Layer-by-layer optimization system and method for inner wall of laser additive forming through cavity

Abstract

The invention discloses a layer-by-layer optimization system for the inner wall of a laser additive forming through cavity. The layer-by-layer optimization system comprises a laser device, a forming substrate and a layer-by-layer optimization device for the inner contour of the through cavity, wherein the laser device can do XYZ movement and has a downward laser head; an enclosing wall is arranged on the periphery of the base plate, and a forming groove is formed in the enclosing wall; a laser device melts and solidifies a preset area of the metal powder layer laid in the forming groove, so that a metal solidification layer with an inner contour is formed in the preset area, and a clear inner contour is optimized along the edge of the inner contour of the metal solidification layer through the cavity inner contour layer-by-layer optimization device; and the inner wall surface of the vertical through cavity of the finally formed target forming part is uniform and smooth and is not easy to crack.

Description

Technical Field

[0001] The invention belongs to the field of laser layer-by-layer additive manufacturing. Background Art

[0002] The working principle of laser additive manufacturing technology is to use a high-power laser beam to accurately melt metal powder. After the laser beam scans the surface of the metal powder layer, it melts the material locally by rapid heating, and quickly solidifies during the cooling process to form a metal solidification layer. The metal solidification layer is stacked layer by layer until the desired object is formed;

[0003] Since there are a large number of metal sintered particle bands on the contour edge of the solidified layer, which are formed by melting metal powder and gathering into droplets and then rapidly solidifying, the contour line of the contour edge is unclear. Therefore, the surface of the final molded product of laser additive manufacturing generally has a large number of small pits and burrs, and the surface stress is uneven; the existing treatment method is to use surface grinding and surface shot peening processes after molding to eliminate surface stress and burrs, and avoid the formation of a large number of burrs and later cracks on the surface of the final molded parts; when the final molded object has a through inner cavity, the inner wall of the cavity is not convenient for grinding and shot peening processes, especially not suitable for shot peening processes. Summary of the invention

[0004] Purpose of the invention: In order to overcome the deficiencies in the prior art, the present invention provides a layer-by-layer optimization system for the inner wall of a through-cavity in laser additive forming, so that the inner wall surface of the vertical through-cavity of the target molded part finally formed is homogeneous, smooth and not prone to cracking.

[0005] Technical solution: To achieve the above-mentioned purpose, the layer-by-layer optimization system of the inner wall of the through-cavity of the laser additive forming of the present invention comprises a laser device with a laser head facing downward and capable of XYZ movement, a molding substrate and a layer-by-layer optimization device for the inner contour of the through-cavity; the substrate has an enclosing wall on the outer periphery, and the inner part of the enclosing wall is a molding groove; the laser device melts a preset area of ​​the metal powder layer laid in the molding groove and then solidifies it, so that the preset area forms a metal solidification layer with an inner contour, and the layer-by-layer optimization device for the inner contour of the through-cavity optimizes a clear inner contour along the inner contour edge of the metal solidification layer.

[0006] Furthermore, a downwardly extending sinking cylinder is integrally provided in the center of the forming substrate, and a metal powder pre-filling bin is contained in the sinking cylinder; the metal powder pre-filling bin is pre-filled with metal powder to form a pre-filling bin metal powder filling body.

[0007] Furthermore, the device for optimizing the inner contour of the through-cavity layer by layer includes a rotating disk coaxially arranged at the bottom end of the sinking cylinder.

