CN115070061A - Laser repairing method for undercarriage cracks - Google Patents

Laser repairing method for undercarriage cracks Download PDF

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Publication number
CN115070061A
CN115070061A CN202210852347.3A CN202210852347A CN115070061A CN 115070061 A CN115070061 A CN 115070061A CN 202210852347 A CN202210852347 A CN 202210852347A CN 115070061 A CN115070061 A CN 115070061A
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laser
groove
crack
area
undercarriage
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Inventor
李超龙
杜鹏程
曹通
杨晨光
王伟
成星
李庆
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Xi'an Aerospace Electromechanical Intelligent Manufacturing Co ltd
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Xi'an Aerospace Electromechanical Intelligent Manufacturing Co ltd
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Priority to CN202210852347.3A priority Critical patent/CN115070061A/en
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    • BPERFORMING OPERATIONS; TRANSPORTING
    • B22CASTING; POWDER METALLURGY
    • B22FWORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F10/00Additive manufacturing of workpieces or articles from metallic powder
    • B22F10/20Direct sintering or melting
    • B22F10/25Direct deposition of metal particles, e.g. direct metal deposition [DMD] or laser engineered net shaping [LENS]
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B22CASTING; POWDER METALLURGY
    • B22FWORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F10/00Additive manufacturing of workpieces or articles from metallic powder
    • B22F10/60Treatment of workpieces or articles after build-up
    • B22F10/64Treatment of workpieces or articles after build-up by thermal means
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B22CASTING; POWDER METALLURGY
    • B22FWORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F7/00Manufacture of composite layers, workpieces, or articles, comprising metallic powder, by sintering the powder, with or without compacting wherein at least one part is obtained by sintering or compression
    • B22F7/06Manufacture of composite layers, workpieces, or articles, comprising metallic powder, by sintering the powder, with or without compacting wherein at least one part is obtained by sintering or compression of composite workpieces or articles from parts, e.g. to form tipped tools
    • B22F7/062Manufacture of composite layers, workpieces, or articles, comprising metallic powder, by sintering the powder, with or without compacting wherein at least one part is obtained by sintering or compression of composite workpieces or articles from parts, e.g. to form tipped tools involving the connection or repairing of preformed parts
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B33ADDITIVE MANUFACTURING TECHNOLOGY
    • B33YADDITIVE 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
    • B33Y10/00Processes of additive manufacturing
    • CCHEMISTRY; METALLURGY
    • C21METALLURGY OF IRON
    • C21DMODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D10/00Modifying the physical properties by methods other than heat treatment or deformation
    • C21D10/005Modifying the physical properties by methods other than heat treatment or deformation by laser shock processing
    • CCHEMISTRY; METALLURGY
    • C23COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23CCOATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C24/00Coating starting from inorganic powder
    • C23C24/08Coating starting from inorganic powder by application of heat or pressure and heat
    • C23C24/10Coating starting from inorganic powder by application of heat or pressure and heat with intermediate formation of a liquid phase in the layer
    • C23C24/103Coating with metallic material, i.e. metals or metal alloys, optionally comprising hard particles, e.g. oxides, carbides or nitrides
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B22CASTING; POWDER METALLURGY
    • B22FWORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F7/00Manufacture of composite layers, workpieces, or articles, comprising metallic powder, by sintering the powder, with or without compacting wherein at least one part is obtained by sintering or compression
    • B22F7/06Manufacture of composite layers, workpieces, or articles, comprising metallic powder, by sintering the powder, with or without compacting wherein at least one part is obtained by sintering or compression of composite workpieces or articles from parts, e.g. to form tipped tools
    • B22F7/062Manufacture of composite layers, workpieces, or articles, comprising metallic powder, by sintering the powder, with or without compacting wherein at least one part is obtained by sintering or compression of composite workpieces or articles from parts, e.g. to form tipped tools involving the connection or repairing of preformed parts
    • B22F2007/068Manufacture of composite layers, workpieces, or articles, comprising metallic powder, by sintering the powder, with or without compacting wherein at least one part is obtained by sintering or compression of composite workpieces or articles from parts, e.g. to form tipped tools involving the connection or repairing of preformed parts repairing articles

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • Physics & Mathematics (AREA)
  • Mechanical Engineering (AREA)
  • Thermal Sciences (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Optics & Photonics (AREA)
  • Composite Materials (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Laser Beam Processing (AREA)

Abstract

The invention discloses a laser repairing method for undercarriage cracks, which comprises the following steps: a. detecting the crack position and the crack damage characteristic of the undercarriage; b. performing groove machining on the crack area according to the crack damage characteristics to remove cracks, and cleaning a formed groove after the groove machining is completed; c. performing laser shock peening treatment on the to-be-repaired area of the groove to prefabricate a compressive stress in the to-be-repaired area of the groove, so that the release of the fatigue stress in the undercarriage is inhibited; d. adopting a coaxial laser annular powder feeding mode to feed cladding powder which is made of the same material as the undercarriage base material to a preset position of a groove to-be-repaired area from bottom to top in a layer-by-layer and line-by-line scanning repair mode, and continuously melting the cladding powder and the undercarriage base material by a laser beam to combine the cladding powder with a base body; e. flaw detection is carried out on the area repaired by laser cladding, and if the flaw detection result is good, the appearance of the undercarriage is trimmed; f. and processing the repaired area by adopting a laser shock peening processing mode again.

