CN103464907A - Method of connecting sheets by thermal self-pressing - Google Patents
Method of connecting sheets by thermal self-pressing Download PDFInfo
- Publication number
- CN103464907A CN103464907A CN2013103696513A CN201310369651A CN103464907A CN 103464907 A CN103464907 A CN 103464907A CN 2013103696513 A CN2013103696513 A CN 2013103696513A CN 201310369651 A CN201310369651 A CN 201310369651A CN 103464907 A CN103464907 A CN 103464907A
- Authority
- CN
- China
- Prior art keywords
- thin plate
- interface
- thin
- welding end
- attachment
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Images
Landscapes
- Pressure Welding/Diffusion-Bonding (AREA)
- Connection Of Plates (AREA)
Abstract
The invention relates to a method of connecting sheets by thermal self-pressing. The thermoplastic metal at the junction of the connectors is self-pressed, diffused and connected through thermoplastic stress-strain field generated by the temperature difference effect is formed between high-temperature metal in a heating region and cold metal around the high-temperature metal under the action of central heat source non-fusion heating for the connectors of sheets to be connected in the absence of external force. The method has the advantages that the defects such as as-cast structures, pores, cracks and impurities generated in welds during fusion welding of sheets can be avoided, no external force needs to be applied during connection, and the technological process is simple and is easy to implement.
Description
Technical field
The invention relates to the method for attachment of sheet material in welding field, relate in particular to the hot self-pressure method of attachment of a kind of thin plate.
Background technology
The connection of light sheet material mainly contains the methods of attachment such as melting and friction stir welding.Melting is utilize thermal source to heat and melt materials to be welded and dose material, materials to be welded and dose material and form permanent jointing through fusing, after solidifying.According to using the thermal source difference, existing melt welding method has: argon arc welding, Laser Welding, ion beam weldering and electron beam welding etc.Friction stir welding is under pressure, utilizes the mutual fricative frictional heat of welded piece contact-making surface, makes welded junction metal reach the thermoplasticity state, by intermetallic diffusion, with recrystallization, realizes a kind of welding method be connected.
When the light sheet material melting connects, because of the high temperature thermal cycle effect of thermal source at welding region, through melting/solidifying, produce as-cast structure in weld seam, after having welded, in weld seam, still may produce pore, defects i.e.cracks, the fracture and the fatigue behaviour that cause the fracture of joint to compare mother metal with fatigue behaviour obviously reduce, the postwelding heat treatment of need to being annealed could obtain the mechanical property suitable with mother metal, has increased production cycle and cost.
The as-cast structure and the defect that when the solid-state connection such as friction stir welding can be avoided melting, in weld seam, produce, and can obtain zones of different tissue and the comparatively uniform jointing of mechanical property with respect to joint made by flame welding, but, needing to apply external force in connection procedure, the technique implementation procedure is comparatively complicated.
Thus, the inventor, by means of being engaged in experience and the practice of relevant industries for many years, proposes the hot self-pressure method of attachment of a kind of thin plate, to overcome the defect of prior art.
Summary of the invention
The object of the present invention is to provide the hot self-pressure method of attachment of a kind of thin plate, the method is that solid phase connects, the defect such as produce as-cast structure and pore, crackle in the time of can avoiding the thin plate molten solder in weld seam and be mingled with, simultaneously in connection procedure, do not need to apply external force, technical process is simple, be convenient to realize.
The object of the present invention is achieved like this, the hot self-pressure method of attachment of a kind of thin plate, under the condition without External Force Acting, utilize thin plate joint integral rigidity to be connected under the non-melt heat effect of central heat source, thermal treatment zone high-temperature metal and form altitude temperature difference effect on every side between cold metal, utilize consequent thermo-elasto-plasticity stress-strain field, self compaction, diffusion and a connection of junction thermoplasticity state metal achieves a butt joint.
