CN-121972813-A - Laser material increasing and decreasing composite forming method for ultra-high strength steel deep blind hole piece

CN121972813ACN 121972813 ACN121972813 ACN 121972813ACN-121972813-A

Abstract

The invention relates to the technical field of metal additive manufacturing, in particular to a laser material increasing and decreasing composite forming method for ultra-high strength steel deep blind hole parts, which establishes an initial axial reference through a guide hole in an alternating manner of laser material increasing and numerical control milling, the heat input distribution is controlled by circularly increasing and decreasing materials, the heat transfer path is actively guided by the heat conduction ridge and the stress release groove, the milling depth is dynamically corrected by taking the small end face as a unified measurement reference, and the tissue homogenization and the size convergence are completed by assisting with vacuum annealing and laser micro plastic deformation. Therefore, the inner cavity of the deep blind hole always keeps controllable geometric outline, continuous interlayer combination and uniform tissue state in the layer-by-layer forming process, and the technical problem that the precision and the quality are difficult to cooperatively guarantee in the ultra-high strength steel deep blind hole forming is effectively solved.

Inventors

XIANG LIN
CHEN QIANG
RAN XUDONG
TAO JIANQUAN
WAN YUANYUAN
LEI WEI
ZHANG FEIYUE
SUN JIPENG

Assignees

中国兵器装备集团西南技术工程研究所

Dates

Publication Date: 20260505
Application Date: 20260316

Claims (10)

