CN113695837A - Turtle shell bionic curved surface block-shaped net-shaped bimetal repair structure and preparation method thereof - Google Patents
Turtle shell bionic curved surface block-shaped net-shaped bimetal repair structure and preparation method thereof Download PDFInfo
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- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23P—METAL-WORKING NOT OTHERWISE PROVIDED FOR; COMBINED OPERATIONS; UNIVERSAL MACHINE TOOLS
- B23P6/00—Restoring or reconditioning objects
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- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K9/00—Arc welding or cutting
- B23K9/04—Welding for other purposes than joining, e.g. built-up welding
- B23K9/044—Built-up welding on three-dimensional surfaces
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- B33—ADDITIVE MANUFACTURING TECHNOLOGY
- B33Y—ADDITIVE MANUFACTURING, i.e. MANUFACTURING OF THREE-DIMENSIONAL [3-D] OBJECTS BY ADDITIVE DEPOSITION, ADDITIVE AGGLOMERATION OR ADDITIVE LAYERING, e.g. BY 3-D PRINTING, STEREOLITHOGRAPHY OR SELECTIVE LASER SINTERING
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Abstract
A bionic curved surface block-shaped net-shaped bimetal repairing structure of a tortoise shell comprises: the shape-following additive layer is formed by splicing and combining a plurality of blocks, each block comprises an internal hard filling block and a boundary gap soft filling frame, each block boundary gap soft filling frame is a frame with the inward offset width d of the boundary of each block, and the internal hard filling block is arranged in the middle of each boundary gap soft filling frame; the preparation method comprises the following steps: step 1, obtaining a curved surface to be repaired; step 2, discrete blocks of the curved surface to be repaired are divided; step 3, planning a curved surface shape-following additive track; step 4, shape-following additive repair; step 5, performing shape-following material increase on the areas in the blocks; step 6, filling the blocking gap area with a shape-following additive; and 7, performing heat treatment and machining. The design not only can realize the tough coupling and effectively prolong the service life of parts, but also can adapt to the differentiated performance requirements of different areas, and has wide application range.
Description
Technical Field
The invention relates to a turtle shell bionic curved surface block net-shaped bimetal repairing structure and a preparation method thereof, which are particularly suitable for improving the high temperature resistance, impact resistance and friction resistance of a part repairing part.
Background
A large number of key high-performance bearing components in the fields of automobiles, aerospace, ships, energy sources and the like are forged and formed (such as automobile front shafts, aircraft landing gears, large crankshafts of marine engines, main shafts of wind power generators and the like). The forging die is in direct contact with a high-temperature forging stock (900-1200 ℃) in the service process, bears the alternating high-temperature, heavy-load and severe friction action of multiple circulation passes, is very easy to generate profile abrasion, cracks, plastic deformation and fracture failure, is short in service life, usually only has 3000-5000 parts, is low in service life of an aviation high-strength steel and titanium alloy forging die, even only has 10-50 parts, and seriously restricts the reduction of the production cost of enterprise forgings and the high-efficiency production and manufacturing of key components in the national important field.
The forging die has the advantages of complex manufacturing process, long production period, high material consumption and high value, and in order to reduce the production cost, the failed forging die needs to be repaired and remanufactured for multiple times so as to prolong the service life of the failed forging die. At present, a failed forging die is mainly repaired by a manual or robot arc surfacing process, a failed layer of a die surface of the forging die is cleaned in a machining or carbon arc gouging mode, and then a repair material is filled in the arc surfacing mode to restore the size, the shape and the performance of the forging die. According to the loaded characteristics of a forging die cavity, the existing repairing method forms a gradient performance structure by sequentially adopting various materials such as a bottom layer (HRC 34-42), a transition layer (HRC 42-48) and a cover surface layer (HRC 55) on a forging die failure surface along the depth direction, and improves the wear resistance of the forging die surface repairing layer and the bonding strength with a substrate to a certain extent. However, the die profile is subjected to high temperature, impact load and severe friction, increasing hardness may increase wear resistance and deformation resistance to some extent, but material toughness may decrease, leading to microcracks forming and gradual expansion of the profile under load, leading to early failure of the die. Therefore, it is necessary to improve the comprehensive mechanical properties of the forging die surface, such as strength and toughness, so as to improve the comprehensive service performance of the forging die, such as wear resistance, deformation resistance and crack resistance.
