Electric arc fuse wire additive manufacturing method for complex curved surface structural member based on equal-arc-length slicing

Abstract

The invention discloses an arc fuse additive manufacturing method for a complex curved surface structural member based on equal-arc-length slices, and provides an equal-arc-length slice forming strategy for an annular structural member with the maximum inclination angle exceeding 45 degrees and the outer wall contour capable of being enveloped by an arc section. Extracting an outer wall contour envelope curve formed by fitting circular arc sections in the cross section of the center line of the part model, performing segmentation cutting with equal arc lengths along the outer wall envelope curve, constructing a radius line passing through a segmentation point and a circle center at each cutting point, and rotating the radius line around the center line of the part model for a circle to form a rotating curved surface, performing layered slicing on the part model by taking the curved surface as a segmentation curved surface to generate an additive manufacturing track; and the structural part is obtained through electric arc fuse wire additive manufacturing. According to the method, the forming stability and the material utilization rate of the complex parts are effectively improved, the production period is remarkably shortened, and the cost is reduced.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of metal additive manufacturing, and particularly relates to an arc wire additive manufacturing method based on equal-arc-length slicing for a complex curved structure, which is an annular structure with a maximum inclination angle exceeding 45° and an outer wall contour that can be enveloped by an arc segment, and has the advantage of rapid prototyping. BACKGROUND

[0002] The arc wire additive manufacturing technology forms metal droplets through arc high-temperature heating of welding wire and accumulates three-dimensional entity parts layer by layer. The arc wire additive manufacturing technology uses an arc heat source to heat and melt wire material, has the advantages of high deposition efficiency, shorter deposition period, and low production cost, and is suitable for additive prototyping of large complex structures in any spatial path.

[0003] Currently, the slicing methods for arc wire additive manufacturing processes mainly include three types. One is the traditional one-way equal-layer-thickness slicing method, which slices the part model along the building direction with equal thickness. This slicing method is simple and easy to apply, but when forming complex parts, it often needs to add support structures, and has the problems of step effect, low processing efficiency, large processing allowance, and high processing cost. The second is the one-way adaptive slicing method, which changes the layer thickness by considering the part shape along the building direction. This method improves the surface processing quality of the part, reduces the processing time, and improves the forming efficiency, but has high requirements for the shape of the part structure, and has certain problems in forming overhanging structures. The third is the multi-directional slicing method, which disassembles the part into multiple sub-parts, each of which has its own specific slicing direction. This method has less dependence on support structures and can realize the construction of complex parts, but the path planning is complex and easy to introduce cumulative errors. For annular structures with an inclination angle exceeding 45°, the above slicing methods are difficult to effectively adapt to the geometric characteristics of the inclined annular structure, and the molten pool is significantly affected by gravity during the forming process, which easily causes the molten pool to flow and collapse, seriously threatening the stability of the forming process and the geometric precision and surface quality of the final part.

[0004] The core of solving the problems of poor forming stability and molten pool collapse in the inclined annular structure arc fuse additive process is to overcome the adverse effects of gravity on the molten pool and realize the controllable, stable and precise accumulation of materials at any position in space. At present, the research results of inclined structure arc fuse additive stable forming are mainly divided into two categories. One is to add support auxiliary parts, such as the invention patent application with the publication number CN116673577A discloses an arc additive method suitable for inclined structure parts. The method guarantees the quality and forming process stability of the inclined surface by introducing support structure, but the support structure is difficult to completely remove and may be left in the formed parts. The other is to use magnetic force to balance the gravity of the molten pool, such as the invention patent application with the publication number CN118123183A discloses a support-free arc additive inclined structure method and device based on bidirectional magnetic force assistance. The technology can effectively guarantee the forming quality and precision of the inclined structure, but the device is relatively complex.

[0005] Therefore, for inclined annular structure parts, it is particularly urgent to propose an arc fuse additive manufacturing method without support auxiliary parts and magnetic assistance device, which is simple and convenient to operate. SUMMARY

[0006] The purpose of the application is to solve the problems of difficult path planning, uneven cladding layer and unstable process in the forming process of complex curved surfaces such as inclined annular structure. The application provides an arc fuse additive manufacturing method suitable for inclined annular structure parts. Through the equal arc length slicing strategy, the method has the advantages of high deposition efficiency, low manufacturing cost, stable forming process and near net shape.

