CN-117817266-B - Supporting plate nut processing technology

CN117817266BCN 117817266 BCN117817266 BCN 117817266BCN-117817266-B

Abstract

The invention discloses a process for machining a supporting plate nut, and belongs to the technical field of aerospace fastener manufacturing. The process comprises the following steps of material preparation, turning, hot heading, solution heat treatment, turning, wire cutting, general milling, bench work, middle inspection, closing, stabilization and aging heat treatment, sand blasting, local annealing, fluorescence detection, metallographic examination, surface silver plating, performance test, total inspection, packaging and warehousing. The strength of the supporting plate nut is up to 1210MPa and the hardness is HRC32-42 through heat treatment procedures such as solution heat treatment, stabilization and aging heat treatment, and the closing section ensures the normal closing and locking, plays roles of anti-loosening and vibration resistance, ensures the structural integrity of the supporting plate nut, and further ensures the structural strength, rigidity and other mechanical properties of the supporting plate nut.

Inventors

XIAO MUQUAN
HUANG MINGZHONG
JI XIANG
WANG CHAOGUANG
ZHENG PINGPING
YANG FEN

Assignees

贵州航飞精密制造有限公司

Dates

Publication Date: 20260505
Application Date: 20231205

Claims (10)

1. A process for machining a support plate nut is characterized in that the support plate nut (1) comprises an internal thread section (11) and a flaring section (12), one end of the external circular surface of the internal thread section (11) is provided with a closing-in section (10), the other end of the internal thread section is provided with a D-shaped support plate (13), one end of the flaring section (12) is coaxially connected with one end, close to the D-shaped support plate (13), of the internal thread section (11), and the process for machining the support plate nut (1) comprises the following steps: (1) Preparing a bar material which is GH738 according to the external dimension of the supporting plate nut (1); (2) Turning, namely removing black oxide skin on the surface of the bar according to the size requirement of the blank formed by hot upsetting; (3) The hot upsetting step, in which a D-shaped supporting plate (13) is upsetted by adopting a high-frequency induction heating mode; (4) Solution heat treatment, namely placing the upsetting semi-finished product into a vacuum heat treatment furnace, heating to 850-860 ℃, preheating for 30-40 min, heating to 1040-1080+/-10 ℃, preserving heat for 60-90 min, and then air-cooling or oil-cooling; (5) Turning, namely turning the appearance of the internal thread section (11), the closing-in section (10) and the flaring section (12) according to a design drawing, turning a thread bottom hole of the internal thread section (11) and an inner hole of the flaring section (12), and then tapping the thread bottom hole; (6) Wire cutting, namely, according to a design drawing, cutting the appearance of the D-shaped supporting plate (13) in a wire cutting way; (7) Milling a small chamfer angle (130) on the D-shaped supporting plate (13) according to a design drawing; (8) Burring, removing a linear cutting remelting layer, and trimming an arc to ensure smooth transition at the tangent position; (9) The middle inspection, according to the design drawing, inspecting each size of the supporting plate nut (1); (10) Closing up, namely closing up the locking part of the part by an extrusion method, wherein a closed-up section (10) after closing up is in an elliptic or polygonal shape; (11) The stabilization and aging heat treatment, namely placing the closed supporting plate nut (1) in a vacuum heat treatment furnace, heating to 845+/-10 ℃, preserving heat for 3-5 hours, air-cooling, then heating the supporting plate nut (1) to 760+/-10 ℃, preserving heat for 16+/-1 hour, and air-cooling to ensure that the hardness of the supporting plate nut (1) reaches HRC 32-42; (12) Spraying fine sand to remove an oxide layer on the surface of the supporting plate nut (1); (13) Local annealing, namely, carrying out local annealing on the flaring section (12); (14) Fluorescence detection, namely checking that any plane mutation cannot be caused on the surface of the supporting plate nut (1), and the closing-in section (10) cannot have crack, folding or hairline defects; (15) Metallographic examination, namely checking metal streamline at the thread of the supporting plate nut (1), streamline at the transition of the D-shaped supporting plate (13), grain size and oxidation depth of the supporting plate nut (1), and whether phenomena of overheating, overburning, folding and cracking exist; (16) Surface silver plating, namely silver plating the surface of the supporting plate nut (1), wherein the silver plating thickness is 5-8 mu m; (17) Performance test, namely performing locking performance test, axial load test, rivet expansion test and push-out test on the supporting plate nut (1); (18) The total inspection, namely inspecting each size of the supporting plate nut (1) according to a design drawing; (19) Packaging and warehousing.
