Multi-laser wire feeding additive system and application method thereof

Abstract

The invention discloses a multi-laser wire feeding additive system and an application method thereof, the system is fixed in a machine frame, the machine frame comprises an upper frame and a lower frame, a laser device and an electric control cabinet are arranged in the lower frame, a printing head, a three-axis motion platform and a printing platform are arranged in the upper frame, a wire feeding disc is arranged at the top of the machine frame, and the three-axis motion platform and the printing platform are arranged in the machine frame. The printing head is provided with a split contact tube; and a wire feeding straightening device is arranged at the upper part of the printing head. According to the invention, the functions of automatic gun cleaning and wire shearing, wire straightening, contact tube flexible wire feeding, light spot homogenizing wire feeding, substrate preheating, consistent wire dry elongation and the like can be realized.

Description

Technical Field

[0001] The present invention belongs to a multi-laser wire feeding additive technology, and specifically relates to a multi-laser wire feeding additive system and an application method thereof. Background Art

[0002] Additive manufacturing technology is an advanced digital manufacturing technology that uses the principle of layer-by-layer cladding, arc, laser, electron beam, plasma, etc. as heat sources, and through the continuous addition of metal wires, under the control of the program, metal parts are gradually formed from lines-surfaces-solids according to the three-dimensional digital model. This technology has been applied in aerospace, shipbuilding, military industry, energy and in-situ repair and other fields.

[0003] The laser metal additive manufacturing process uses a direct energy deposition (DED) process that uses a distributed laser source to focus multiple laser beams onto a work surface where the laser focal point intersects the metal material (wire or powder) to form a metal layered structure on the parent material under computer control.

[0004] Prior art 1: A multi-laser beam 3D printing head for metal melting rapid prototyping, announcement number: CN107813050B. It includes a multi-beam annular focusing device and a wire conveying device, the multi-beam annular focusing device includes a spherical arc printing head body, a single beam focusing device distributed in an annular shape, and the wire conveying device includes a wire feeding tube, a driving device, a printing nozzle, a straightening mechanism, etc.; the multi-beam is focused to the center of the spherical arc printing head body through the annularly distributed single beam focusing device; the wire is fed vertically and straightened by the straightening mechanism, which solves the problem of poor wire feeding accuracy caused by wire bending in the existing wire feeding method. The multi-beam annular distribution eliminates the adverse effects of the defocus fluctuation of a single beam on the processing quality during the processing process. The multi-angle beam annular distribution makes it easy to adjust the action angle of the laser beam and the wire and control the laser power. The optical-wire coupling of the device of the present invention is continuous and stable, which significantly improves the processing accuracy and forming efficiency.

[0005] Prior art 2: A laser device replication for multi-laser coaxial wire feeding additive manufacturing equipment, announcement number: CN210817967U. The multiple laser heads of the laser device are arranged along the circumference of the wire feeder, and the laser emitted by the nozzle of the laser head has a set angle with the central axis of the wire feeder, and the angle of the set angle is adjustable. The multiple laser beams emitted by the nozzles of the multiple laser heads converge at the same light spot, and the light spot is located on the central axis of the wire feeder. The multiple laser heads of the laser device are arranged along the circumference of the wire feeder, and the laser emitted by the nozzle of the laser head has a set angle with the central axis of the wire feeder, and the angle of the set angle is adjustable. The multiple laser beams emitted by the nozzles of the multiple laser heads converge at the same light spot, and the light spot is located on the central axis of the wire feeder. The additive manufacturing equipment of the utility model can perform titanium metal 3D printing under inert gas sealing.

[0006] The prior art uses multiple lasers for additive manufacturing, but there are several problems as follows.

[0007] 1. Metal molten ball problem: During the additive manufacturing process, molten balls are easily generated at the end of the wire, affecting the printing quality. In order to more accurately measure the dry elongation of the wire and improve the printing quality, the molten balls need to be removed.