1. The laser material increasing and decreasing composite forming method for the ultra-high strength steel deep blind hole piece is characterized by comprising the following steps of: providing a closed ultra-high strength steel substrate, machining an annular groove and a guide hole on the small end surface of the substrate, clamping the substrate, and aligning a laser beam to be coaxial with the guide hole; Taking the bottom surface of the annular groove as a reference, and adopting laser coaxial wire feeding to carry out first layer cladding in the guide hole to form a first layer cladding ring; Step three, taking the first layer cladding ring as a reference, circularly executing material adding and material subtracting operations, carrying out laser cladding layer by layer to form a plurality of layers of cladding rings, milling the inner cavity once after each three layers of cladding rings are completed, and circularly propelling the depth of the inner cavity; forming a heat conduction ridge on the outer edge of the cladding layer of the closing-in transition section, and reserving the heat conduction ridge in subsequent milling; Turning the profile of the inner cavity into an inverted cone shape in a small end sealing area, and milling an axial stress release groove in the cladding layer; setting a rough milling end point based on the actually measured flatness offset of the small end face of the substrate after the single-layer cladding is completed in the sealing area, and setting finish milling depth based on the actually measured allowance of the rough milling surface after the reserved allowance is roughly milled, so that the top face of the inner cavity is flush with the small end face of the substrate; Step seven, carrying out vacuum annealing treatment on the formed inner cavity; And step eight, performing size finishing on the annealed inner cavity by adopting laser-induced micro plastic deformation.
2. The laser increasing and decreasing material composite forming method for the ultra-high strength steel deep blind hole piece is characterized in that in the first step, the depth of the annular groove is 1.2 mm, the width of the annular groove is 3.6 mm, the diameter of the guide hole is 8.0 mm, the depth of the guide hole is 25 mm, three points on the inner wall of the guide hole are sampled through a contact measuring head when a laser beam is calibrated, the spatial offset of the axis of the hole is calculated, and the position of a laser head is corrected, so that the focus of the laser beam is located at the center of the bottom surface of the guide hole.
3. The method for compositely forming the ultra-high-strength steel deep blind hole piece by laser increase and decrease materials is characterized in that in the second step, spiral track scanning is adopted for first layer cladding, the diameter of the first ring is 2.4 mm, the diameter of the last ring is 7.8 mm, the single-ring pitch is 0.6 mm, four rings are scanned, the laser power 1850 watts, the scanning speed is 820 mm per minute, the wire feeding speed is 1.95 m per minute, and the top height of a formed first layer cladding ring is 1.45 mm and is completely fused with the bottom surface of an annular groove.
4. The method for composite forming of the ultra-high-strength steel deep blind hole piece by laser material increase and decrease according to claim 1, wherein in the third step, three layers of cladding parameters of each round of circulation are sequentially adjusted: the cladding laser power of the first layer 1850W, the scanning speed of 820 mm per minute and the wire feeding speed of 1.95 m per minute; The cladding laser power of the second layer is 1820W, the scanning speed is 860 mm per minute, and the wire feeding speed is 1.98 m per minute; The third layer cladding laser power is 1800W, the scanning speed is 890 mm per minute, the wire feeding speed is 2.01 m per minute, and the next layer cladding or inner cavity milling is carried out after cooling for 35 seconds after each layer cladding is completed.
5. The method for compositely forming the ultra-high-strength steel deep blind hole piece by laser increase and decrease materials is characterized in that in the third step, a hard alloy ball end milling cutter is adopted for milling an inner cavity, the rotating speed of a main shaft is 6200 rpm, the feeding speed is 480 mm/min, the axial cutting depth is 0.8 mm, and the radial cutting depth is 0.35 mm; The milling path is an Archimedes spiral line, the pitch is 0.12 mm, the initial radius and the final radius are dynamically set along with the current inner cavity depth, and the inner diameter of the inner cavity after milling is stabilized to be 8.4 mm and the tolerance is +/-0.03 mm.
6. The method for compositely forming the ultra-high-strength steel deep blind hole piece by increasing and decreasing materials is characterized in that in the fourth step, the heat conducting ridges are formed by overlapping cladding tracks and cosine modulation, the modulation amplitude is 0.18 mm, the period corresponds to eight circumference parts, the number of the heat conducting ridges is eight and are uniformly distributed along the circumference, the subsequent milling avoids the direction of the heat conducting ridges, milling is carried out in the other circumference areas, and the height of the heat conducting ridges is kept to be 0.15-0.18 mm.
7. The laser increasing and decreasing composite forming method for the ultra-high strength steel deep blind hole piece, which is disclosed in claim 1, is characterized in that in the fifth step, the cone angle of the inverted cone-shaped inner cavity is 12.5 degrees, the number of stress relief grooves is four, the stress relief grooves are distributed along the directions of 0 degree, 90 degrees, 180 degrees and 270 degrees of circumference, the groove width is 0.4 millimeter, the groove depth penetrates through the cladding thickness of the current layer, and vibration aging treatment is applied to the cladding layer after the stress relief grooves are milled, wherein the vibration frequency is 38 hertz, the vibration amplitude is 0.13 millimeter, and the duration is 110 seconds.
8. The laser increasing and decreasing material composite forming method for the ultra-high strength steel deep blind hole piece is characterized by comprising the steps of in the sixth step, calculating flatness offset by sampling nine points on the small end face of a substrate through a measuring head before rough milling, setting rough milling end point coordinates and reserving 0.15 millimeter allowance according to the flatness offset, setting finish milling cutting depth after the actual allowance is calculated by sampling sixteen points on the rough milling face through the measuring head before finish milling, wherein the finish milling adopts a double-spiral path, and the radius of an inner ring is 4.6 millimeters, the radius of an outer ring is 8.6 millimeters and the screw pitch is 0.08 millimeter.
9. The laser increasing and decreasing material composite forming method for the ultra-high strength steel deep blind hole piece, which is disclosed in claim 1, is characterized in that in the seventh step, vacuum annealing is performed in an environment with the vacuum degree being better than 5 x 10 -3 Pa, high-purity argon is filled into a furnace, the heating rate is 80 ℃ to 620 ℃ per hour, the heat preservation time is calculated according to the inner cavity depth by overlapping for 120 minutes according to 0.8 minute per millimeter, and argon is filled to normal pressure after the cooling rate is 40 ℃ to 200 ℃ per hour.
10. The laser increase-decrease material composite forming method for the ultra-high strength steel deep blind hole piece, which is disclosed in claim 1, is characterized in that in the eighth step, the inner diameter is measured at intervals of 10 mm along the axial direction of an inner cavity by a pneumatic measuring instrument before size finishing, average deviation of each section is calculated, laser finishing is performed by adopting laser with the wavelength of 1070 nanometers, the pulse width of 8 nanoseconds and the repetition frequency of 50 kilohertz, the spot diameter is 0.3 millimeter, the power is 1.8 watts, the scanning speed is 1200 millimeters per minute, the screw pitch is 0.2 millimeter, and the inner diameter of the inner cavity after finishing is controlled within the range of 8.400 millimeter +/-0.001 millimeter.