The organism structure of organisms in nature has evolved and evolved for hundreds of millions of years, and functional structures meeting environmental requirements can be obtained, so that a large number of examples exist, wherein the examples simultaneously have high hardness and high toughness. For example, the tortoise shell is composed of 13 block structures, the blocks are high-hardness skeleton shield pieces, soft collagen is arranged between the bone seams of the adjacent blocks, and the block structures are organically combined, so that the tortoise shell is 'rigid and flexible', has high strength and certain deformability, is beneficial to dissipating external mechanical kinetic energy, prevents the tortoise shell from forming microcracks when being subjected to impact loads such as collision, occlusion and the like, and quickly absorbs energy when the cracks pass through soft gaps from the hard shield pieces, so that the expansion of the cracks is limited, and the overall safety of the tortoise shell is ensured. In addition, the 'rotating-mud' assembly structure of the shell pearl layer and the reinforcing rib structures of the leaves and the dragonfly wings are all bionic templates which are in tough coupling in nature, and the tough coupling of the body structure is realized through a heterogeneous material block structure, so that the requirements on comprehensive mechanical properties of strength and toughness are met.
The molded surfaces of parts are strengthened to a certain degree at home and abroad by adopting a bionic principle, for example, the laser melting strengthening (local alloying) provided by the laser phase change strengthening method and the bionic camshaft (ZL 201710309875.3) adopting the method to prepare a hard phase in Chinese invention patents, the laser melting strengthening (local phase change strengthening) provided by the local laser melting and injecting bionic strengthening method and the equipment (ZL201310436473.1) on the surface of the water turbine blade; firstly, machining a certain hole, a groove and the like on a molded surface, melting and filling the material in a laser, plasma or electric arc mode and the like to realize a heterogeneous composite multi-material toughness structure. However, the heterostructure obtained by the methods has shallow depth, single heterostructure type, limited strengthening degree, low efficiency and small improvement on the toughness comprehensive mechanical property of the forging die profile.
Disclosure of Invention
The invention aims to solve the problems of poor high temperature resistance, impact resistance and friction resistance of a part repairing part in the prior art, and provides a turtle shell bionic curved surface block net-shaped bimetal repairing structure for improving the high temperature resistance, impact resistance and friction resistance of the part repairing part and a preparation method thereof.
In order to achieve the above purpose, the technical solution of the invention is as follows:
the bionic curved surface block-shaped net-shaped bimetal repairing structure of the tortoise shell comprises: shape-following additive layer, shape-following additive layer is formed by a plurality of piecemeal concatenation combinations, the piecemeal includes inside stereoplasm filled block and the soft filled frame in boundary gap, the soft filled frame in block boundary gap is the frame of the border of piecemeal inwards-biased width d, the soft filled frame middle part in boundary gap is inside stereoplasm filled block.
The blocks are polygonal plane or curved surface structures with the thickness of h.
At least two layers of the conformal additive layers are attached to form a net-shaped bimetal repairing structure, and the single-layer thickness h of the conformal additive layers is 2.0-4.0 mm.
The preparation method of the partitioned net-shaped bimetallic repair structure based on the turtle shell bionic curved surface comprises the following steps:
carrying out offset layering on the obtained three-dimensional digital model of the profile of the defect area: carrying out curved surface bias inwards on the basis of the outermost curved surface of the profile defect area of the part to obtain a multi-layer biased curved surface set
Wherein the offset distance is the single-layer thickness h of the conformal additive layer, and the number of offset layers NL＝H/h；
step 3, planning a curved surface shape-following additive track: planning arc material increase forming curved surface block shape-following material increase tracks distributed along the curved surface profile shape-following according to the geometric structure characteristics of each curved surface block, so that the curved surface block shape-following material increase tracks uniformly cover each block; planning arc additive filling tracks distributed along the block boundaries according to the block boundary gap geometrical characteristics;
and 4, starting from the curved surface at the bottommost layer, performing shape-following additive repair layer by layer from the top to the outside: the single-layer curved surface additive repairing method comprises the following steps: firstly, performing step 5, performing shape-following material increase on the areas in the blocks, then performing step 6, performing shape-following electric arc material increase filling on the block gap areas, and performing material increase repair on the next layer after the material increase repair of the whole layer of the curved surface is completed until the repair of all the material increase curved surface layers is completed;
step 5, carrying out shape-following material increase on the areas in the blocks: selecting a welding material with hardness, strength and wear resistance, and forming hard material blocks on the curved surface by shape-following material increase according to the curved surface block shape-following material increase track planned in the step 3, so that the material increase gradually covers each block until all blocks of the layer are subjected to material increase;
step 6, block gap area shape-following additive filling: and (3) selecting a welding material with toughness and plasticity, filling the block gaps with a soft material gap according to the shape-following additive filling track of the curved surface block gaps planned in the step (3), and gradually filling the boundary gaps of the blocks until the gaps of the layer are completely filled.