[0008] (II) Inconsistent elongation: In the additive manufacturing process, the elongation of the wire is equal to the length of the wire extending out of the conductive nozzle. In the prior art, the elongation of the wire at different printing starting points is often different, resulting in cumulative errors at different printing starting points, different amounts of wire melt accumulation, and affecting the printing quality.

[0009] (III) Wire bending problem: Wire straightening is required before wire deposition begins. The wire is bent when it extends from the wire feeding nozzle, which is prone to uneven heating and causes splashing and other defects. This will have a great impact on the molding accuracy and the continuity of molding cannot be guaranteed. It needs to be straightened by a straightener.

[0010] (IV) Rigid wire feeding problem: The wire feeding conductive nozzle in the prior art has rigid strength and is prone to wire blockage and wire breakage.

[0011] (V) The energy distribution of multiple laser spots is usually uneven, which affects the printing quality. Summary of the invention

[0012] In order to solve the technical problems existing in the prior art, the present invention provides a multi-laser wire feeding additive system and its application method, including gun cleaning and wire cutting technology, dry elongation detection and control technology, wire straightening technology, split-flap conductive nozzle flexible wire feeding technology and circular, polygonal and other spot uniform energy printing technology.

[0013] A multi-laser wire feeding additive system, the system is fixed in a machine frame, the machine frame includes an upper frame and a lower frame, the laser and the electric control cabinet are arranged in the lower frame, the print head, the three-axis motion platform and the printing platform are arranged in the upper frame, a wire feeding disk is arranged on the top of the machine frame, the print head has a split-type conductive nozzle; a wire feeding straightening device is arranged on the upper part of the print head.

[0014] Furthermore, the wire feeding straightening device is a structure with staggered through holes at different heights, so that the wire can be spirally passed through the straightening device. A motor is connected to the lower part of the straightening device, and the motor is used to drive the straightening device to rotate. During the wire feeding process, the straightening device rotates to achieve straightening of the spirally passing wire.

[0015] Furthermore, the straightening device is a columnar spiral hollow structure, and the hollow structure is a spiral circular through hole.

[0016] Furthermore, the straightening device is a tower-type orifice plate structure, and the tower-type orifice plate structure includes multiple layers of orifice plates, and the orifice plates are supported by orifice plate pillars.

[0017] Furthermore, the wire spiral passes through the through holes of two adjacent layers of perforated plates, and the angle between the through holes of the two adjacent layers of perforated plates in the vertical direction is 126-180 degrees; the number of through holes on the perforated plate is not less than one, and when the number of through holes is two or more, multiple wires can pass through at the same time.

[0018] Furthermore, the diameter of the through hole is 2-4 mm, the diameter of the wire is 0.4-2.0 mm, and the rotation speed of the straightening device is 80-160 rpm.

[0019] Furthermore, the split-type conductive nozzle includes several split ends, a groove portion is formed between the split ends, the upper portion of the split ends is an integrated structure, a locking block is connected to the outer side of the integrated structure, and the locking block provides a flexible locking force for the split ends.

[0020] Furthermore, the printing platform is provided with a heat insulation layer, a heating layer and a substrate in sequence from bottom to top.

[0021] Application method of multi-laser wire feeding additive system, Step 1: Set parameters: set the height H from the print head to the printing platform and set the stem extension L; Step 2: Turn on the power, move the three-axis motion platform to the origin, turn on the laser, focus, and move the printing platform to the focal position of the laser; Step 3: The wire feeding reel starts feeding wire; Step 4: Turn on the laser and protective gas and start printing; The print head can utilize laser pulses to fuse the wire material with a metal molten ball at the end, thereby realizing automatic gun cleaning and wire cutting.

