CN113068421B

CN113068421B - In-situ high-frequency induction brazing method for guide pipe in airplane repair

Info

Publication number: CN113068421B
Application number: CN200910122118.0A
Authority: CN
Inventors: 张志强; 郭静
Original assignee: 5720 Factory Of Pla
Current assignee: 5720 Factory Of Pla
Priority date: 2009-07-31
Filing date: 2009-07-31
Publication date: 2012-03-14
Anticipated expiration: 2029-07-31

Abstract

The invention discloses a conduit in-situ high-frequency induction brazing method in aircraft repair, which limits brazing high temperature in a joint area through a special heating protective cover matched with conduits of various specifications, winds a flexible induction coil outside the protective cover and fixes the flexible induction coil by using a special clamp, the flexible induction coil is connected with a high-frequency cable, high-frequency power is transmitted remotely, and an infrared temperature measurement photoelectric technology is adopted to control brazing temperature, adjacent equipment cannot be influenced by the brazing high temperature, and high-quality brazing connection in a narrow space and with welding parameter closed-loop control is realized. The technology is suitable for manufacturing and repairing various guide pipes of military and civil aircrafts and rush repair of military aircrafts, is further developed and applied, and has popularization value in other fields.

Description

In-situ high-frequency induction brazing method for guide pipe in airplane repair

Technical Field

The invention belongs to the technical field of metal welding, and relates to an in-situ high-frequency induction brazing repair technology for an undetachable conduit on an airplane.

Background

In the field of aircraft repair, various ducts on an aircraft are required to be repaired during aircraft manufacturing and repair and maintenance, the ducts are used for transmitting aircraft operation and providing pipelines with power of fuel, lubrication, attitude action and the like for the aircraft, and like blood vessels of a human body, when the ducts are damaged or have faults, the aircraft can not fly normally, the flight safety is affected, and very serious results are caused.

Generally, when the airplane conduit is damaged, the conduit function is restored by adopting a method of dismounting and updating, the dismounting of the conduit causes the increase of a large amount of repair workload of the airplane, the repair period is prolonged, the repair cost is increased, and the airplane is even scrapped because part of important conduits cannot be dismounted. When a large number of guide pipes of Su-27 and Su-30 airplanes are repaired, the guide pipes cannot be detached for updating, so that the research on-board in-situ repair technology is carried out, and the performance of the guide pipes is very necessary to be restored.

Disclosure of Invention

The invention aims to solve the technical problem of providing an in-situ high-frequency induction brazing repair method for an airplane guide pipe, so as to solve various problems and defects caused by the dislocation updating of the airplane guide pipe and repair the undetachable guide pipe on an airplane body.

Because the position of the guide pipe is narrow and the surrounding environment is complex during the maintenance of the airplane, the brazing process (such as flame brazing and the like) which can cause the temperature rise of the nearby environment is not allowed to be adopted, and the invention adopts the mounting type high-frequency induction brazing process which has good process accessibility and does not have adverse effect on the surrounding environment, thereby realizing the repair of the on-board non-detachable guide pipe in the maintenance process of the airplane.

A method for in-situ high-frequency induction brazing of a guide pipe in airplane repair comprises the steps of selecting a through guide pipe joint according to a brazed guide pipe, selecting the process conditions of the brazed guide pipe, and selecting the brazing conditions according to stainless steel and titanium alloy guide pipes.

Selecting brazing conditions, heating a solder 4, a protective cover 5 and a clamp 6, winding a flexible induction coil 7 and an optical fiber temperature measuring optical sensor 8, wherein the heating protective cover 5 adopts two half split water-cooling protective covers, the flexible induction coil 7 is wound outside the protective cover, and an infrared temperature measuring head of the optical fiber temperature measuring optical sensor 8 is vertically inserted into the heating protective cover.