Description

Laser repairing method for undercarriage cracks
Technical Field
The invention relates to the technical field of laser processing, in particular to a laser repairing method for landing gear cracks.
Background
The landing gear of the airplane is an important part in the lifting process of the airplane, the stable performance of the landing gear directly influences whether the airplane can be normally used or not, and even potential hazards can be brought to the safety of the airplane and pilots, so that the design and the material selection of the landing gear not only require high strength and high rigidity, but also require small size, excellent fatigue performance and the like. The undercarriage is generally made of high-strength steel with the tensile strength of more than 1300MPa at the present stage, and the working environment of the parts is very severe in the service process, so that the undercarriage not only bears huge loads such as bending, torsion and extrusion, but also can be corroded by the external environment, the undercarriage is easy to have defects such as abrasion and cracks, and the service life of the undercarriage can be further influenced.
In the aerospace industry, a user often cannot obtain a design drawing of a part, so that the problems of long purchase period, high manufacturing cost of a single part, large resource waste and the like exist if the part is replaced. In order to ensure the normal use of the airplane, the defects such as cracks in the undercarriage are generally repaired by adopting a repair technology so as to avoid the major waste such as part scrapping caused by local damage. Because the landing gear bears the action of various external forces of bending, twisting and compressing for a long time in the service process, the landing gear is converged and intertwined to form complex fatigue stress, the traditional repairing method of the landing gear comprises thermal spraying, argon arc welding and the like, the defects of large heat affected zone, large residual stress and the like exist, in the repairing process, the fatigue stress change in the landing gear is not controlled, during hot working, fatigue stresses may be relieved, new defects, such as stress cracks and the like, and no matter what repair technology is adopted to repair the defects, the performance of the repair area is often lower than that of the original parent metal, so the part needs to be subjected to heat treatment to recover the performance of the repair area, however, some parts, such as turbine blades, may not be heat treated after machining is complete, and in addition, the heat treatment of the whole part may damage the finished matching surface and waste of resources is serious.
Disclosure of Invention
The invention aims to solve the technical problem of providing a landing gear crack laser repairing method which can avoid the adoption of part heat treatment to repair cracks and can effectively prevent new cracks from forming and expanding.
In order to solve the technical problem, the invention provides a laser repairing method for undercarriage cracks, which comprises the following steps:
step a, detecting the crack position and the crack damage characteristic of the undercarriage;
b, performing groove machining on the crack area according to the detected crack damage characteristics to remove cracks, and cleaning a formed groove after the groove machining is completed;
c, performing laser shock strengthening treatment on the to-be-repaired area of the groove to prefabricate the compressive stress in the to-be-repaired area of the groove so as to inhibit the fatigue stress in the undercarriage from releasing;
d, adopting a coaxial laser annular powder feeding mode to feed cladding powder which is made of the same material as the undercarriage base material to a preset position of a groove to-be-repaired area from bottom to top in a layer-by-layer track-by-track scanning repair mode, and continuously melting the cladding powder and the undercarriage base material by a laser beam to combine the cladding powder and the base body together;
e, flaw detection is carried out on the area subjected to laser cladding repair, and if the flaw detection result is good, the appearance of the undercarriage is trimmed;
and f, processing the repaired area by adopting a laser shock peening mode again.
