear (23), a side bevel gear (36) coaxially connected to the second gear (24), a first pulley (34), a first transmission belt (33) adapted to the first pulley (34), a second pulley (32) adapted to the first transmission belt (33), and a first servo motor (31) for driving the second pulley (32) to rotate. A lower bevel gear (36) is provided between the two sets of side bevel gears (36). 5), both sets of side bevel gears (36) are meshed with the lower bevel gear (35), the lower bevel gear (35) is rotatably connected to the main shaft (111), and the wheel seat of the side bevel gear (36) is fixedly connected to the rotating platform (37); the second pulley (32) and the first pulley (34) are connected through a first transmission belt (33), the first pulley (34) is sleeved on the outside of the main shaft (111), the first pulley (34) is rotatably connected to the main shaft (111), and the first pulley (34) is fixedly connected to the lower bevel gear (35); There is a speed difference between the speed of the main shaft (111) and the speed of the lower bevel gear (35).

2. A continuous feeding mechanism for friction stir additive manufacturing according to claim 1, characterized in that: The spindle drive mechanism comprises a third pulley (54) coaxially connected to the spindle (111), a second transmission belt (53) adapted to the third pulley (54), a fourth pulley (52) adapted to the second transmission belt (53), and a second servo motor (51) for driving the fourth pulley (52) to rotate, wherein the fourth pulley (52) and the third pulley (54) are connected via the second transmission belt (53).

3. The continuous feeding mechanism for friction stir additive manufacturing according to claim 1, characterized in that: The speed difference between the speed of the main shaft (111) and the speed of the lower bevel gear (35) is ΔV, 0 r / min<ΔV≤200 r / min.

4. The continuous feeding mechanism for friction stir additive manufacturing according to claim 2, characterized in that: It also includes a mounting plate (10), and the additive spindle (11) also includes an outer cylinder (112) sleeved on the outside of the spindle (111), the outer cylinder (112) is rotatably connected to the spindle (111), and the outer cylinder (112) is fixedly connected to the mounting plate (10).

5. The continuous feeding mechanism for friction stir additive manufacturing according to claim 4, characterized in that: The first servo motor (31) and the second servo motor (51) are both fixedly mounted on one side of the mounting plate (10).

6. The continuous feeding mechanism for friction stir additive manufacturing according to claim 1, characterized in that: The cross section of the feeding barrel (22) is a square ring structure, and the cross section of the inner ring of the feeding barrel (22) is arranged to decrease in sequence from top to bottom.

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