[0008] Furthermore, the layer-by-layer optimization device for the inner contour of the through-cavity also includes an upwardly extending vertical rod fixedly connected to the upper end of the rotating disc coaxially, the vertical rod upwardly coaxially passes through the metal powder pre-filling bin, and passes upwardly to the top end higher than the molding groove; lifters are fixedly installed on both sides of the vertical rod, the upper end of the lifting rod of the lifter is fixedly connected to a steering gear seat, a swing arm steering gear is installed on the steering gear seat, a telescopic arm is vertically connected to the transverse steering gear shaft of the swing arm steering gear, a motor is vertically fixedly installed at the end of the telescopic part of the telescopic arm, and a rotating cone head is coaxially connected to the output end of the motor;

[0009] A b motor is installed on the lower side of the edge of the rotating disc, and a b rotating cone head with a pointed head facing upward is arranged on the upper side of the edge of the rotating disc. The b motor can drive the b rotating cone head to rotate;

[0010] An alloy wire passing slot extending in the vertical direction is hollowed out on the vertical pole, and a horizontal alloy wire restraining rod is fixedly arranged on the upper end of the alloy wire passing slot;

[0011] It also includes a hard alloy fine twist rope, which obliquely passes through the alloy wire passing groove, and the upper and lower ends of the hard alloy fine twist rope are respectively fixedly connected to the tip of the rotating cone head a and the tip of the rotating cone head b.

[0012] Furthermore, the axis of the a motor is perpendicular to the axis of the lateral steering gear shaft.

[0013] Furthermore, the cross-sectional outer diameter of the cemented carbide fine-twist rope ranges from 1.5 mm to 2.5 mm.

[0014] Furthermore, the hard alloy fine twist rope is formed by twisting a plurality of hard alloy wires.

[0015] Further, the optimization process of the layer-by-layer optimization system of the laser additive forming through-cavity inner wall is as follows:

[0016] Step 1: In the initial state, the telescopic arm is vertically facing upward, and the hard alloy fine twist rope is stretched across the lower side of the alloy wire restraint rod;

[0017] Step 2: Laying a thin layer of metal powder of a preset thickness in the forming tank;

[0018] Step 3, controlling the laser device to form a metal solidification layer with an inner contour formed by solidification of molten metal in the central area of ​​the uppermost metal powder thin layer in the forming groove;

[0019] Step 4, control the originally vertical telescopic arm to swing downward clockwise around the horizontal servo shaft, and the telescopic part of the telescopic arm extends adaptively, so that the carbide fine twist rope maintains tension while the carbide fine twist rope forms a local bend at the contact position with the inner contour edge of the top metal solidification layer, and the local bending position of the carbide fine twist rope is recorded as the local bending part of the carbide fine twist rope; at this time, the tip of the rotating cone head a and the tip of the rotating cone head b are controlled to rotate at the same speed and the same rotation direction, so that any cross-section of the taut carbide fine twist rope at this time rotates along its own center, and the carbide fine twist rope maintains a stable tension while the disc drive motor is controlled to drive the rotating disc to rotate at least one circle along the axis.

[0020] Beneficial effects: Each layer of metal solidification layer of the present invention is made more dense and uniform by the rolling of the inner contour edge under the local bending part of the hard alloy fine twist rope, eliminating the local surface stress, and peeling off the metal sintered particles. The boundary of the contour line of the inner contour edge is clear and smooth; therefore, the inner wall surface of the vertical through cavity of the target molded part finally formed is homogeneous, smooth, not easy to crack, and does not have a large number of irregular pits, protrusions and burrs. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a schematic diagram of the "Step 1", "Step 2" and "Step 7" stages of this solution. The pre-filled metal powder filling body, the outer powder filling body and the inner powder filling body are hidden in this figure.

[0022] Figure 2 A device for layer-by-layer optimization of the inner contour of the through-cavity;

[0023] Figure 3 for" Figure 1 ” The cross-sectional view in the state shown below;

[0024] Figure 4 for Figure 3 The front view includes a pre-filled metal powder filling body, a peripheral powder filling body, and an inner peripheral powder filling body;

[0025] Figure 5 It is the state when the target molded part is about to be taken out after molding is completed;

[0026] Figure 6 It is a schematic diagram of the process in which a large number of metal sintered particle belts, which are formed by melting metal powder into droplets and then solidifying rapidly, are rolled by the local bending part of a cemented carbide fine-twisted rope at the contour edge of the solidified layer. DETAILED DESCRIPTION

[0027] The present invention will be further described below in conjunction with the accompanying drawings.