2. The process for manufacturing the pallet nut according to claim 1, wherein the step (3) is performed by upsetting the D-shaped pallet (13) and then finely upsetting the D-shaped pallet (13).
3. The process for manufacturing the supporting plate nut according to claim 1, wherein in the step (10), in the process of obtaining the closing-in section (10) by an extrusion method, a locking performance process test is required to determine a closing-in size, the closing-in size is measured in the middle of the closing-in section (10), and the thread gauge can be smoothly screwed into the closing-in section (10) for one and a half turns.
4. The process for machining the supporting plate nut according to claim 1, wherein after the step (13) is completed and the first flaring section (12) is locally annealed, a 60-DEG conical mandrel is adopted to perform a flaring test on the flaring section (12), and no crack at the flaring position is qualified when the diameter of the flaring is 1.2 times that of the original diameter.
5. The process for manufacturing a pallet nut according to claim 1, wherein after the step (13) is completed for the partial annealing of the first flared section (12), the flared section (12) is inspected by metallography for grain size of the material, the grain size is between 2-6, the grain size is substantially uniform, no distinct coarse and fine grain bands are generated, no overheating and over-firing occurs, the oxidation depth is not more than 0.01mm, and the partial annealing heat treatment parameters are cured after the first flared section is inspected to be qualified.
6. The process for manufacturing a pallet nut according to claim 1, wherein the step (13) of locally annealing the flared section (12) by means of high frequency induction heating comprises the steps of: step A, vertically installing and fixing a supporting plate nut (1) on a lifting platform (5) and ensuring that a flaring section (12) faces upwards; step B, setting the oscillation coefficient of the high-frequency induction heating equipment (4) to 300-400; Step C, lifting the supporting plate nut (1) through the lifting platform (5) until the flaring section (12) is aligned with the induction heating pipe (41) of the high-frequency induction heating equipment (4) in height; Step D, introducing argon directly above the supporting plate nut (1) to enable the supporting plate nut (1) to be covered in an argon atmosphere; E, starting high-frequency induction heating equipment (4) to heat the flaring section (12); And F, closing the high-frequency induction heating equipment (4), and cooling the flaring section (12) to below 200 ℃ in an argon atmosphere to finish annealing treatment of the flaring section (12).
7. The process for producing the supporting plate nut according to claim 6, wherein the high-frequency induction heating device (4) and the lifting platform (5) are arranged on the workbench (3); the high-frequency induction heating equipment (4) comprises a high-frequency induction generator (40) and an induction heating pipe (41), wherein both ends of the induction heating pipe (41) are connected with the high-frequency induction generator (40), the middle part of the induction heating pipe (41) is gradually coiled from outside to inside, and the central lines of the middle parts of the induction heating pipe (41) are on the same horizontal plane.
8. The process for manufacturing the supporting plate nut according to claim 7, wherein the induction heating pipe (41) is made of copper pipe with the pipe diameter of 3mm, and a copper sheet with the width of 1mm is arranged at the lower part of the inner side wall of the middle part of the induction heating pipe (41).
9. The process for machining the supporting plate nut according to claim 6, wherein the flow rate of argon in the step D is 4L/min-6L/min, the heating time of the flaring section (12) in the step E is 5S-8S, and the heating temperature is 800-900 ℃.
10. The process for processing the supporting plate nut according to claim 1, wherein after the surface of the supporting plate nut (1) is plated with silver in the step (16), the supporting plate nut (1) is placed at 650 ℃ for heat preservation for 4 hours, then compressed air of 0.3 MPa-0.4 MPa is sprayed out from a nozzle with the caliber of 1.5mm, and the compressed air is blown to the surface of the supporting plate nut (1) to cool the surface of the supporting plate nut rapidly, so that the silver layer cannot bulge or peel off; And (3) packaging the pallet nut (1) by adopting capacitor paper in the step (19), and then integrally placing the pallet nut in a vacuum packaging bag for vacuum packaging.