The preparation method also comprises the following steps of 7, heat treatment and machining: when all the repairing of the additive curved surface layers in the step 4 is finished, tempering and stress relieving heat treatment is carried out on the part subjected to additive repairing: controlling the tempering temperature at 550 ℃, preserving heat for 8 hours, cooling to the room temperature of 25 ℃ along with the furnace, preserving heat for 8 hours at 550 ℃, tempering, cooling to the room temperature of 25 ℃ along with the furnace, and finishing tempering;
and then, designing a geometric model of the tempered part according to the profile, machining the repaired profile to obtain an accurate working profile, and polishing to finish repairing the part.
In the step 2, the blocks of the complex curved surface realize the automatic division of the curved surface through a clustering algorithm to obtain a plurality of curved surface blocks Si,j(i∈[1,2,…NL],j∈[1,2,…MP])，MPThe number of blocks for a curved surface; firstly, dispersing a geometric curved surface into a curved surface point cloud, and determining a coefficient delta (delta belongs to [0, 1 ] in a subtraction clustering algorithm by modifying]) Determining the number of partitions MPDividing the curved surface point cloud into M by fuzzy C-means clustering algorithmPPartitioning, namely obtaining point cloud boundaries of all partitions through an alpha-shape algorithm to obtain a plurality of polygon partitions;
the smaller the numerical value of the determination coefficient delta is, the more the number of the blocks is, the larger the area ratio of the boundary gap soft filling frame in the blocks is, the larger the proportion of the soft material in the conformal additive layer is, and the stronger the toughness of the conformal additive layer is; on the contrary, the larger the numerical value of the determination coefficient delta is, the smaller the number of the blocks is, the larger the area proportion of the internal hard filling blocks in the blocks is, the larger the proportion of the hard material in the conformal additive layer is, and the larger the hardness of the conformal additive layer is; the size of the block is adjusted by adjusting the value of the determination coefficient delta, so that the proportion adjustment of hard and soft materials is realized, and finally, the comprehensive mechanical properties of wear resistance and crack resistance of the material are adjusted.
In step 3, the track planning in the blocks is as follows: the tracks in the blocks are generated by adopting an equal residual height method and an equidistant surface offset method, the distance between adjacent tracks needs to be ensured to meet the requirement of the lapping distance of the electric arc additive welding bead, each area needs to be uniformly covered, and no track overlap or gap exists; taking the central contour line of the block as a base line, taking 50% of the width W of the weld bead as an offset distance, gradually covering the block by a curve-on-surface equal-residual-height offset algorithm, and obtaining a plurality of curve tracks { Path } covering the whole block1,Path2,Path3,…PathKAnd K is the number of tracks, the tracks in each block on the curved surface are planned in sequence, and the gap width d is equal to 50-80% of the weld bead width W.
In the step 5, the welding material with hardness, strength and wear resistance needs to satisfy the following conditions: the hardness at normal temperature meets HRC 55-60, and the hardness at 400-700 ℃ meets HRC 40-45;
in the step 6, the welding material with toughness and plasticity needs to meet the following conditions: the hardness at normal temperature is HRC 35-40, the hardness at 400-700 ℃ is HRC 25-30, and the yield strength sigma issMore than 600MPa, elongation delta more than 17 percent and impact energy Akv>35J。
In the step 5, RMD650, GORE 3752-FCG or Eureka 750 welding wire is adopted;
RMD535, GORE 3235-FCG or Eureka 735 welding wire is used in step 6.
Compared with the prior art, the invention has the beneficial effects that:
1. according to the turtle shell bionic curved surface block-mesh-shaped bimetallic repair structure, a curved surface of a part to be repaired is divided into a plurality of blocks, and gaps with certain widths are arranged at the edges of the blocks; the high-strength hard welding material is filled in the blocking area along with the shape additive, and the high-toughness plastic welding material is filled in the gap area to form a blocking net soft-hard combined bionic structure similar to a tortoise shell, so that the high-strength coupling of the repairing molded surface is realized, the strength and the hardness are ensured, the toughness is improved, and the high wear resistance, the deformation resistance and the crack resistance of the molded surface are realized; compared with the existing profile homogeneous material, the composite structure can improve the toughness of the profile while ensuring the sufficient strength, hardness, wear resistance and deformation resistance of the profile; the soft material in the block gap can absorb impact energy, so that the tip of the crack is passivated or deflected to limit further expansion, thereby ensuring the strong and tough coupling of the whole part profile, improving the comprehensive mechanical properties of wear resistance, deformation resistance and crack resistance, and prolonging the service life of the part. Therefore, the design can realize the tough coupling and effectively prolong the service life of the part.
2. According to the preparation method of the tortoise shell bionic curved surface blocking net-shaped double-metal repair structure, a region to be repaired is modeled, the modeling is layered firstly, then blocking is carried out, and finally trajectory planning is carried out; because the posture change of the welding gun in each block of the curved surface is small, the welding bead is uniform in shape, and the surface appearance and quality of the curved surface conformal additive welding layer are optimized. Therefore, the repair scheme of the design is clear, and the surface appearance and quality of the curved surface shape-following additive welding layer are optimized.