[0028] There is a vertical through cavity 18 running longitudinally through the center of the target molded part 22 a of this solution, and the quality enhancement object of the core content of this solution is the inner wall surface of the vertical through cavity 18 .

[0029] As attached Figures 1 to 6 The layer-by-layer optimization system for the inner wall of a through-cavity formed by laser additive manufacturing shown in the figure comprises a laser device 3 with a laser head 2 capable of XYZ movement and facing downward, a molding substrate 9 and a layer-by-layer optimization device 51 for the inner contour of the through-cavity; the substrate 9 has an enclosure wall 17 on its periphery, and a molding groove 7 is inside the enclosure wall 17; the laser device 3 melts a preset area of ​​a metal powder layer laid in the molding groove 7 and then solidifies it, so that a metal solidification layer 22 with an inner contour is formed in the preset area, and the layer-by-layer optimization device 51 for the inner contour of the through-cavity optimizes a clear inner contour along the inner contour edge 20 of the metal solidification layer 22.

[0030] like Figure 1 As shown, a downwardly extending sinking cylinder 15 is integrally provided in the center of the forming substrate 9, and a metal powder pre-filling bin 10 is provided in the sinking cylinder 15; the metal powder pre-filling bin 10 is pre-filled with metal powder to form a pre-filling bin metal powder filling body 10a; the through-cavity inner contour layer-by-layer optimization device 51 includes a rotating disk 11 coaxially arranged at the bottom end of the sinking cylinder 15, and a disk driving motor 12 is arranged below the rotating disk 11, and the disk driving motor 12 can drive the rotating disk 11 to rotate along the axis.

[0031] The upper end of the rotating disc 11 is coaxially fixedly connected to the vertical rod 8 extending upward, the vertical rod 8 passes through the metal powder pre-filling bin 10 upward coaxially, and passes upward to the top end higher than the forming groove 7; the lifters 1 are fixedly installed on both sides of the vertical rod 8, the upper end of the lifting rod 1a of the lifter 1 is fixedly connected to the steering gear seat 27, the steering gear seat 27 is installed with a swing arm steering gear 4, the transverse steering gear shaft 28 of the swing arm steering gear 4 is vertically connected to the telescopic arm 5, the end of the telescopic part 5a of the telescopic arm 5 is vertically fixedly installed with an a motor 23, the axis of the a motor 23 is perpendicular to the axis of the transverse steering gear shaft 28; the output end of the a motor 23 is coaxially connected to a rotating cone head 6.

[0032] A b motor 13 is installed on the lower side of the edge of the rotating disk 11, and a b rotating cone head 14 with a pointed head facing upward is arranged on the upper side of the edge of the rotating disk 11, and the b motor 13 can drive the b rotating cone head 14 to rotate; an alloy wire passing groove 24 extending in the vertical direction is hollowed out on the vertical pole 8, and a horizontal alloy wire restraint rod 16 is fixedly arranged on the upper end of the alloy wire passing groove 24; it also includes a hard alloy fine twist rope 19 twisted by a plurality of hard alloy wires, the hard alloy fine twist rope 19 obliquely passes through the alloy wire passing groove 24, and the upper and lower ends of the hard alloy fine twist rope 19 are respectively fixedly connected to the tip of the a rotating cone head 6 and the tip of the b rotating cone head 14; the outer diameter range of the cross-sectional profile of the hard alloy fine twist rope 19 is 1.5mm to 2.5mm.

[0033] Specific process and process principle description:

[0034] The target molded part 22a of this scheme has a vertical through cavity 18 running longitudinally through the center. The core quality enhancement object of this scheme is the inner wall surface of the vertical through cavity 18.