The process for brazing the guide pipe comprises the following process steps of roundness correction of the guide pipe in a welding area, cleaning of residual oil in the guide pipe, cleaning of an oxide film in a welding area, electroplating and nickel plating of an electric brush, assembling of a straight-through guide pipe joint, brazing and inspection:

the method for rounding the conduit 1 in the welding area, removing the oxide film in the welding area and plating nickel by an electric brush comprises the following steps: rounding an area which is not less than 25mm away from the end of the stainless steel conduit to be welded by using an on-machine conduit shape correcting tool, polishing by using sand paper with the granularity of 120-160 to remove an oxide film on the inner surface of the conduit, and carrying out brush plating nickel plating in the rounding section of the outer surface of the conduit, wherein the thickness of the nickel layer is (6-9) mu m;

the titanium alloy pipe end needs to be polished along the axial with the abrasive paper that accords with No. 600 before brazing, and the length of polishing includes the region of pipe surface apart from the end 50mm at least to wipe the deoiling with the cotton that is dipped in petrol, wipe the dewatering with the cotton that is dipped in absolute ethyl alcohol afterwards.

The assembly straight-through conduit joint is divided into an A-type joint 2 and a B-type joint 3, the diameter of the joints is larger (0.05-0.1) mm than that of the conduit to be welded, and the A-type joint is used for welding the conduit smaller than phi 10 mm; the B-type joint is used for welding the pipes with the diameter larger than phi 12 mm.

And (4) checking: visual inspection and X-ray inspection are carried out on 100% of the conduit soldered joint, a sealing test and a strength test are carried out according to relevant requirements, and the soldered joint with overproof defects is repaired by a one-time repeated heating method or replaced by a cutting method.

The method adopts two half split water-cooled protective covers, winds a flexible induction coil outside the protective covers, controls the brazing temperature by high-frequency power remote transmission and adopting an infrared temperature measurement photoelectric technology, realizes high-quality brazing connection of closed-loop control in a narrow space, does not radiate heat outside, does not influence adjacent equipment, and realizes welding protection of titanium alloy and stainless steel guide pipes; removing oil stains in the conduit by adopting a method of combining a liquid solvent circulating in the conduit with an inert gas phase; the special tool for rounding the ground and the onboard guide pipe is applied, so that the uniform brazing gap is ensured, and the brazing quality is improved; aiming at the difference of airplane maintenance and manufacturing process conditions, a guide pipe damage area is cut off, a welding area is rounded, and the wettability of brazing filler metal when the stainless steel guide pipe cannot be brazed under the normal nickel plating condition is improved by adopting an electric brush plating method; and the winding mode of the flexible induction coil outside the protective cover is adjusted to realize the repair of the conduit under any angle condition.

The process method of the invention achieves the function of repairing and recovering the guide pipe by the in-situ high-frequency induction brazing of the undetachable guide pipe on the airplane, improves the repair level of the airplane structure in China, greatly reduces the repair cost of the airplane, and is in the leading position in the field of airplane repair in China. The technique is suitable for manufacturing and repairing various conduits of military and civil aircrafts and rush-repair of war wounds of military aircrafts, and has popularization value in other fields.

Drawings

FIG. 1 is a flow chart of a high-frequency induction brazing process

FIG. 2A is a schematic view of a type of joint

FIG. 3B is a schematic view of a type of joint

FIG. 4 schematic illustration of induction brazing

Detailed Description

The repair process is described below with reference to a flow chart of a high-frequency induction brazing process for a guide tube on a Su-27 aircraft.

1. And opening a hatch cover of the damaged part of the guide pipe, filling clean and dry air into the hatch cover, and drying the fuel tank. And blowing off the hydraulic oil in the guide pipe, and simultaneously completely pumping out the fuel oil in the fuel tank.

2. The oil medium remained in the connected conduit on the cleaner.

3. Marking the position to be cut off, cutting the position to be cut off by using a special cutting tool, removing burrs, chamfering the inner diameter side of the pipe, and removing any foreign matters or chips on the inner surface and the outer surface of the pipe.

4. And a section of area which is not less than 25mm away from the end of the stainless steel guide pipe to be welded on the machine is rounded by using a shape correcting tool of the guide pipe on the machine.