The further technical scheme is as follows: in the step c, the parameters of the laser shock peening treatment are as follows: the laser pulse width is 15-25ns, and the laser power density is 3.5-6GW/cm 2 The diameter of laser beam spot is 4-5mm, and the lapping rate is 50%.
The further technical scheme is as follows: in the step c, the pressure stress prefabricated in the area of the groove to be repaired after the laser shock peening treatment is-450 to-100 MPa.
The further technical scheme is as follows: in the step d, the laser beam continuously melts the cladding powder and the landing gear base material, so that the cladding powder and the base body are combined together, and the method specifically comprises the following steps: in the same cladding layer, laser moves along the normal direction of the crack parallel to the area to be repaired, and cladding powder and the landing gear base material are melted.
The further technical scheme is as follows: in the step d, when the laser beam carries out cladding treatment, the temperature between the tracks and the temperature between the layers is 100-150 ℃.
The further technical scheme is as follows: in the step d, before the laser beam continuously melts and melts the cladding powder and the landing gear base material, the method comprises the following steps: and locally heating the area to be repaired to 150-200 ℃.
The further technical scheme is as follows: in the step f, the parameters of the laser shock peening treatment are as follows: the laser pulse width is 20-30ns, and the laser power density is 4.5-9 GW/cm 2 The diameter of laser beam spot is 2-3 mm, and the lapping rate is 60-70%.
The further technical scheme is as follows: in the step f, after laser shock peening, the prefabricated compressive stress of the repaired area is-650 to-300 MPa, and the Vickers hardness of the surface layer is more than 450 HV.
The further technical scheme is as follows: in the step b, the opening angle in groove processing is 90-120 degrees, and the included angle between the symmetrical center line direction of groove processing and the tangential direction of the crack is not more than 15 degrees.
The further technical scheme is as follows: in the step b, after the groove is machined, the width of the bottom of the groove is not less than 2mm, and the surface roughness of the to-be-repaired area of the groove is not more than Ra3.2.
The invention has the beneficial technical effects that: compared with the prior art, the undercarriage crack laser repairing method carries out laser shock strengthening treatment on the to-be-repaired area of the undercarriage groove before cladding repair, prefabricates certain compressive stress in the to-be-repaired area, inhibits fatigue stress release in the undercarriage, effectively prevents new cracks from forming and expanding, adopts the laser cladding technology to repair the to-be-repaired area of the groove by scanning and repairing the to-be-repaired area layer by layer from bottom to top in a coaxial laser annular powder feeding mode, fully utilizes the characteristic of excellent performance of the deposition direction, reduces the risk of cracks appearing again in the repairing area in the service process of the undercarriage, finally adopts the laser to strengthen the shock repairing area and a heat affected area after the repairing area is processed, improves the hardness and the wear resistance of the repairing area, avoids heat treatment of parts, is suitable for repairing non-detachable components, and can be known that the undercarriage crack laser repairing method can avoid the cracks by adopting heat treatment of the parts, the repair process is simplified, the surface hardness of the material is improved, and the formation and the expansion of new cracks can be effectively prevented.
Drawings
FIG. 1 is a schematic flow diagram of a laser repair method for landing gear cracks according to the present invention.
Fig. 2 is a schematic view of the laser beam direction of the laser cladding process in embodiment 1 of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more clearly understood by those skilled in the art, the present invention is further described with reference to the accompanying drawings and examples.
Referring to fig. 1, fig. 1 is a schematic flow chart of a laser repairing method for the cracks of the landing gear. In the embodiment shown in the drawings, the landing gear crack laser repairing method comprises the following steps:
s101, detecting the crack position and the crack damage characteristic of the undercarriage.
In the step, a magnetic powder inspection method is adopted to quickly determine the area where the crack is located, and then an ultrasonic inspection method is adopted to determine the specific position of the crack and the crack damage characteristics such as depth, shape and size.
And S102, performing groove machining on the crack area according to the detected crack damage characteristics to remove the crack, and cleaning the formed groove after the groove machining is completed.
In the invention, the groove types can be divided into an annular groove and a plane groove according to the crack damage characteristics, and the groove processing mode can be that the annular groove and the plane groove are processed independently or the annular groove and the plane groove are combined.