[0035] Step 1: In the initial state, the metal powder pre-filling bin 10 is pre-filled with metal powder to form a pre-filling bin metal powder filling body 10a, the upper surface of the pre-filling bin metal powder filling body 10a is flush with the surface of the substrate 9, and in the initial state, the telescopic arm 5 is vertically upward, the carbide fine twist rope 19 is stretched across the lower side of the alloy wire constraint rod 16, and the upper section of the carbide fine twist rope 19 tends to be vertical; so that in a top-down perspective, the telescopic arm 5, the a rotating cone head 6 and the carbide fine twist rope 19 are all within the enclosed range of the vertical through cavity 18 that is ultimately to be formed, avoiding motion interference between the necessary displacement path of the laser device 3 and the telescopic arm 5, the a rotating cone head 6 and the carbide fine twist rope 19 in the subsequent "step three" process;

[0036] Step 2: evenly spread a metal powder thin layer of a preset thickness on the common upper surface of the substrate 9 and the pre-filled metal powder filling body 10a;

[0037] Step three, by controlling the XYZ displacement of the laser device 3, the laser device 3 accurately irradiates the laser beam on the topmost metal powder thin layer in the molding groove 7, and by controlling the horizontal displacement of the laser device 3, the scanning range and path of the laser beam are controlled, and finally a metal solidification layer 22 with an inner contour formed by solidification of molten metal is formed in the central area of ​​the topmost metal powder thin layer in the molding groove 7; at this time, the inner contour edge 20 of the metal solidification layer 22 is within the inner contour enclosure range of the metal powder pre-filling bin 10 in a top view; at this time, there are a large number of metal sintered particles 35 on the inner contour edge 20 of the metal solidification layer 22, which are formed by the metal powder melting, gathering into droplets and then rapidly solidifying, and intersecting with the metal powder, such as Figure 6 As shown, the boundary of the contour line of the inner contour edge 20 of the newly formed metal solidification layer 22 is blurred and unclear, which easily causes a large number of irregular pits, protrusions and burrs to exist on the inner wall surface of the vertical through cavity 18 of the target molded part 22a formed in the end;

[0038] Step 4, control the originally vertical telescopic arm 5 to swing downward clockwise around the transverse steering gear shaft 28, and the telescopic part 5a of the telescopic arm 5 is adaptively extended, so that the carbide fine twist rope 19 is always in a taut state while swinging downward around the tip of the rotating cone head b 14, and is downwardly separated from the alloy wire constraint rod 16, as the telescopic arm 5 continues to swing downward clockwise around the transverse steering gear shaft 28, until the carbide fine twist rope 19 vertically contacts the inner contour edge 20 of the topmost metal solidification layer 22, at this time, the telescopic part 5a further applies a certain thrust to control the adaptive change of the transverse steering gear shaft 28, so that the carbide fine twist rope 19 maintains tension while the carbide fine twist rope 19 forms a local bend at the contact position with the inner contour edge 20 of the topmost metal solidification layer 22, and the local bending position of the carbide fine twist rope 19 is recorded as the local bending part 19a of the carbide fine twist rope. At this time, the local bending part 19a of the carbide fine twist rope contacts the inner contour edge 20 of the topmost metal solidification layer 22. The edge 20 forms a local push stress; at this time, the a motor 23 and the b motor 13 are controlled simultaneously, so that the tip of the a rotating cone head 6 and the tip of the b rotating cone head 14 rotate at the same speed and the same rotation direction, so that any cross section of the tightened carbide fine twist rope 19 rotates along its own center, and the local bending portion 19a of the carbide fine twist rope rolls the local area of ​​the inner contour edge 20 of the top metal solidification layer 22. Since the carbide fine twist rope 19 is twisted by a plurality of carbide wires, a plurality of ridge-like structures 64 are formed on the periphery of the cross section of the local bending portion 19a of the carbide fine twist rope, and the metal sintered particles 35 bonded to the local position of the inner contour edge 20 of the top metal solidification layer 22 are peeled off under the rolling of the local bending portion 19a of the carbide fine twist rope, and the local position of the inner contour edge 20 of the top metal solidification layer 22 is more dense and uniform under the rolling of the local bending portion 19a of the carbide fine twist rope, thereby eliminating the local surface stress;