Polishing by using sand paper with the granularity of 120-160 to remove an oxide film on the inner surface of the guide pipe, and performing brush plating nickel plating in a rounding section on the outer surface of the guide pipe before brazing, wherein the thickness of the nickel layer is (6-9) mu m;

need to follow the axial with the abrasive paper that accords with No. 600 before brazing to titanium alloy pipe end and polish, the length of polishing includes the region of pipe surface apart from the end 50mm at least to wipe the deoiling with the cotton that is dipped in petrol, wipe the dewatering with the cotton that is dipped in absolute ethyl alcohol afterwards.

5. The type of conduit coupling is selected according to the size of the brazed conduit, and for the type A and type B couplings, a pencil is used to line up the positions (according to the size shown in the figure) away from the ends of the conduit respectively, so that the butt joint is positioned at the center of the straight-through conduit coupling during assembly, and the offset of the butt joint relative to the center of the straight-through conduit coupling is not more than 1.5 mm. For the A-type joint, the butt gap should be controlled to be (0.2-2.0) mm, and for the B-type joint, the butt gap should be controlled to be (4.0-5.0) mm.

6. And (6) brazing. Selecting brazing conditions (see tables 1 and 2) according to the stainless steel and titanium alloy conduits, winding the flexible inductor coil on the heating protective cover, and ensuring tight inter-turn lamination. And vertically inserting an infrared temperature measuring head of the optical fiber temperature measuring optical sensor onto the heating protective cover. And opening an argon switch, ventilating the heating protective cover and the inner cavity of the catheter according to the flow in the tables 1 and 2, wherein the pre-blowing time is not less than 3min, and welding is carried out according to the brazing specification and including the technological parameters of heating time, brazing temperature, heat preservation time, gas flow, cooling time and the like.

7. And (6) checking. The conduit solder joint was subjected to 100% visual inspection and X-ray inspection, and a sealability test and a strength test were performed according to the relevant requirements. The soldered joint with overproof defects is repaired by a one-time repeated heating method or replaced by a cutting method.

TABLE 1 stainless steel conduit induction brazing installation type Process parameters

TABLE 2 Induction braze welding installation type technological parameters of titanium alloy conduit

Claims

1. An in-situ high-frequency induction brazing method for a conduit in aircraft repair comprises the following steps: select the brazing condition, heating solder (4), safety cover (5), anchor clamps (6), around flexible induction coil (7), optic fibre temperature measurement optical sensor (8), heating safety cover (5) adopt two halves to run from opposite directions water-cooling safety cover, the outer flexible induction coil (7) of winding of safety cover, the infrared temperature probe of optic fibre temperature measurement optical sensor (8) is pegged graft perpendicularly and is heated the safety cover on, its characterized in that: the method comprises the following process steps of roundness correction of a guide pipe in a welding area, cleaning of residual oil in the guide pipe, cleaning of an oxide film of a welding area, brush plating nickel plating, assembling of a straight-through guide pipe joint, brazing and inspection:

the method for rounding the pipe (1) in the welding area, clearing the oxide film in the welding area and plating nickel by an electric brush comprises the following steps: rounding an area which is not less than 25mm away from the end of the stainless steel conduit to be welded by using an on-machine conduit shape correcting tool, polishing by using sand paper with the granularity of 120-160 to remove an oxide film on the inner surface of the conduit, and carrying out brush plating nickel plating in the rounding section of the outer surface of the conduit, wherein the thickness of the nickel layer is (6-9) mu m;

2. A method according to claim 1, characterized in that the assembled straight-through duct joints are divided into a-type joints (2) and B-type joints (3), the diameter of the joints is larger (0.05-0.1) mm than the diameter of the duct to be welded, the a-type joints are used for ducts smaller than 10mm, and the butt gap is correspondingly controlled between (0.2-2.0) mm; the B-type joint is used for a catheter with the diameter larger than 12mm, and the butt joint clearance is controlled to be (4.0-5.0) mm;

the stainless steel conduit induction brazing installation type process parameters are heated to the brazing temperature within +10 s;

the titanium alloy conduit induction brazing installation type process parameters are as follows:

the allowable fluctuation range of the brazing temperature is (920-960) DEG C, and the time deviation of heating to the brazing temperature is +5 s.