In the step, the opening angle is 90-120 degrees during groove machining, and the included angle between the direction of the symmetrical center line of the groove machining and the tangential direction of the crack is not more than 15 degrees, namely the symmetrical line of the groove machining center is almost parallel to the tangential direction of the crack; after the groove is machined, the formed groove is an inclined groove, the section size from the bottom of the groove to the top of the groove is gradually increased, the width of the bottom of the groove is not less than 2mm, the surface roughness of the area to be repaired of the groove is not more than Ra3.2, so that the higher finish degree of the area to be repaired of the groove is kept, the cladding powder is well combined with the base material during laser cladding, and the defects of air holes, incomplete fusion and the like are avoided.
Understandably, flaw detection modes such as magnetic particle flaw detection, ultrasonic flaw detection, X-ray flaw detection and the like can be adopted for real-time flaw detection in the groove machining process, so that cracks are completely machined and removed; after the groove is processed, the groove can be cleaned by deionized water and/or acetone, alcohol and the like, and stains in the groove are removed.
S103, performing laser shock strengthening treatment on the to-be-repaired area of the groove to prefabricate the compressive stress in the to-be-repaired area of the groove, so that the fatigue stress release in the undercarriage is inhibited.
In the step, the parameters of the laser shock peening treatment are as follows: the laser pulse width is 15-25ns, and the laser power density is 3.5-6GW/cm 2 The diameter of a laser beam spot is 4-5mm, the lap joint rate is 50%, the single side of the laser shock range is 5-10mm larger than the groove, and the pressure stress prefabricated in the area to be repaired of the groove after the laser shock strengthening treatment is-450 to-100 MPa.
And S104, feeding the cladding powder made of the same material as the undercarriage base material to a preset position of a groove to-be-repaired area in a mode of scanning and repairing layer by layer from bottom to top in a coaxial laser annular powder feeding mode, and continuously melting the cladding powder and the undercarriage base material by a laser beam to combine the cladding powder and the base body together.
In this step, the laser beam constantly melts the cladding powder and the undercarriage substrate, and the combination of the cladding powder and the base body specifically includes: in the same cladding layer, laser moves along the normal direction of the crack parallel to the area to be repaired, cladding powder and the landing gear base material are melted, and the starting direction of laser cladding is changed in two adjacent cladding layers. Preferably, in the repair process, the powder which is not melted in the groove is removed in time, and the influence of the redundant powder on the next cladding is prevented.
Further, before the laser beam continuously melts the cladding powder and the landing gear substrate, the method comprises the following steps: locally heating the area to be repaired to 150-200 ℃; and when the laser beam carries out cladding treatment, the temperature between the tracks and the layers is 100-150 ℃.
Understandably, the laser cladding uses laser as a heat source, has the characteristics of small heat input, high cooling speed and the like, after the repair is finished by adopting a proper cladding process, the grain structure of a repair area is fine, and the laser cladding has the general characteristics of an additive manufacturing technology, namely the performance anisotropy of the deposition direction and the lap joint direction is realized, and the performance of the deposition direction is superior to the performance of the lap joint direction.
And S105, flaw detection is carried out on the area subjected to laser cladding repair, and if the flaw detection result is good, the appearance of the undercarriage is trimmed.
In the step, flaw detection modes such as magnetic powder flaw detection, ultrasonic flaw detection and X-ray flaw detection can be adopted to detect flaws in the repaired area, if the flaw detection result is good, the flaw detection result shows no flaws such as cracks and incomplete fusion, the undercarriage can be trimmed to the required size by means of machining, polishing and the like, and meanwhile the surface roughness of the laser cladding repaired area after trimming is guaranteed to be smaller than Ra3.2.
And S106, processing the repaired area again by adopting a laser shock peening processing mode.
In the step, the parameters of the laser shock peening treatment are as follows: the laser pulse width is 20-30ns, and the laser power density is 4.5-9 GW/cm 2 The diameter of a laser beam spot is 2-3 mm, and the lap joint rate is 60-70%; after laser shock strengthening treatment, the prefabricated compressive stress of the repaired area is-650 to-300 MPa, and the Vickers hardness of the surface layer is more than 450 HV.
Therefore, the laser shock treatment method disclosed by the invention has the advantages that the laser shock is carried out on the to-be-repaired area of the undercarriage before the laser cladding repair, a certain compression stress is prefabricated in the to-be-repaired area, the release of the fatigue stress formed by the action of external forces such as shock and vibration borne by the undercarriage in the service process can be inhibited, so that the formation and the expansion of new cracks can be effectively prevented, in addition, the anisotropy of additive manufacturing is fully utilized in the cladding repair process, the cracks are further inhibited from being generated again by utilizing the deposition direction with more excellent performance, meanwhile, the heat treatment of parts is also avoided, and the method is suitable for the repair of non-detachable components.