3. According to the preparation method of the turtle shell bionic curved surface block-mesh bimetallic repair structure, the sizes of curved surface blocks and block gaps can be adjusted according to the distribution of temperatures and stress fields in different regions of a molded surface and the requirements on the structural performance of materials, so that the distribution proportion of hard materials and soft materials is adjusted, the hardness-toughness change of the block-mesh composite structure is realized, and the requirements on the differential performance of different regions are met. Therefore, the design can adapt to different regional differentiation performance requirements, and the application range is wide.
4. According to the preparation method of the turtle shell bionic curved surface block-shaped net-shaped bimetal repair structure, the repaired part is subjected to heat treatment, and through two times of high-temperature tempering heat treatment, on one hand, welding stress generated in an electric arc additive forming process is eliminated, on the other hand, stress caused by difference of thermal expansion coefficients of different materials in a block area and a gap is eliminated, the toughness of the repair structure is improved, and the fatigue performance is improved. Therefore, the design can improve the residual stress state of the additive layer and obtain the tough-coupled blocked net-shaped bimetal repair structure.
Drawings
Fig. 1 is a schematic structural view of the present invention.
FIG. 2 is a schematic view of a repair part of the present invention.
Fig. 3 is a schematic of the trajectory planning for a single conformal additive layer of the present invention.
In the figure: the flexible material-filled block comprises a conformal additive layer 1, blocks 2, an internal hard filling block 21 and a boundary gap soft filling frame 22.
Detailed Description
The present invention will be described in further detail with reference to the following description and embodiments in conjunction with the accompanying drawings.
Referring to fig. 1 to 3, the bionic curved surface block-shaped net-shaped bimetal repairing structure of the tortoise shell comprises: shape-following additive layer 1, shape-following additive layer 1 is formed by the concatenation combination of a plurality of piecemeals 2, piecemeal 2 includes inside stereoplasm filled block 21 and the soft filled frame 22 in boundary gap, the soft filled frame 22 in boundary gap of piecemeal is the frame of the interior offset width d in the boundary of piecemeal 2, the soft filled frame 22 middle part in boundary gap is inside stereoplasm filled block 21.
The block 2 is a polygonal plane or curved surface structure with the thickness of h.
At least two layers of the conformal additive layer 1 are attached to form a net-shaped bimetal repairing structure, and the single-layer thickness h of the conformal additive layer 1 is 2.0-4.0 mm.
The preparation method of the partitioned net-shaped bimetallic repair structure based on the turtle shell bionic curved surface comprises the following steps:
carrying out offset layering on the obtained three-dimensional digital model of the profile of the defect area: carrying out curved surface bias inwards on the basis of the outermost curved surface of the profile defect area of the part to obtain a multi-layer biased curved surface set
Wherein the offset distance is the single-layer thickness h of the conformal additive layer 1, and the number of offset layers NL＝H/h；
step 3, planning a curved surface shape-following additive track: planning arc material increase forming curved surface block shape-following material increase tracks distributed along the curved surface profile shape-following according to the geometric structure characteristics of each curved surface block, so that the curved surface block shape-following material increase tracks uniformly cover each block; planning arc additive filling tracks distributed along the block boundaries according to the block boundary gap geometrical characteristics;
and 4, starting from the curved surface at the bottommost layer, performing shape-following additive repair layer by layer from the top to the outside: the single-layer curved surface additive repairing method comprises the following steps: firstly, performing step 5, performing shape-following material increase on the areas in the blocks, then performing step 6, performing shape-following electric arc material increase filling on the block gap areas, and performing material increase repair on the next layer after the material increase repair of the whole layer of the curved surface is completed until the repair of all the material increase curved surface layers is completed;
step 5, carrying out shape-following material increase on the areas in the blocks: selecting a welding material with hardness, strength and wear resistance, and forming hard material blocks on the curved surface by shape-following material increase according to the curved surface block shape-following material increase track planned in the step 3, so that the material increase gradually covers each block until all blocks of the layer are subjected to material increase;
step 6, block gap area shape-following additive filling: and (3) selecting a welding material with toughness and plasticity, filling the block gaps with a soft material gap according to the shape-following additive filling track of the curved surface block gaps planned in the step (3), and gradually filling the boundary gaps of the blocks until the gaps of the layer are completely filled.