[0007] Technical scheme: In order to achieve the above-mentioned purpose of the application, the application provides the following technical scheme:

[0008] An arc fuse additive manufacturing method for complex curved surface structure parts based on equal arc length slicing, which innovatively proposes an equal arc length slicing strategy: based on the three-dimensional model of the part, the outer wall envelope curve formed by the circular arc segment fitting is extracted in the center line section, the outer wall envelope curve is segmented and cut with equal arc length, the radius line is rotated around the part model center line 3 for one revolution to form a rotary surface 13, the part model is layered and sliced with the surface as the division surface, and the additive manufacturing track is generated. As shown in Figure 1 The specific steps include the following steps:

[0009] Step 1: For the three-dimensional digital model of the complex curved surface structure, in the cross section through the model center line, the outer wall profile envelope curve formed by the fitting of circular arc segments is extracted, and the arc length equal segmentation cutting is carried out along the extracted outer wall envelope curve. The equal division arc length size (L) is selected according to the actual electric arc wire additive process parameters. Since direct measurement and equal division arc length operation are difficult, the following formula is used to calculate the arc length (L) corresponding to the central angle (θ) size, and the equal division arc length is realized by equal division of the central angle:

[0010]

[0011] In the formula, θ is the central angle (unit: radian), L is the arc length (unit: millimeter), and r is the radius of the circular arc at the point (unit: millimeter).

[0012] At each segmentation point, the outer wall envelope curve method plane of the point is established, that is, the rotating surface passing through the segmentation point and the radius line of the center and perpendicular to the envelope curve, and the foot point is the segmentation point. The part model is sliced by taking the rotating surface as the segmentation plane, as shown in Figure 2 .

[0013] Step 2: In the cross section through the model center line, each layer of the slice is regarded as a rectangular cross section, and the height h of the center point of the rectangular cross section, the horizontal distance s of the center point to the model center line, and the included angle α (i.e. the inclination angle) between the short side direction of the rectangular cross section and the vertical direction are recorded. The inclination angle α directly determines the angle at which the machine tool workbench needs to be tilted to match the welding gun posture in the deposition process, as shown in Figure 3 . The recorded data h, s, α are input into the machine tool control system to generate the additive manufacturing trajectory. The additive manufacturing trajectory is shown in Figure 4 , so that the direction of the welding gun always strictly matches the tangent direction of the additive manufacturing trajectory, ensuring that the welding gun always points at the surface of the growing deposition layer at the best angle.

[0014] Step 3: Two layers of metal cladding layers are deposited on the substrate as the base, which helps to avoid the welding gun from colliding with the substrate during subsequent deposition, and at the same time fills part of the bottom of the structure.

[0015] Step 4: The electric arc additive manufacturing machine tool with five-axis linkage function is used to additively form the part. According to the additive trajectory path generated in step 1, the numerical control system of the machine tool coordinates the movement of the welding gun and the inclination and rotation movement of the workbench in real time, ensuring that at each deposition point, the direction of the welding gun is accurately along the tangent direction of the path, and the distance between the welding gun and the deposition layer surface is constant, and the wire length of the welding wire is stable. In this way, the metal material is stacked layer by layer according to the preset path, until the additive manufacturing of the entire structure is completed.

[0016] Further, the complex curved surface structure is an inclined annular structure, the maximum inclination angle is more than 45°, and the outer wall contour can be enveloped by an arc segment, the number of the arc segments is selected according to the shape of the inclined annular structure, and the inclined annular structure can be enveloped by one arc or a plurality of continuous arcs.

[0017] Further, the arc length size (L) of the equal division is equal to the single-layer structure height deposited by the actual electric arc wire additive process parameters.

[0018] Further, the actual electric arc wire additive process parameters include a wire feeding speed V w , and a feeding speed V f .