[0039] Subsequently, in the subsequent process of this step, the thrust of the telescopic portion 5a of the telescopic arm 5 is always adaptively controlled to keep the tension of the carbide fine-twist rope 19 stable. At the same time, the disc drive motor 12 is controlled to drive the rotating disc 11 to rotate at least one circle along the axis, so that the local bent portion 19a of the carbide fine-twist rope rolls along the contour path of the inner contour edge 20 of the uppermost layer of metal solidification layer 22, so that the rolling local bent portion 19a of the carbide fine-twist rope rolls along the inner contour edge 20 of the uppermost layer of metal solidification layer 22. The contour path is rolled and scanned, so that all the bonded metal sintered particles 35 of the local bending portion 19a of the hard alloy fine twist rope along the inner contour edge 20 of the uppermost metal solidification layer 22 are peeled off under the rolling movement of the local bending portion 19a of the hard alloy fine twist rope, and the inner contour edge 20 of the uppermost metal solidification layer 22 is more dense and uniform under the rolling of the local bending portion 19a of the hard alloy fine twist rope, thereby eliminating the local surface stress and making the boundary of the contour line of the inner contour edge 20 of the newly formed metal solidification layer 22 clear and smooth;

[0040] Step 5: The telescopic arm 5 is swung counterclockwise upward around the transverse steering gear shaft 28 to restore the telescopic arm 5 to the vertical upward position in the initial state, and the carbide fine twist rope 19 is stretched across the lower side of the alloy wire restraint rod 16, and the upper section of the carbide fine twist rope 19 tends to be vertical; so that in a top-down perspective, the telescopic arm 5, the a-rotating cone head 6 and the carbide fine twist rope 19 are all within the enclosed range of the vertical through cavity 18 that is ultimately to be formed;

[0041] Step 6: Lay a new thin layer of metal powder in the forming tank 7;

[0042] Step 7, continuously repeating the process of "step 3" to "step 6" to stack several layers of metal solidification layers 22 from bottom to top until the target molded part 22a is completed; the outer periphery of the target molded part 22a forms an outer powder filling body 7a, and the inner periphery of the vertical through cavity 18 of the target molded part 22a forms an inner powder filling body 18a;

[0043] Since each layer of metal solidification layer 22 is rolled more densely and evenly by the inner contour edge 20 under the local bending portion 19a of the hard alloy fine twist rope, the local surface stress is eliminated, and the metal sintered particles 35 are peeled off, the boundary of the contour line of the inner contour edge 20 is clear and smooth; therefore, the inner wall surface of the vertical through cavity 18 of the final target molded part 22a is homogeneous, smooth, not easy to crack, and does not have a large number of irregular pits, protrusions and burrs.

[0044] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A layer-by-layer optimization system for the inner wall of a through-cavity formed by laser additive manufacturing, characterized by: The invention comprises a laser device (3) with a laser head (2) capable of XYZ movement and facing downward, a molding substrate (9) and a through-cavity inner contour layer-by-layer optimization device (51); the substrate (9) is provided with an enclosure wall (17) on its outer periphery, and a molding groove (7) is provided inside the enclosure wall (17); the laser device (3) melts a preset area of ​​a metal powder layer laid in the molding groove (7) and then solidifies the area, so that the preset area forms a metal solidification layer (22) with an inner contour, and the through-cavity inner contour optimization device (51) optimizes a clear inner contour along the inner contour edge (20) of the metal solidification layer (22).

2. The layer-by-layer optimization system for laser additive forming through-cavity inner wall according to claim 1, characterized in that: A downwardly extending sinking cylinder (15) is integrally provided in the center of the molding substrate (9), and a metal powder pre-filling bin (10) is located in the sinking cylinder (15); the metal powder pre-filling bin (10) is pre-filled with metal powder to form a pre-filling bin metal powder filling body (10a).