The preparation method also comprises the following steps of 7, heat treatment and machining: when all the repairing of the additive curved surface layers in the step 4 is finished, tempering and stress relieving heat treatment is carried out on the part subjected to additive repairing: controlling the tempering temperature at 550 ℃, preserving heat for 8 hours, cooling to the room temperature of 25 ℃ along with the furnace, preserving heat for 8 hours at 550 ℃, tempering, cooling to the room temperature of 25 ℃ along with the furnace, and finishing tempering;
and then, designing a geometric model of the tempered part according to the profile, machining the repaired profile to obtain an accurate working profile, and polishing to finish repairing the part.
In the step 2, the blocks of the complex curved surface realize the automatic division of the curved surface through a clustering algorithm to obtain a plurality of curved surface blocks Si,j(i∈[1,2,…NL],j∈[1,2,…MP])，MPthe number of blocks for a curved surface; firstly, dispersing a geometric curved surface into a curved surface point cloud, and determining a coefficient delta (delta belongs to [0, 1 ] in a subtraction clustering algorithm by modifying]) Determining the number of partitions MPDividing the curved surface point cloud into M by fuzzy C-means clustering algorithmPPartitioning, namely obtaining point cloud boundaries of all partitions through an alpha-shape algorithm to obtain a plurality of polygon partitions 2;
the smaller the value of the determination coefficient delta is, the more the number of the blocks is, the larger the area ratio of the boundary gap soft filling frame 22 in the block 2 is, the larger the proportion of the soft material in the conformal additive layer 1 is, and the stronger the toughness of the conformal additive layer 1 is; on the contrary, the larger the value of the determination coefficient δ is, the smaller the number of the blocks is, the larger the area ratio of the internal hard filling blocks 21 in the blocks 2 is, the larger the ratio of the hard materials in the conformal additive layer 1 is, and the larger the hardness of the conformal additive layer 1 is; the size of the block is adjusted by adjusting the value of the determination coefficient delta, so that the proportion adjustment of hard and soft materials is realized, and finally, the comprehensive mechanical properties of wear resistance and crack resistance of the material are adjusted.
In step 3, the track planning in the blocks is as follows: the tracks in the blocks are generated by adopting an equal residual height method and an equidistant surface offset method, the distance between adjacent tracks needs to be ensured to meet the requirement of the lapping distance of the electric arc additive welding bead, each area needs to be uniformly covered, and no track overlap or gap exists; taking the central contour line of the block 2 as a base line, taking 50% of the width W of the weld bead as an offset distance, and gradually covering the block by a curve-on-curved-surface equal-residual-height offset algorithmBlocking to obtain multiple curve tracks { Path } covering the whole block1,Path2,Path3,…PathKAnd K is the number of tracks, the tracks in each block on the curved surface are planned in sequence, and the gap width d is equal to 50-80% of the weld bead width W.
In the step 5, the welding material with hardness, strength and wear resistance needs to satisfy the following conditions: the hardness at normal temperature meets HRC 55-60, and the hardness at 400-700 ℃ meets HRC 40-45;
in the step 6, the welding material with toughness and plasticity needs to meet the following conditions: the hardness at normal temperature is HRC 35-40, the hardness at 400-700 ℃ is HRC 25-30, and the yield strength sigma issMore than 600MPa, elongation delta more than 17 percent and impact energy Akv>35J。
In the step 5, RMD650, GORE 3752-FCG or Eureka 750 welding wire is adopted;
RMD535, GORE 3235-FCG or Eureka 735 welding wire is used in step 6.
The principle of the invention is illustrated as follows:
the design can be used for repairing and remanufacturing invalid hot forging dies in the fields of automobiles, aerospace, ships, energy sources and the like, and can also be used for reinforcing profiles of newly manufactured forging dies and curved surface parts, namely, after the manufacture is finished, a plurality of layers of curved surface block reticular bimetallic turtle shell bionic structures are prepared on the surfaces, and the service performance of the bionic structures is improved. In addition, the method can also be suitable for strengthening the surfaces of various complex curved surface parts with the requirements of wear resistance, crack resistance and strengthening toughness, such as water turbine blades, rollers and the like.
When the gap between adjacent blocks is filled, the gap filling material is required to be well fused with the block material, and the gap filling material is required to be well fused with other blocks to fill the gap between the boundaries.
Example 1:
the bionic curved surface block-shaped net-shaped bimetal repairing structure of the tortoise shell comprises: shape-following additive layer 1, shape-following additive layer 1 is formed by the concatenation combination of a plurality of piecemeals 2, piecemeal 2 includes inside stereoplasm filled block 21 and the soft filled frame 22 in boundary gap, the soft filled frame 22 in boundary gap of piecemeal is the frame of the interior offset width d in the boundary of piecemeal 2, the soft filled frame 22 middle part in boundary gap is inside stereoplasm filled block 21.