The landing gear crack laser repairing method is described in the following by combining specific embodiments.
Example 1
Aiming at the repair of the crack position in the fork area of the nose landing gear of the airplane, if the fork of the nose landing gear of the airplane is made of 30CrMnSiA high-strength steel, although powder made of other materials with higher strength can be adopted for repair, a primary battery can be formed at the heterogeneous repair contact position in a harsh service environment, and the corrosion and the cracking of the fork of the landing gear are accelerated. In this embodiment, adopt the same material powder to carry out crack defect restoration to avoid galvanic cell corrosion fracture scheduling problem, adopt laser shock supplementary simultaneously, improve the repair area performance, concrete repair flow is as follows:
(1) and (3) rapidly determining the area where the crack is located by adopting magnetic powder inspection, and then determining the specific position and depth of the crack by adopting ultrasonic inspection, wherein in the example, the crack position is located in the bifurcation area of the undercarriage, the length of the crack is 7 mm, and the depth of the crack is 1-2mm away from the detected surface.
(2) Before laser cladding repair, a groove needs to be machined in a crack area to remove crack defects in a base material, in this example, when the groove is machined, because a welding seam area of a wheel fork of a nose landing gear is a plane, the groove type selected in this embodiment is a plane groove, a central symmetry line of groove machining is parallel to a tangential direction of cracks, the width of the bottom of the groove is 2mm, the length of the groove is 7.5 mm, so that the cracks are completely wrapped and removed, preferably, an opening angle of the groove is 90 degrees during machining, so that the base material and the repair area are gradually transited, the edge performance of the repair area is ensured, and the surface roughness of the area to be repaired of the groove after machining is Ra3.2.
And magnetic particle inspection is adopted in the machining process, the groove machining area is detected in real time, so that the cracks are completely removed, deionized water is adopted to clean the inside of the groove after the groove is machined, machining pollution is removed, then acetone or alcohol is adopted to clean the groove immediately, no machining cutting fluid and other stains exist in the groove after cleaning is completed, no machining residues exist, and then the groove is naturally air-dried.
(3) And performing laser shock peening on the to-be-repaired area of the groove, wherein in the example, the parameters of the laser shock peening selected for the to-be-repaired area of the 30CrMnSiA steel are as follows: the laser pulse width is 15ns, and the laser power density is 4GW/cm 2 The diameter of a laser beam spot is 4mm, and the lap joint rate is 50 percent; after the laser shock strengthening is finished, the prefabricated compressive stress in the depth of 0.5mm of the area of the groove to be repaired is between-300 MPa and-200 MPa.
(4) Cleaning the groove until the interval is not more than 24 hours before laser cladding, selecting 30CrMnSiA steel powder with the same material as a raw material, wherein the particle size of the powder is normally distributed at 67-197 mu m, the sphericity of the powder is more than 90%, and the content of nonmetallic inclusions is less than 4 grains/100 g; and before laser cladding, heating the area to be repaired to 180 ℃ by adopting resistance heating, and then carrying out laser cladding, wherein X in coordinate axes represents a crack tangent direction, Y represents a crack normal direction, a line segment a represents a crack, and a dotted line n with an arrow represents an nth layer cladding direction, as shown in figure 2, the laser cladding is sequentially carried out along the parallel crack normal direction, in the cladding process, non-melted powder is immediately removed between adjacent passes, and when the cladding is carried out on adjacent passes, the temperature of the area to be repaired is not lower than 120 ℃.
(5) After the ultrasonic flaw detection is adopted to display that the flaw detection result is good, the shape of the undercarriage is trimmed to the selected size by adopting a four-axis machining center according to the size selection requirement of the part, and the surface roughness of the area after laser cladding repair after trimming is smaller than Ra3.2.
(6) And processing the repaired area by adopting a laser shock peening processing mode again, namely after the 30CrMnSiA steel is repaired, the parameters of the laser shock peening processing are as follows: the laser pulse width is 15ns, and the laser power density is 4GW/cm 2 The diameter of a laser beam spot is 4mm, and the lap joint rate is 50 percent; after the laser shock peening treatment is finished, the prefabricated pressure stress in the depth of 0.5mm of the to-be-repaired area of the groove is-300 MPa.