[0022] Furthermore, the wire extending from the conductive nozzle of the print head has a consistent dry extension length at different welding points, and the method for maintaining the consistency includes the following steps: Step 1: Connect the filament and printing platform to the power supply through wires; Step 2: Turn on the power. At this time, the filament does not touch the printing platform, forming a short circuit between the filament and the printing platform. Step 3: The controller controls the wire feeding. When the wire contacts the printing platform, a loop is formed between the wire and the printing platform. The controller receives the electrical signal and controls the wire retraction distance w. The distance H from the print head conductive nozzle to the printing platform is obtained by detection. The dry extension of the wire is known to be L, and the wire retraction distance is w=HL, and the w value range is: 0.05-0.5mm. The distance H from the print head conductive nozzle to the printing platform is completed by laser ranging.

[0023] Furthermore, the laser spot is in the shape of an annular ring, a circle or a polygonal ring, and the method for synthesizing the spot is: first, using multiple arc-shaped, fan-shaped or trapezoidal homogenizing optical fibers to transmit the laser; second, focusing multiple lasers around the wire, adjusting the angle of the homogenizing optical fiber, so that the spot presents an annular ring, a circle or a polygonal ring structure; wherein multiple arc-shaped lasers synthesize an annular spot, multiple fan-shaped lasers synthesize a circular spot, and multiple trapezoidal lasers synthesize a polygonal ring spot.

[0024] The beneficial technical effects of the present invention are as follows: (1) a laser pulse gun cleaning and wire cutting method is used to eliminate the molten ball at the end of the wire during the printing process; (2) a dry extension control method is used to ensure that the dry extension of the wire is consistent at different printing starting points to avoid cumulative errors; (3) a method of forming a circular, circular or regular polygonal light spot using a homogenizing optical fiber to provide uniform light spot energy; (4) a designed split-petal conductive nozzle is used to provide flexible force to the wire to avoid wire breakage or wire blockage; (5) a designed wire straightening device can straighten the wire to avoid problems such as incomplete wire melting and improve printing quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is the front view of the present invention.

[0026] Figure 2 It is a side view of the present invention.

[0027] Figure 3 It is a structural schematic diagram of the three-axis motion platform of the present invention.

[0028] Figure 4 It is a schematic diagram of the structure of the printing platform of the present invention.

[0029] Figure 5 It is a schematic diagram of the vertical cross-sectional structure of the conductive nozzle of the present invention.

[0030] Figure 6 It is a schematic diagram of the top view structure of the conductive nozzle of the present invention.

[0031] Figure 7 It is a structural schematic diagram of embodiment 1 of the straightening device of the present invention.

[0032] Figure 8 It is a structural schematic diagram of embodiment 2 of the straightening device of the present invention.

[0033] In the figure: 1-Laser; 2- Print head; 3-Wire feeding reel; 4-three-axis motion platform; 41-y-axis motion mechanism; 42-x-axis motion mechanism; 43-z-axis motion mechanism; 5-machine frame; 51-upper frame; 52-lower frame; 6- Heating layer; 7- Thermal insulation layer; 8-Drag chain; 9-Electric control cabinet; 10-wire; 11-straightening device; 111-through hole; 112-motor; 113-frame; 114-first wire feeder; 1141-first wire feeder wheel assembly; 115-second wire feeder; 1151-second wire feeder wheel assembly; 116-orifice plate; 117-orifice plate support; 118-frame cover; 119-orifice plate mounting seat; 12-conductive nozzle; 121-locking block; 122-splitting end; 123-groove; 13-Substrate. DETAILED DESCRIPTION

[0034] The technical solution of the present invention will be described clearly and completely below in conjunction with the embodiments and drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the protection scope of the present invention.

[0035] Reference for the implementation of the present invention Figure 1-8 .

[0036] The multi-laser wire feeding additive system includes a machine frame 5, which is divided into an upper frame 51 and a lower frame 52; a laser 1 and an electric control cabinet 9 are arranged inside the lower frame 52; a print head 2, a three-axis motion platform 4 and a printing platform are arranged inside the upper frame 51; and a wire feeding disc 3 is arranged on the top of the machine frame 5.