The preparation method of the partitioned net-shaped bimetallic repair structure based on the turtle shell bionic curved surface comprises the following steps:
carrying out offset layering on the obtained three-dimensional digital model of the profile of the defect area: carrying out curved surface bias inwards on the basis of the outermost curved surface of the profile defect area of the part to obtain a multi-layer biased curved surface set
Wherein the offset distance is the single-layer thickness h of the conformal additive layer 1, and the number of offset layers NL＝H/h；
step 3, planning a curved surface shape-following additive track: planning arc material increase forming curved surface block shape-following material increase tracks distributed along the curved surface profile shape-following according to the geometric structure characteristics of each curved surface block, so that the curved surface block shape-following material increase tracks uniformly cover each block; planning arc additive filling tracks distributed along the block boundaries according to the block boundary gap geometrical characteristics;
and 4, starting from the curved surface at the bottommost layer, performing shape-following additive repair layer by layer from the top to the outside: the single-layer curved surface additive repairing method comprises the following steps: firstly, performing step 5, performing shape-following material increase on the areas in the blocks, then performing step 6, performing shape-following electric arc material increase filling on the block gap areas, and performing material increase repair on the next layer after the material increase repair of the whole layer of the curved surface is completed until the repair of all the material increase curved surface layers is completed;
step 5, carrying out shape-following material increase on the areas in the blocks: selecting a welding material with hardness, strength and wear resistance, and forming hard material blocks on the curved surface by shape-following material increase according to the curved surface block shape-following material increase track planned in the step 3, so that the material increase gradually covers each block until all blocks of the layer are subjected to material increase;
step 6, block gap area shape-following additive filling: and (3) selecting a welding material with toughness and plasticity, filling the block gaps with a soft material gap according to the shape-following additive filling track of the curved surface block gaps planned in the step (3), and gradually filling the boundary gaps of the blocks until the gaps of the layer are completely filled.
The preparation method also comprises the following steps of 7, heat treatment and machining: when all the repairing of the additive curved surface layers in the step 4 is finished, tempering and stress relieving heat treatment is carried out on the part subjected to additive repairing: controlling the tempering temperature at 550 ℃, preserving heat for 8 hours, cooling to the room temperature of 25 ℃ along with the furnace, preserving heat for 8 hours at 550 ℃, tempering, cooling to the room temperature of 25 ℃ along with the furnace, and finishing tempering;
and then, designing a geometric model of the tempered part according to the profile, machining the repaired profile to obtain an accurate working profile, and polishing to finish repairing the part.
The step 5 adopts a Eureka 750 welding wire; the Eureka 735 welding wire is used in step 6.
Example 2:
example 2 is substantially the same as example 1 except that:
the block 2 is a polygonal plane or curved surface structure with the thickness of h.
In the step 2, the blocks of the complex curved surface realize the automatic division of the curved surface through a clustering algorithm to obtain a plurality of curved surface blocks Si,j(i∈[1,2,…NL],j∈[1,2,…MP])，MPthe number of blocks for a curved surface; firstly, dispersing the geometric curved surfaceFor the curved surface point cloud, determining a coefficient delta (delta belongs to [0, 1 ] in a subtraction clustering algorithm by modifying]) Determining the number of partitions MPDividing the curved surface point cloud into M by fuzzy C-means clustering algorithmPPartitioning, namely obtaining point cloud boundaries of all partitions through an alpha-shape algorithm to obtain a plurality of polygon partitions 2;
the smaller the value of the determination coefficient delta is, the more the number of the blocks is, the larger the area ratio of the boundary gap soft filling frame 22 in the block 2 is, the larger the proportion of the soft material in the conformal additive layer 1 is, and the stronger the toughness of the conformal additive layer 1 is; on the contrary, the larger the value of the determination coefficient δ is, the smaller the number of the blocks is, the larger the area ratio of the internal hard filling blocks 21 in the blocks 2 is, the larger the ratio of the hard materials in the conformal additive layer 1 is, and the larger the hardness of the conformal additive layer 1 is; the size of the block is adjusted by adjusting the value of the determination coefficient delta, so that the proportion adjustment of hard and soft materials is realized, and finally, the comprehensive mechanical properties of wear resistance and crack resistance of the material are adjusted.
In step 3, the track planning in the blocks is as follows: the tracks in the blocks are generated by adopting an equal residual height method and an equidistant surface offset method, the distance between adjacent tracks needs to be ensured to meet the requirement of the lapping distance of the electric arc additive welding bead, each area needs to be uniformly covered, and no track overlap or gap exists; taking the central contour line of the block 2 as a base line, taking 50% of the width W of the weld bead as an offset distance, gradually covering the block by a curve-on-surface equal-residual-height offset algorithm, and obtaining a plurality of curve tracks { Path } covering the whole block1,Path2,Path3,…PathKAnd K is the number of tracks, the tracks in each block on the curved surface are planned in sequence, and the gap width d is equal to 50-80% of the weld bead width W.