Description

Laser material increasing and decreasing composite forming method for ultra-high strength steel deep blind hole piece Technical Field The invention relates to the technical field of metal additive manufacturing, in particular to a laser material increasing and decreasing composite forming method for an ultra-high strength steel deep blind hole piece. Background In aviation, aerospace and nuclear power equipment, closed-type ultra-high strength steel deep blind hole pieces are often used as integrated structures with high load bearing and high sealing requirements. The parts have the characteristics of large length-diameter ratio, deep blind holes, remarkable wall thickness gradient change and the like, and the materials need to keep high strength and good plastic matching. In the prior art, the method mainly adopts two modes of boring the deep hole after integral forging or sectional manufacturing and welding assembly. The method is characterized in that the inner cavity of the deep hole is welded to form a heat affected zone, and the inner cavity of the deep hole is welded to the heat affected zone. Especially, the consistency of the geometric forming precision and the internal metallurgical quality of the inner cavity of the deep blind hole is difficult to be considered on the ultra-high strength steel material. Disclosure of Invention The invention aims to provide a laser material increasing and decreasing composite forming method for an ultra-high strength steel deep blind hole piece, which effectively solves the technical problem that the precision and the quality are difficult to cooperatively guarantee in the ultra-high strength steel deep blind hole piece forming. In order to achieve the purpose, the technical scheme adopted by the invention is that the laser material increasing and decreasing composite forming method for the ultra-high strength steel deep blind hole piece comprises the following steps: providing a closed ultra-high strength steel substrate, machining an annular groove and a guide hole on the small end surface of the substrate, clamping the substrate, and aligning a laser beam to be coaxial with the guide hole; Taking the bottom surface of the annular groove as a reference, and adopting laser coaxial wire feeding to carry out first layer cladding in the guide hole to form a first layer cladding ring; Step three, taking the first layer cladding ring as a reference, circularly executing material adding and material subtracting operations, carrying out laser cladding layer by layer to form a plurality of layers of cladding rings, milling the inner cavity once after each three layers of cladding rings are completed, and circularly propelling the depth of the inner cavity; forming a heat conduction ridge on the outer edge of the cladding layer of the closing-in transition section, and reserving the heat conduction ridge in subsequent milling; Turning the profile of the inner cavity into an inverted cone shape in a small end sealing area, and milling an axial stress release groove in the cladding layer; setting a rough milling end point based on the actually measured flatness offset of the small end face of the substrate after the single-layer cladding is completed in the sealing area, and setting finish milling depth based on the actually measured allowance of the rough milling surface after the reserved allowance is roughly milled, so that the top face of the inner cavity is flush with the small end face of the substrate; Step seven, carrying out vacuum annealing treatment on the formed inner cavity; And step eight, performing size finishing on the annealed inner cavity by adopting laser-induced micro plastic deformation. Preferably, in the first step, the depth of the annular groove is 1.2 mm, the width of the annular groove is 3.6 mm, the diameter of the guide hole is 8.0 mm, and the depth of the guide hole is 25 mm, when the laser beam is calibrated, three points on the inner wall of the guide hole are sampled through the contact type measuring head, the spatial offset of the axis of the hole is calculated, and the position of the laser head is corrected, so that the focus of the laser beam is positioned at the center of the bottom surface of the guide hole. Preferably, in the second step, the first layer is melted and scanned by adopting a spiral track, the diameter of the first circle is 2.4 mm, the diameter of the last circle is 7.8 mm, the pitch of the single circle is 0.6 mm, four circles are scanned, the laser power 1850 watts, the scanning speed is 820 mm/min, the wire feeding speed is 1.95 m/min, and the top height of the formed first layer melting and covering ring is 1.45 mm and is completely fused with the bottom surface of the annular groove. Preferably, in the third step, three-layer cladding parameters of each cycle are sequentially adjusted: the cladding laser power of the first layer 1850W, the scanning speed of 820 mm per minute and the wire feeding speed of 1.95 m p