3. The layer-by-layer optimization system for laser additive forming through-cavity inner wall according to claim 2, characterized in that: The layer-by-layer optimization device (51) for the inner contour of the through-mold cavity comprises a rotating disk (11) coaxially arranged at the bottom end of a sinking cylinder (15).

4. The layer-by-layer optimization system for laser additive forming through-cavity inner wall according to claim 3, characterized in that: The through-cavity inner contour layer-by-layer optimization device (51) also includes an upwardly extending vertical rod (8) fixedly connected to the upper end of the rotating disc (11) coaxially, the vertical rod (8) upwardly coaxially passes through the metal powder pre-filling bin (10), and passes upwardly to the top end higher than the molding groove (7); lifters (1) are fixedly installed on both sides of the vertical rod (8), the upper end of the lifting rod (1a) of the lifter (1) is fixedly connected to a steering gear seat (27), the steering gear seat (27) is installed with a swing arm steering gear (4), the transverse steering gear shaft (28) of the swing arm steering gear (4) is vertically connected to a telescopic arm (5), the end of the telescopic part (5a) of the telescopic arm (5) is vertically fixedly installed with a motor (23), and the output end of the motor (23) is coaxially connected to a rotating cone head (6); A b motor (13) is installed on the lower side of the edge of the rotating disc (11), and a b rotating cone head (14) with a pointed tip facing upward is arranged on the upper side of the edge of the rotating disc (11), and the b motor (13) can drive the b rotating cone head (14) to rotate; The vertical rod (8) is hollowed out with an alloy wire passing slot (24) extending in the vertical direction, and a transverse alloy wire restraining rod (16) is fixedly arranged at the upper end of the alloy wire passing slot (24); It also includes a hard alloy fine twist rope (19), which obliquely passes through the alloy wire passing groove (24), and the upper and lower ends of the hard alloy fine twist rope (19) are respectively fixedly connected to the tip of the a rotating cone head (6) and the tip of the b rotating cone head (14).

5. The layer-by-layer optimization system for laser additive forming through-cavity inner wall according to claim 4, characterized in that: The axis of the a motor (23) is perpendicular to the axis of the transverse steering gear shaft (28).

6. The layer-by-layer optimization system for laser additive forming through-cavity inner wall according to claim 5, characterized in that: The cross-sectional outer diameter of the hard alloy fine twist rope (19) ranges from 1.5 mm to 2.5 mm.

7. The layer-by-layer optimization system for laser additive forming through-cavity inner wall according to claim 6, characterized in that: The hard alloy fine twist rope (19) is formed by twisting a plurality of hard alloy wires.

8. The optimization process of the layer-by-layer optimization system for laser additive forming through-cavity inner wall according to claim 7, characterized in that: Step 1: In the initial state, the telescopic arm (5) is vertically facing upward, and the hard alloy fine twist rope (19) is stretched across the lower side of the alloy wire restraining rod (16); Step 2: a thin layer of metal powder of a preset thickness is laid in the forming groove (7); Step 3, controlling the laser device (3) to form a metal solidification layer (22) having an inner contour formed by solidification of molten metal in the central area of ​​the uppermost metal powder thin layer in the forming groove (7); Step 4, control the originally vertical telescopic arm (5) to swing clockwise downward around the transverse steering gear shaft (28), and the telescopic part (5a) of the telescopic arm (5) is adaptively extended, so that the carbide fine twist rope (19) maintains tension while the carbide fine twist rope (19) forms a local bend at the contact position with the inner contour edge (20) of the uppermost metal solidification layer (22), and the local bending position of the carbide fine twist rope (19) is recorded as the local bending part (19a) of the carbide fine twist rope; at this time, the tip of the a rotating cone head (6) and the tip of the b rotating cone head (14) are simultaneously controlled to rotate at the same speed and the same rotation direction, so that any cross-section of the tightened carbide fine twist rope (19) at this time rotates along its own center, and the carbide fine twist rope (19) maintains tension and remains stable while the disk drive motor (12) is controlled to drive the rotating disk (11) to rotate at least one circle along the axis.

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