In conclusion, in the embodiment, after the wheel fork of the nose landing gear is subjected to laser composite repair, the internal fatigue stress of the part is converted into residual compressive stress of about-300 MPa, and the stability of the part can be improved. In the repairing process, various laser cladding anisotropies are fully utilized, and the deposition direction with more excellent performance is utilized to inhibit the re-growth of cracks in the service process.
Example 2
The aircraft main landing gear buffer sleeve is repaired by aiming at the crack position, the main landing gear buffer sleeve is made of 30CrMnSiNi2A high-strength steel, the crack position is centrally located in an annular welding seam area on a cylinder body, the buffer sleeve belongs to a whole non-detachable component, and the specific repairing process is as follows:
(1) and (3) rapidly determining the area where the crack is located by adopting magnetic powder inspection, and then determining the specific position and depth of the crack by adopting ultrasonic inspection, wherein in the example, the crack position is in a welding area, the length of the crack is 14.6 mm, the depth of the crack is 2-3 mm away from the detected surface, and the crack direction is parallel to the original welding line and is located in the sleeve annular welding line.
(2) In the example, when the groove is machined, because the welding seam area of the main landing gear buffer sleeve is an annular welding seam, the groove type selected in the embodiment is an annular groove, the central symmetry line of the groove machining is parallel to the tangential direction of the crack, the width of the bottom of the groove is 3mm, preferably, the opening angle of the groove during machining is 90 degrees, so that the base material and the repairing area are gradually transited, the edge performance of the repairing area is ensured, and the surface roughness of the to-be-repaired area of the groove after machining is Ra3.2.
And magnetic powder flaw detection is adopted in the machining process, the groove machining area is detected in real time, so that the cracks are completely removed, deionized water is adopted to clean the interior of the groove after the groove is machined, machining pollution is removed, then the groove is cleaned immediately by acetone or alcohol, after the cleaning is finished, no machining cutting fluid and other stains exist in the groove, no machining residues exist, and then the groove is naturally air-dried.
(3) Performing laser shock peening on the to-be-repaired area of the groove, wherein in the example, parameters of the laser shock peening selected for the to-be-repaired area of 30CrMnSiNi2A steel are as follows: the laser pulse width is 25ns, and the laser power density is 5.5GW/cm 2 The diameter of a laser beam spot is 3mm, and the lap joint rate is 60 percent; after the laser shock strengthening is finished, the prefabricated compressive stress in the depth of 0.5mm of the to-be-repaired area of the groove is-350 MPa.
(4) After the groove is cleaned until the interval before laser cladding is not more than 24 hours, selecting 30CrMnSiNi2A steel powder with the same material as a raw material, wherein the particle size of the powder is in normal distribution at 67-197 mu m, the sphericity of the powder is more than 92%, and the content of nonmetallic inclusions is less than 3 grains/100 g; before laser cladding, heating the area to be repaired to 180 ℃ by adopting resistance heating, then carrying out laser cladding, and immediately removing unfused powder between adjacent passes in the cladding process, wherein the temperature of the area to be repaired is not lower than 120 ℃ when cladding is carried out on the adjacent passes.
(5) After the ultrasonic flaw detection is adopted to display that the flaw detection result is good, the shape of the undercarriage is trimmed to the selected size by adopting a four-axis machining center according to the size selection requirement of the part, and the surface roughness of the area after laser cladding repair after trimming is smaller than Ra3.2.
(6) And processing the repaired area by adopting a laser shock peening processing mode again, namely after the 30CrMnSiNi2A steel is repaired, the parameters of the laser shock peening processing are as follows: laser pulse width of 15ns and laser power densityIs 4GW/cm 2 The diameter of a laser beam spot is 4mm, and the lap joint rate is 50%; after the laser shock peening treatment is finished, the prefabricated compressive stress in the depth of 0.5mm of the to-be-repaired area of the groove is-340 MPa.
In conclusion, in the embodiment, the repair of the main landing gear buffer sleeve assembly level component can be realized, after the laser composite repair, the matching surface is well matched, no deformation occurs, and the sealing performance of the part is good. Meanwhile, the implementation example avoids part heat treatment, simplifies the repair process, improves the surface hardness of the material, refines surface grains and meets the use requirement of the component.