[0037] The print head 2 is fixedly arranged on the side wall of the upper frame 51. The three-axis motion platform 4 is arranged at the lower part of the print head 2, and includes a y-axis motion mechanism 41, an x-axis motion mechanism 42 arranged on the upper part of the y-axis motion mechanism 41, and a z-axis motion mechanism 43 installed on the side wall of the upper frame 51 on one side of the print head 2. In this embodiment, the three-axis motion platform 4 is a screw mechanism. The screw mechanism can be replaced by a synchronous belt or a gear rack motion mechanism. The three-axis motion platform 4 is connected to the electric control cabinet 9 through a drag chain 8. The three-axis motion platform 4 and the wire feeding reel 3 are controlled by the controller to move and feed wire.

[0038] A printing platform is arranged on the upper part of the x-axis motion mechanism 42. The printing platform includes a heating layer 6, a heat insulating layer 7 and a substrate 13. The heating layer 6 can preheat the substrate 13 in advance, and the heat insulating layer 7 is used to prevent the heat of the heating layer 6 from being transferred to the x-axis motion mechanism 42 and thus affecting its accuracy.

[0039] like Figure 1 , 5 As shown in Figure 6, the print head 2 has a split-type conductive nozzle 12, which includes a plurality of split ends 122. In this embodiment, there are six split ends 122, and there are grooves 123 between the six split ends 122. The upper part of the split ends 122 is an integrated structure, and the integrated structure is threadedly connected to the conductive nozzle locking block 121 on the outside. A spring structure can be arranged between the integrated structure and the locking block 121, and the locking block 121 provides a flexible locking force for the split ends 122.

[0040] like Figure 1 , 7 -8, a wire feeding straightening device 11 is provided on the upper part of the print head 2, and the straightening device 11 is located on the upper part of the print head 2. The straightening device 11 is a structure with staggered through holes 111 at different heights, so that the wire 10 can be spirally passed through the straightening device 11; a motor 112 is connected to the lower part of the straightening device 11, and the motor 112 is used to drive the straightening device 11 to rotate. During the wire threading process, the straightening device 11 rotates to achieve the straightening of the spirally passing wire 10.

[0041] Figure 7A first embodiment of the straightening device 11 is provided. The straightening device 11 is located at the upper part of the print head 2. The straightening device 11 is fixed in the middle of the frame 113. The upper and lower parts of the frame 113 are respectively fixed with a first wire feeder 114 and a second wire feeder 115. The first wire feeder 114 includes a first wire feeder wheel set 1141, and the second wire feeder 115 includes a second wire feeder wheel set 1151. The upper part of the straightening device 11 is connected to the bearing of the first wire feeder 114. The lower part of the straightening device 11 is connected to the motor 112. The straightening device 11 can rotate under the drive of the motor 112, and the speed is 80-160rpm, preferably 100rpm in this embodiment. The wire 10 passes through the first wire feeder wheel set 1141, the straightening device 11, and the second wire feeder wheel set 1151 from top to bottom, and then is sent to the print head 2 and melted onto the substrate 13.

[0042] In this embodiment, the straightening device 11 is a columnar spiral hollow structure. The hollow structure is a spiral stepped circular through hole or a spiral circular through hole. The diameter of the through hole is 2-4 mm, and the diameter of the wire is 0.4-2.0 mm. Therefore, in the process of threading the wire, the wire can be straightened and the problems of wire blocking and wire breaking can be avoided. It is simple, practical and efficient.

[0043] Figure 8 A second embodiment of the straightening device 11 is provided, and the straightening device 11 is a tower orifice plate structure. The straightening device 11 includes multiple layers of orifice plates 116, orifice plate pillars 117 are bolted between the orifice plates 116, and the bottom orifice plate pillars 117 are fixed to the orifice plate mounting seat 119, and a motor 112 is installed at the bottom of the orifice plate mounting seat 119. A frame 113 is fixed at the bottom of the straightening device 11, and the upper part of the straightening device 11 is connected to the frame cover 118 through a bearing. The bottom of the frame 113 is bolted with an installation angle aluminum support and a quick pipe joint.