[0019] Advantages:

[0020] (1) The application provides an electric arc additive forming method for a complex curved surface structure based on an equal-arc-length slicing strategy, and realizes stable electric arc additive forming of the complex curved surface structure. The equal-arc-length slicing strategy makes the deposition height of each layer more uniform, and reduces the heat accumulation difference between layers. The welding gun always moves along the tangent direction of the path, the distance between the welding gun and the deposition layer surface is kept constant, the wire length is stable, and the workbench is dynamically adjusted to ensure that the welding gun and the inclined annular structure have the best forming angle and posture in the additive process, thereby avoiding the molten pool flow and collapse caused by unstable wire length due to fixed layer height in the traditional equal-height slicing, and significantly improving the one-time forming success rate.

[0021] (2) The equal-arc-length slicing strategy significantly reduces the waste of raw materials, improves the accumulation efficiency, and reduces the cost. The equal-arc-length slicing makes the deposition path length of each layer uniform, and the constant arc length is segmented to cooperate with the tangential control of the welding gun, thereby significantly reducing the demand for multi-pass overlapping. At the same time, the equal-arc-length slicing strategy improves the stability of the molten pool and reduces the material loss caused by the flow or spatter of the molten pool.

[0022] (3) The part formed by using the equal-arc-length slicing strategy has more excellent part surface quality, and realizes "near-net forming". The equal-arc-length slicing ensures that the deposition path length of each layer is basically consistent, so that the heat input is more uniform, and defects such as metal spatter and droplet spheroidization caused by local overheating or overcooling are reduced. The surface of the inclined annular structure formed by using the equal-arc-length slicing is smooth and flat, the workload and time of subsequent polishing and polishing and other finishing processes are reduced, the overall manufacturing efficiency is further improved, and the product delivery cycle is shortened. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 is a flow chart of the electric arc wire additive manufacturing of the inclined annular structure based on the equal-arc-length slicing;

[0024] Figure 2 is a principle diagram of the equal-arc-length slicing.

[0025] Figure 3 is a schematic diagram of key parameters under the equal-arc-length slicing strategy of the present application;

[0026] Figure 4 is an additive trajectory diagram of the inclined annular structure of the present application;

[0027] Figure 5 is a schematic diagram of the relationship between the closed impeller structure (left) and the inclined annular structure (right) in Example 1;

[0028] Figure 6 is a curve diagram of the inclination angle a and the distance s to the center line as a function of the slice height h of each layer in Example 1;

[0029] Figure 7 is a superimposed contrast diagram of the actual cross-sectional profile line (solid line) of the shaped inclined annular structure after being cut along the center line and the profile line (dashed line) of the theoretical model in the example.

[0030] Names of various marks in the figure: 1-outer wall envelope curve, 2-radius line connecting the division point and the center of the circle, 3-center line of the part model, 4-arc length L, 5-central angle θ, 6-rectangular cross section, 7-height h of the center point of the rectangular cross section, 8-distance s of the center point of the rectangular cross section to the center line of the part model, 9-inclination angle a, 10-welding gun, 11-division point, 12-center of the circle, 13-rotating surface. DETAILED DESCRIPTION

[0031] In order for those skilled in the art to better understand the technical solutions in the patent application, the technical solutions in the present application will be described below by applying examples in combination with the drawings in the present application. The described embodiments are only one of the embodiments in the present application, not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor should be within the scope of protection of the present application.

[0032] An electric arc additive manufacturing method for a complex curved surface structure based on equal-arc-length slicing, based on the equal-arc-length slicing forming strategy, is suitable for rapid forming of annular structure with a maximum inclination angle exceeding 45° and an outer wall profile that can be enveloped by a circular arc segment.

[0033] The adopted equal arc length slicing strategy is: firstly, a three-dimensional model of the annular structure part is constructed by means of a three-dimensional modeling software; then, based on the three-dimensional model of the part, an outer wall profile envelope curve formed by a circular arc segment fitting is extracted in the central line cross section, arc length equal segmentation cutting is performed along the extracted outer wall envelope curve, and an outer wall envelope curve method plane of each segmentation point is established, that is, a rotation surface with the vertical foot being the segmentation point is established through the radius line of the segmentation point and the center and perpendicular to the envelope curve, the part model is sliced by taking the rotation surface as the segmentation plane, and an additive manufacturing track deposition inclined annular structure part is generated, which can effectively improve the surface forming quality and material utilization rate of the arc additive manufacturing of the inclined annular structure, significantly shorten the production cycle and reduce the cost.