The foregoing is considered as illustrative of the preferred embodiments of the invention and is not to be construed as limiting the invention in any way. Various equivalent changes and modifications can be made by those skilled in the art based on the above embodiments, and all equivalent changes and modifications within the scope of the claims should fall within the protection scope of the present invention.

Claims (10)

1. A method of laser repair of landing gear cracks, comprising:
step a, detecting the crack position and the crack damage characteristic of the undercarriage;
b, performing groove machining on the crack area according to the detected crack damage characteristics to remove cracks, and cleaning a formed groove after the groove machining is completed;
c, performing laser shock strengthening treatment on the to-be-repaired area of the groove to prefabricate the compressive stress in the to-be-repaired area of the groove so as to inhibit the fatigue stress in the undercarriage from releasing;
d, adopting a coaxial laser annular powder feeding mode to feed cladding powder which is made of the same material as the undercarriage base material to a preset position of a groove to-be-repaired area from bottom to top in a layer-by-layer track-by-track scanning repair mode, and continuously melting the cladding powder and the undercarriage base material by a laser beam to combine the cladding powder and the base body together;
e, flaw detection is carried out on the area subjected to laser cladding repair, and if the flaw detection result is good, the appearance of the undercarriage is trimmed;
and f, processing the repaired area by adopting a laser shock peening processing mode again.
2. The landing gear crack laser repairing method according to claim 1, wherein in the step c, the parameters of the laser shock peening treatment are as follows: the laser pulse width is 15-25ns, and the laser power density is 3.5-6GW/cm 2 The diameter of laser beam spot is 4-5mm, and the lapping rate is 50%.
3. The landing gear crack laser repairing method according to claim 1, wherein in the step c, the pressure stress prefabricated in the area to be repaired of the groove after the laser shock peening treatment is-450 to-100 MPa.
4. The landing gear crack laser repairing method of claim 1, wherein in the step d, the laser beam continuously melts the cladding powder and the landing gear substrate, and the step of combining the cladding powder and the substrate specifically comprises the steps of: in the same cladding layer, laser moves along the normal direction of the crack parallel to the area to be repaired, and cladding powder and the landing gear base material are melted.
5. The landing gear crack laser repairing method according to claim 4, wherein in the step d, the temperature between the roads and the layers is 100-150 ℃ when the laser beam is subjected to cladding treatment.
6. The landing gear crack laser repairing method according to claim 1, wherein the step d comprises, before the laser beam continuously melts the cladding powder and the landing gear substrate: and locally heating the area to be repaired to 150-200 ℃.
7. The landing gear crack laser repairing method according to claim 1, wherein in the step f, the parameters of the laser shock peening treatment are as follows: the laser pulse width is 20-30ns, and the laser power density is 4.5-9 GW/cm 2 The diameter of laser beam spot is 2-3 mm, and the lap-joint ratio is 60-70%。
8. The landing gear crack laser repairing method according to claim 7, wherein in the step f, after the laser shock peening treatment, the prefabricated compressive stress in the repaired area is-650 to-300 MPa, and the Vickers hardness of the surface layer is more than 450 HV.
9. The landing gear crack laser repairing method according to claim 1, wherein in the step b, the opening angle in groove machining is 90-120 degrees, and the included angle between the direction of the symmetrical center line of the groove machining and the tangential direction of the crack is not more than 15 degrees.
10. The landing gear crack laser repairing method according to claim 1, wherein in the step b, after the groove is machined, the width of the bottom of the groove is not less than 2mm, and the surface roughness of the to-be-repaired area of the groove is not more than Ra3.2.
CN202210852347.3A 2022-07-20 2022-07-20 Laser repairing method for undercarriage cracks Pending CN115070061A (en)

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CN101403114A (en) * 2008-10-24 2009-04-08 江苏宏大特种钢机械厂 Surface crack renovation method for key elements of chain grate
CN102489879A (en) * 2011-11-18 2012-06-13 江苏大学 Life prolonging method for quickly repairing microcracks of pump parts and life prolonging device for quickly repairing microcracks of pump parts
CN103409758A (en) * 2013-07-12 2013-11-27 江苏大学 Method for prolonging life of pump shells and blades by carrying out laser strengthening micro-cracks
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CN117031873B (en) * 2023-09-28 2024-01-05 上海传芯半导体有限公司 Repairing method and repairing device

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Application publication date: 20220920