Description

Supporting plate nut processing technology Technical Field The invention relates to a process for processing a supporting plate nut, and belongs to the technical field of aerospace fastener manufacturing. Background In the field of aerospace fasteners, fasteners for connecting important parts in a high-temperature environment are required to have the characteristics of good mechanical performance and anti-loosening performance in the high-temperature environment, and convenience in installation, fixation, detachment and maintenance. The supporting plate nut is a novel fastener, is the integration of the riveting nut and the self-locking nut, and has the riveting function and the self-locking performance. As shown in figures 1 to 3, the middle part of the supporting plate nut 1 is provided with a D-shaped supporting plate 13, the D-shaped supporting plate 13 can effectively prevent the nut body from rotating in the processes of bolt installation and disassembly, the threaded part of the supporting plate nut 1 is closed and locked to play roles in looseness prevention and vibration resistance, the non-threaded end of the supporting plate nut 1 can be installed by single-side flaring riveting, the axial movement of the supporting plate nut is fixedly limited, good anti-torsion and looseness prevention performance is realized, and a solution is provided for fastening connection of parts which are narrow in space and cannot fix the nut. When the supporting plate nut 1 is riveted and installed, the flaring deformation of the flaring section 12 occurs under the effect of external riveting force to rivet the nut on the base body 2, and the flaring section 12 cannot generate cracks or cracks and other defects which affect the service performance of the product. The strength requirement of the supporting plate nut 1 is 1210MPa, the hardness requirement is HRC32-42, and the material is high-temperature alloy GH738. The Chinese patent document with the publication number of CN105465142A discloses a high-temperature alloy embedded self-locking nut component and a processing method thereof, and the method comprises the following steps of material preparation, material discharging, surface treatment, hot heading, deplating, annealing, numerical control turning, deburring, thread extrusion, numerical control turning, deburring, wire cutting, necking, aging, annealing, sand blasting, flaw detection, surface treatment, assembly, riveting, packaging and warehousing. The self-locking nut is made of a high-temperature alloy material A286, and the strength of the self-locking nut obtained by the processing method is more than or equal to 1100MPa. Although the materials used for the self-locking nut component and the materials used for the supporting plate nut belong to high-temperature alloys, the materials GH738 and A286 have essential differences in physical properties, mechanical properties and the like, so that the processing method and parameters are not suitable for processing the supporting plate nut made of the material GH738, the strength of the supporting plate nut reaches 1210MPa and the hardness of the supporting plate nut is HRC32-42, and in addition, the supporting plate nut comprises a D-shaped supporting plate which is not provided for the self-locking nut component, and the structural differences also lead to the failure of processing the supporting plate nut by adopting the processing method. Disclosure of Invention In order to solve the technical problems, the invention provides a process for processing a supporting plate nut. The invention is realized by the following technical scheme: The process for processing the support plate nut comprises an internal thread section and a flaring section, wherein one end of the external circular surface of the internal thread section is provided with a closing-in section, the other end of the internal thread section is provided with a D-shaped support plate, one end of the flaring section is coaxially connected with one end of the internal thread section, which is close to the D-shaped support plate, and the process for processing the support plate nut comprises the following steps: (1) Preparing a bar material with GH738 according to the outline dimension of the supporting plate nut; (2) Turning, namely removing black oxide skin on the surface of the bar according to the size requirement of the blank formed by hot upsetting; (3) Hot upsetting, namely upsetting the D-shaped supporting plate by adopting a high-frequency induction heating mode; (4) Solution heat treatment, namely placing the upsetting semi-finished product into a vacuum heat treatment furnace, heating to 850-860 ℃, preheating for 30-40 min, heating to 1040-1080+/-10 ℃, preserving heat for 60-90 min, and then air-cooling or oil-cooling; (5) Turning, namely turning the appearance of the internal thread section, the closing-in section and the flaring section according to a design drawing, turning a thread bott