[0034] The application will be further described in detail below with reference to the examples.

[0035] Example 1

[0036] This example takes the inclined annular structure commonly present in the inner and outer wall parts of a closed impeller component as an example, as shown in Figure 5 An equal arc length slicing-based arc wire additive manufacturing method of an inclined annular structure is provided, and the steps are as follows:

[0037] Step 1: Gefertec Arc405 five-axis arc wire additive system is selected, which is composed of an additive machine tool and an Advanced 4000 type welding power supply of Fronius company. The machine tool is equipped with a Siemens five-axis linkage numerical control system and a laser pyrometer with a temperature measurement range of 0-1500℃ for accurate control of interlayer temperature.

[0038] Step 2: based on the three-dimensional model of the inclined annular structure part in Figure 5 , an outer wall profile envelope curve 1 formed by a circular arc segment fitting is extracted in the central line cross section, arc length equal segmentation cutting is performed along the extracted outer wall envelope curve, and the equal arc length L is set to 2.5mm according to the selected process parameter single layer structure height. The outer wall of the inclined annular structure is composed of two circular arcs, the radius r1 of the lower circular arc is 75mm, and the corresponding central angle is 22.05°; the radius r2 of the upper circular arc is 100mm, and the corresponding central angle is 11.48°, the equal division central angle θ size is calculated according to formula (1), and the equal division arc length is realized by equal division central angle:

[0039]

[0040] In the formula, θ is the equal division central angle, L is the arc length, and r is the radius of the circular arc;

[0041] The equal division central angle of the lower circular arc is 1.68°, and the equal division central angle corresponding to the radius 100mm of the upper circular arc segment is 1.26°.

[0042] At each split point, a radius line is constructed through the split point and the center of the circle. The radius line is rotated around the center line of the part model to form a rotating surface. The surface is used as a split surface to slice the part model.

[0043] Step 3: In the cross section through the model center line, each layer slice is regarded as a rectangular cross section. The height h and the distance s of the center point of each rectangular cross section to the center line of the part model are recorded. The angle a between the short side direction and the vertical direction of each rectangular cross section is recorded. Figure 6 The trend of parameters s and a with h is shown. The recorded data h, s, a are input into the machine tool control system to generate the additive manufacturing trajectory. The direction of the welding torch in the trajectory data is always consistent with the tangent direction of the point.

[0044] Step 4: The welding wire used in the inclined annular structure additive forming is GH4169 high-temperature alloy solid welding wire with a diameter of 1.2 mm. The chemical composition meets the AMS 5662 standard. The dry elongation of the welding wire is 12-15 mm. The welding wire needs to be straightened before additive manufacturing. The error in the xy direction after straightening is ≤2 mm. The additive manufacturing substrate is a Q235 steel substrate with a size of 200 mm x 100 mm x 10 mm. To prevent the influence of the oxide film and oil stains on the surface of the workpiece substrate on the arc additive manufacturing process, the upper surface of the substrate is first polished with sandpaper, and then the polished surface is wiped with ethanol solution to remove rust and oil stains and increase the surface wettability. The experimental platform is built. The substrate after surface treatment is fixed on the workbench with a clamp. The GH4169 high-temperature alloy welding wire is sent to the welding torch through the straightener through the wire feeder. The protective gas is a four-component protective gas mainly containing argon and helium, with a small amount of carbon dioxide and oxygen added to stabilize the arc and improve the wettability. The gas flow is 15 L / min.

[0045] Step 5: Select the wire feeding speed of 5 m / min, the feeding speed of 400 mm / min (corresponding to the linear energy density of 375.6 J / mm), and the reciprocating deposition path to perform arc welding wire additive manufacturing of the inclined annular structure. Two layers of GH4169 metal cladding layers are deposited on the additive manufacturing substrate as the base by using two overlapping deposition paths. The interlayer temperature of each layer is controlled at 100°C. According to the additive trajectory generated in step 3, the additive manufacturing is performed layer by layer upwards until the arc welding wire additive manufacturing of the entire inclined annular structure is completed. Under this strategy, only a single deposition path is required without the need for multiple overlapping. The experimental results show that compared with the traditional one-way equal-thickness slicing deposition method (deposition time is 4072.4 s), the preparation time of the inclined annular structure under this strategy is significantly shortened (deposition time is 2214.4 s), the material deposition efficiency is improved by about 45.62%, the raw material utilization rate is significantly improved, and the manufacturing cost is greatly reduced.