[0044] During operation, the motor drives the straightening device 11 to rotate at a speed of 80-160 rpm, 100 rpm in this embodiment, and the wire 10 passes through the orifice plate 116 and the quick pipe joint from top to bottom in sequence, and then passes through the print head 2 and melts onto the substrate 13 .

[0045] There are 4-8 holes evenly distributed on the orifice plate 116. The orifice plate 116 can be used to pass through one wire 10, or multiple wires 10, such as 2-4 wires. Each wire 10 passes through the first through hole and the second through hole of two adjacent layers of orifice plates 116, wherein the angle between the first through hole and the second through hole in the vertical direction is 126-180 degrees. It is ensured that the wire is not broken or entangled during the wire threading process. The aperture of the orifice plate 116 is 2-4 mm, and the diameter of the wire is 0.4-2.0 mm.

[0046] Application methods of multi-laser wire feeding additive system: S1: Set parameters: set the height H from the print head 2 to the printing platform, and set the stem extension L; S2: Turn on the power, the three-axis motion platform 4 moves to the origin position, turn on the laser 1, focus, and move the printing platform to the focal length position of the laser; S3: Wire feeding disc 3 starts feeding wire; S4: Turn on the laser and protective gas to start printing.

[0047] The light spot irradiated by the laser 1 onto the substrate 13 is annular, circular or polygonal, and the method for synthesizing the light spot is: first, use multiple arc-shaped, fan-shaped or trapezoidal homogenizing fiber laser mirrors; second, focus the multiple laser mirrors around the wire 10, and adjust the angle of the homogenizing fiber laser mirror to make the light spot present an annular, circular or polygonal ring structure. Multiple arcs are synthesized into annular shapes, multiple fan-shaped shapes are synthesized into a circle, and multiple trapezoids are synthesized into a polygonal ring.

[0048] In the S4 printing process, laser pulse gun cleaning and wire cutting are required at different printing positions, i.e., welding points. That is, the laser pulse generates instantaneous high power to melt the molten ball at the end of the wire 10, thus completing the automatic gun cleaning and wire cutting function.

[0049] In S4, in order to ensure that the dry extension length of the wire 10 at different printing positions, i.e., welding points, remains consistent, the present invention proposes a dry extension length control method for the wire 10. The method comprises the following steps: Step 1: The filament 10 and the printing platform substrate 13 are connected to a power source through wires respectively; Step 2: Turn on the power supply. At this time, the filament 10 does not contact the printing platform substrate 13, and a circuit is formed between the filament and the printing platform substrate 13; Step 3: The controller controls the wire feeding. When the wire 10 contacts the printing platform substrate 13, a loop is formed between the wire and the printing platform substrate 13, and the controller controls the wire 10 to be retracted by a distance w. The distance H (variable) from the conductive nozzle 12 to the substrate printing platform 13 is detected. If the dry extension of the wire 10 is L (fixed value), the wire retraction distance is w=HL, and the w value range is: 0.05-0.5mm.

[0050] The distance H (variable) from the conductive nozzle 12 to the printing platform substrate 13 is completed by laser ranging.

[0051] For those skilled in the art, the above embodiments are exemplary and non-restrictive, and the protection scope of the present invention is not limited by the above embodiments. At the same time, any figure marks in the claims should not be regarded as limiting the protection scope of the claims involved.

[0052] In the description of the present invention, it should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship are based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

Claims

1. A multi-laser wire feeding additive system, wherein the system is fixed in a machine frame, wherein a laser, an electric control cabinet, a print head, a three-axis motion platform, and a printing platform are arranged in the machine frame, and a wire feeding disc is arranged on the top of the machine frame, characterized in that: The printing head has a split-flap conductive nozzle; a wire feeding straightening device is arranged on the upper part of the printing head.