In the step 5, the welding material with hardness, strength and wear resistance needs to satisfy the following conditions: the hardness at normal temperature meets HRC 55-60, and the hardness at 400-700 ℃ meets HRC 40-45;
in the step 6, the welding material with toughness and plasticity needs to meet the following conditions: the hardness at normal temperature is HRC 35-40, the hardness at 400-700 ℃ is HRC 25-30, and the yield strength sigma issMore than 600MPa, elongation delta more than 17 percent and impact energy Akv>35J。
The welding wire GORE 3752-FCG is adopted in the step 5; and a GORE 3235-FCG welding wire is adopted in the step 6.
Example 3:
example 3 is substantially the same as example 2 except that:
at least two layers of the conformal additive layer 1 are attached to form a net-shaped bimetal repairing structure, and the single-layer thickness h of the conformal additive layer 1 is 2.0-4.0 mm.
RMD650 welding wires are adopted in the step 5; RMD535 welding wire is adopted in the step 6; the diameter is 1.6mm, the wire feeding speed is 6.5m/min, the welding voltage is 22.8V, the welding current is 230A, and the welding speed is 8 mm/s.
Claims (9)
1. The bionic curved surface block-shaped net-shaped bimetal repairing structure of the tortoise shell is characterized in that: the method comprises the following steps: shape-following additive layer (1), shape-following additive layer (1) is formed by a plurality of piecemeals (2) concatenation combination, piecemeal (2) are including inside stereoplasm filled block (21) and the soft frame (22) that fills in boundary gap, the soft frame that fills in boundary gap of piecemeal (22) is the frame of the inside offset width d in boundary of piecemeal (2), the soft frame that fills in boundary gap (22) middle part is inside stereoplasm filled block (21).
2. The turtle shell bionic curved surface block-shaped net-shaped bimetal repairing structure of claim 1, which is characterized in that:
the block (2) is of a polygonal plane or curved surface structure with the thickness of h.
3. The turtle shell bionic curved surface block-shaped net-shaped bimetal repairing structure of claim 2, which is characterized in that:
the shape-following additive layer (1) is attached to form a net-shaped double-metal repair structure, and the single-layer thickness h of the shape-following additive layer (1) is 2.0-4.0 mm.
4. The preparation method of the turtle shell bionic curved surface block-shaped net-shaped bimetal repair structure based on the claims 1, 2 or 3 is characterized in that:
the repairing method comprises the following steps:
step 1, obtaining a curved surface to be repaired; machining or cleaning a failure region of the part profile due to abrasion or cracks by a carbon arc gouging machine, and performing three-dimensional scanning on the cleaned part to obtain a three-dimensional digital model of the profile of the defect region of the part: firstly, carrying out coordinate alignment on a three-dimensional digital model obtained by scanning and an original design model of a part; then determining a part profile defect area through digital-to-analog comparison; finally, obtaining a three-dimensional digital model of the defect area through Boolean difference calculation, and determining the maximum depth H of the defect area;
carrying out offset layering on the obtained three-dimensional digital model of the profile of the defect area: carrying out curved surface bias inwards on the basis of the outermost curved surface of the profile defect area of the part to obtain a multi-layer biased curved surface set
Wherein the offset distance is the single-layer thickness h of the conformal additive layer (1), and the number of offset layers NL＝H/h；
Step 2, discrete blocking of the curved surface to be repaired: sequentially selecting the multiple layers of the offset curved surfaces to be repaired obtained in the step 1 from outside to inside, dividing each layer of the offset curved surfaces to be repaired into a plurality of sub-blocks (2), and if the boundary of each sub-block (2) is inwardly offset by a gap with the width of d, the gap between every two adjacent sub-blocks (2) is 2 d;
step 3, planning a curved surface shape-following additive track: planning arc material increase forming curved surface block shape-following material increase tracks distributed along the curved surface profile shape-following according to the geometric structure characteristics of each curved surface block, so that the curved surface block shape-following material increase tracks uniformly cover each block (2); planning arc additive filling tracks distributed along the boundary of the block (2) according to the geometric characteristics of the block boundary gap;
and 4, starting from the curved surface at the bottommost layer, performing shape-following additive repair layer by layer from the top to the outside: the single-layer curved surface additive repairing method comprises the following steps: firstly, performing step 5, performing shape-following material increase on the areas in the blocks, then performing step 6, performing shape-following electric arc material increase filling on the block gap areas, and performing material increase repair on the next layer after the material increase repair of the whole layer of the curved surface is completed until the repair of all the material increase curved surface layers is completed;
step 5, carrying out shape-following material increase on the areas in the blocks: selecting a welding material with hardness, strength and wear resistance, and forming hard material blocks on the curved surface by shape-following material increase according to the curved surface block shape-following material increase track planned in the step 3, so that the material increase gradually covers each block until all blocks of the layer are subjected to material increase;
step 6, block gap area shape-following additive filling: and (3) selecting a welding material with toughness and plasticity, filling the block gaps with a soft material gap according to the shape-following additive filling track of the curved surface block gaps planned in the step (3), and gradually filling the boundary gaps of the blocks until the gaps of the layer are completely filled.