[0046] Step 6: The formed inclined ring structure is scanned by a laser binocular vision scanner (model TrackScan series P550), and the scanned reverse model is compared with the theoretical model, Figure 7 By a sectional view, the actual sectional profile line of the formed part (solid line) is directly superimposed and compared with the profile line of the theoretical model (dashed line), the actual model can completely envelop the theoretical model, and the two have high consistency, and the forming is complete.

[0047] The formed part of the embodiment 1 meets the geometric size requirements of the inclined ring structure, improves the material utilization, shortens the manufacturing cycle, and reduces the finishing cost compared with the traditional casting process.

[0048] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for additive manufacturing of arc fuses for complex curved surface structural parts based on equal arc length slices, characterized in that: Here are the steps: Step 1: Using 3D modeling software, construct a 3D model of a complex curved surface structural part, extract an outer wall contour envelope curve (1) formed by fitting arc segments within the centerline section of the 3D model, and perform segmented cutting with equal arc lengths along the outer wall envelope curve (1); Step 2: At each cutting point (11), a radius line (2) passing through the dividing point and the center of the circle is constructed, and the radius line is rotated around the center line (3) of the part model to form a rotating surface (13). The part model is sliced ​​using this surface as a dividing surface to generate an additive manufacturing trajectory; Step 3: Pre-deposit two layers of metal cladding on the substrate as a base to avoid interference between the welding gun and the substrate during the subsequent additive process. At the same time, fill the bottom area of ​​the complex curved surface structural parts to facilitate high-precision contour forming. Step 4. According to the additive trajectory path generated in Step 2, an arc additive manufacturing machine with a five-axis linkage function is used to additively form the part. The CNC system of the machine coordinates the movement of the welding gun and the tilting and rotation of the worktable in real time to ensure that at each deposition point, the welding gun direction is along the tangent direction of the path, the distance between the welding gun and the surface of the deposition layer is constant, and the welding wire length remains stable. In this way, the metal material is deposited layer by layer according to the preset path until the additive manufacturing of the entire inclined annular structure is completed.

2. The method for additive manufacturing of arc fuses for complex curved surface structural parts based on equal arc length slices according to claim 1, characterized in that: The complex curved surface structural part is an inclined annular structural part with a maximum inclination angle exceeding 45°, and the outer wall contour can be enclosed by arc segments. The number of arc segments is determined according to the shape of the inclined annular structural part, and is an envelope of one or more continuous arc segments.

3. The method for additively manufacturing arc fuses for complex curved surface structural parts based on equal arc length slices according to claim 1, characterized in that: In step 1, the arc length L corresponding to the central angle θ is calculated using formula (1), and the arc length is divided equally by dividing the central angle: Where θ is the central angle of the circle, in radians; L is the arc length, in millimeters; and r is the radius of the arc at that point, in millimeters.

4. The method for additively manufacturing arc fuses for complex curved surface structural parts based on equal arc length slices according to claim 1, characterized in that: In step 4, the height of the single-layer structure of the actual arc fuse additive deposition is equal to the arc length L divided equally.

5. The method for additively manufacturing arc fuses for complex curved surface structural parts based on equal arc length slices according to claim 1, characterized in that: The specific implementation process of step 2 is as follows: within the section passing through the centerline of the 3D model, each slice is regarded as a rectangular section. The height h of the center point of the rectangular section, the horizontal distance s from the center point to the centerline of the model, and the angle α between the short side of the rectangular section and the vertical direction are recorded. This angle is the inclination angle, which determines the angle at which the machine tool worktable needs to be tilted to match the welding gun posture during the deposition process; the recorded data h, s, α are input into the machine tool control system to generate the additive manufacturing trajectory.

6. The method for additively manufacturing arc fuses for complex curved surface structural parts based on equal arc length slices according to claim 1, characterized in that: In step 3, the material of the metal cladding layer as the base is the same as the material of the welding wire.

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