2. The multi-laser wire feeding additive system according to claim 1, characterized in that: The wire feeding straightening device is a structure with staggered through holes at different heights, so that the wire can be spirally passed through the straightening device. A motor is connected to the lower part of the straightening device, and the motor is used to drive the straightening device to rotate. During the wire feeding process, the straightening device rotates to achieve straightening of the spirally passing wire.

3. The multi-laser wire feeding additive system according to claim 2, characterized in that: The straightening device is a columnar spiral hollow structure, and the hollow structure is a spiral circular through hole.

4. The multi-laser wire feeding additive system according to claim 2, characterized in that: The straightening device is a tower-type orifice plate structure, which includes multiple layers of orifice plates, and the orifice plates are supported by orifice plate pillars.

5. The multi-laser wire feeding additive system according to claim 4, characterized in that: The wire spiral passes through the through holes of two adjacent layers of perforated plates, and the angle between the through holes of the two adjacent layers of perforated plates in the vertical direction is 126-180 degrees; the number of through holes on the perforated plate is not less than one, and when the number of through holes is two or more, multiple wires can pass through at the same time.

6. The multi-laser wire feeding additive system according to claim 3 or 5, characterized in that: The diameter of the through hole is 2-4 mm, the diameter of the wire is 0.4-2.0 mm, and the rotation speed of the straightening device is 80-160 rpm.

7. The multi-laser wire feeding additive system according to claim 1, characterized in that: The split-flap conductive nozzle includes a plurality of split ends, a groove portion is formed between the split ends, the upper portion of the split ends is an integrated structure, a locking block is connected to the outer side of the integrated structure, and the locking block provides a flexible locking force for the split ends.

8. The multi-laser wire feeding additive system according to any one of claims 1-5 or 7, characterized in that: The printing platform is sequentially provided with a heat insulating layer, a heating layer and a substrate from bottom to top.

9. An application method of the multi-laser wire feeding additive system according to any one of claims 1 to 5 or 7, characterized in that: Step 1: Set parameters: set the height H from the print head to the printing platform and set the stem extension L; Step 2: Turn on the power, move the three-axis motion platform to the origin, turn on the laser, focus, and move the printing platform to the focal position of the laser; Step 3: The wire feeding reel starts feeding wire; Step 4: Turn on the laser and protective gas and start printing; The print head can utilize laser pulses to fuse the wire material with a metal molten ball at the end, thereby realizing automatic gun cleaning and wire cutting.

10. The application method of the multi-laser wire feeding additive system according to claim 9, characterized in that: The wire material extending from the conductive nozzle of the print head has a consistent dry extension length at different welding points, and the method for maintaining consistency includes the following steps: Step 1: Connect the filament and printing platform to the power supply through wires; Step 2: Turn on the power. At this time, the filament does not touch the printing platform, forming a short circuit between the filament and the printing platform. Step 3: The controller controls the wire feeding. When the wire contacts the printing platform, a loop is formed between the wire and the printing platform. The controller receives the electrical signal and controls the wire retraction distance w. The distance H from the print head conductive nozzle to the printing platform is obtained by detection. The dry extension of the wire is known to be L, and the wire retraction distance is w=HL, and the w value range is: 0.05-0.5mm. The distance H from the print head conductive nozzle to the printing platform is completed by laser ranging.

11. The application method of the multi-laser wire feeding additive system according to claim 9, characterized in that: The laser spot is annular, circular or polygonal, and the method for synthesizing the spot is: first, use multiple arc-shaped, fan-shaped or trapezoidal homogenizing optical fibers to transmit lasers; second, focus the multiple lasers around the wire, adjust the angle of the homogenizing optical fiber, and make the spot present an annular, circular or polygonal structure; wherein multiple arc-shaped lasers synthesize annular spots, multiple fan-shaped lasers synthesize circular spots, and multiple trapezoidal lasers synthesize polygonal spots.

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