5. The preparation method of the turtle shell bionic curved surface block-shaped net-shaped bimetal repair structure according to claim 4, characterized by comprising the following steps:
the preparation method also comprises the following steps of 7, heat treatment and machining: when all the repairing of the additive curved surface layers in the step 4 is finished, tempering and stress relieving heat treatment is carried out on the part subjected to additive repairing: controlling the tempering temperature at 550 ℃, preserving heat for 8 hours, cooling to the room temperature of 25 ℃ along with the furnace, preserving heat for 8 hours at 550 ℃, tempering, cooling to the room temperature of 25 ℃ along with the furnace, and finishing tempering;
and then, designing a geometric model of the tempered part according to the profile, machining the repaired profile to obtain an accurate working profile, and polishing to finish repairing the part.
6. The preparation method of the turtle shell bionic curved surface block-shaped net-shaped bimetal repair structure according to claim 4 or 5, characterized by comprising the following steps:
in the step 2, the blocks of the complex curved surface realize the automatic division of the curved surface through a clustering algorithm to obtain a plurality of curved surface blocks Si,j(i∈[1,2,…NL],j∈[1,2,…MP])，MPThe number of blocks for a curved surface; firstly, dispersing a geometric curved surface into a curved surface point cloud, and determining a coefficient delta (delta belongs to [0, 1 ] in a subtraction clustering algorithm by modifying]) Determining the number of partitions MPDividing the curved surface point cloud into M by fuzzy C-means clustering algorithmPPartitioning, namely obtaining point cloud boundaries of all partitions through an alpha-shape algorithm to obtain a plurality of polygon partitions (2);
the smaller the value of the determination coefficient delta is, the more the number of the blocks is, the larger the area proportion of the boundary gap soft filling frame (22) in the block (2) is, the larger the proportion of the soft material in the conformal additive layer (1) is, and the stronger the toughness of the conformal additive layer (1) is; conversely, the larger the value of the determination coefficient delta is, the smaller the number of blocks is, the larger the area ratio of the internal hard filling blocks (21) in the blocks (2) is, the larger the proportion of the hard material in the conformal additive layer (1) is, and the larger the hardness of the conformal additive layer (1) is; the size of the block is adjusted by adjusting the value of the determination coefficient delta, so that the proportion adjustment of hard and soft materials is realized, and finally, the comprehensive mechanical properties of wear resistance and crack resistance of the material are adjusted.
7. The preparation method of the turtle shell bionic curved surface block-shaped net-shaped bimetal repair structure according to claim 6, characterized by comprising the following steps:
in step 3, the track planning in the blocks is as follows: the tracks in the blocks are generated by adopting an equal residual height method and an equidistant surface offset method, the distance between adjacent tracks needs to be ensured to meet the requirement of the lapping distance of the electric arc additive welding bead, each area needs to be uniformly covered, and no track overlap or gap exists; taking the central contour line of the block (2) as a base line, taking 50% of the width W of the weld bead as an offset distance, gradually covering the block by a residual height offset algorithm such as a curve on a curved surface and the like, and obtaining a plurality of curve tracks { Path } covering the whole block1,Path2,Path3,…PathKAnd K is the number of tracks, the tracks in each block on the curved surface are planned in sequence, and the gap width d is equal to 50-80% of the weld bead width W.
8. The preparation method of the turtle shell bionic curved surface block-based reticular bimetallic repair structure according to claim 7, characterized in that:
in the step 5, the welding material with hardness, strength and wear resistance needs to satisfy the following conditions: the hardness at normal temperature meets HRC 55-60, and the hardness at 400-700 ℃ meets HRC 40-45;
in the step 6, the welding material with toughness and plasticity needs to meet the following conditions: the hardness at normal temperature is HRC 35-40, the hardness at 400-700 ℃ is HRC 25-30, and the yield strength sigma issMore than 600MPa, elongation delta more than 17 percent and impact energy Akv>35J。
9. The preparation method of the turtle shell bionic curved surface block-based reticular bimetallic repair structure according to claim 8, characterized in that:
in the step 5, RMD650, GORE 3752-FCG or Eureka 750 welding wire is adopted;
RMD535, GORE 3235-FCG or Eureka 735 welding wire is used in step 6.
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