In a better embodiment of the present invention, the method at least comprises the following steps:
(1) set up the butt jointing thin integral rigidity;
By thin plate interface slitless connection to be connected, and by having assisted welding end to set up the integral rigidity between butt jointing thin;
(2) carry out non-melt heating;
Use central heat source welding end from auxiliary to start to move along interface, carry out non-melt heating, thermal treatment zone metal and produce the temperature difference on every side between cold metal under Source, and restraining because of the butt jointing thin integral rigidity, thereby produce the thermo-elasto-plasticity stress-strain field in the thermal treatment zone, the thermo-elasto-plasticity stress-strain field carries out self compaction to high-temperature region, interface place thermoplasticity state metal, realizes diffusion and is connected.
In a better embodiment of the present invention, in step (1) before, fine finishining thin plate interface to be connected, and thin plate closed butt joint to be connected is assemblied on weld jig.
In a better embodiment of the present invention, described fixture includes clamp base, clamp base is provided with two overhead gage crossbeams, described two overhead gage crossbeams be arranged in parallel along interface, and two overhead gage crossbeams are separately positioned on the both sides of thin plate interface and keep certain distance with interface; Be interval with a plurality of screwed holes on each overhead gage crossbeam, be provided with caging bolt in screwed hole.
In a better embodiment of the present invention, described fine finishining comprises the interface fine grinding and cleans.
In a better embodiment of the present invention, in step (1), described to have assisted welding end be part blanking before welding, add machined together with each thin plate to be connected in man-hour forms; On each thin plate to be connected, equal correspondence is provided with one and has assisted welding end; The described length of welding end of having assisted is determined according to the size of thin plate interface to be connected; Use the molten solder mode will assist welding end to weld suitable length, set up thus the integral rigidity between butt jointing thin.
In a better embodiment of the present invention, in step (1), the described welding end of having assisted is a connection piece be processed to form separately, then should assist welding end and two thin plates to be connected spot-welded together respectively, thereby sets up the integral rigidity of butt jointing thin; The described size of welding end of having assisted is determined according to the size of thin plate interface to be connected.
In a better embodiment of the present invention, described central heat source is electric arc, electron beam or laser.
In a better embodiment of the present invention, in step (2) afterwards, will assist the welding end excision.
From the above mentioned, the hot self-pressure method of attachment of thin plate of the present invention, under the condition without External Force Acting, utilize thin plate joint integral rigidity to be connected under the non-melt heat effect of central heat source, thermal treatment zone high-temperature metal and form altitude temperature difference effect on every side between cold metal, utilize consequent thermo-elasto-plasticity stress-strain field, self compaction, diffusion and a connection of junction thermoplasticity state metal achieves a butt joint; The defect such as produce as-cast structure and pore, crackle when the present invention can avoid the thin plate molten solder in weld seam and be mingled with does not need to apply external force in connection procedure, and technical process is simple, be convenient to realize simultaneously.
The accompanying drawing explanation
The following drawings only is intended to the present invention is done and schematically illustrates and explain, not delimit the scope of the invention.Wherein:
Fig. 1: for butt jointing thin integral rigidity in the present invention is set up mode one schematic diagram;
Fig. 2: for butt jointing thin integral rigidity in the present invention is set up mode two schematic diagrames;
Fig. 3: be A-A place sectional structure schematic diagram in Fig. 1;
Fig. 4: in the present invention during non-melt heating the thermo-elasto-plasticity stress-strain field produce schematic diagram;
Fig. 5: be the connection procedure schematic diagram of an embodiment in the present invention.
The specific embodiment
Understand for technical characterictic of the present invention, purpose and effect being had more clearly, now contrast accompanying drawing explanation the specific embodiment of the present invention.
The present invention proposes the hot self-pressure method of attachment of a kind of thin plate, under the condition without External Force Acting, utilize thin plate joint integral rigidity to be connected under the non-melt heat effect of central heat source, thermal treatment zone high-temperature metal and form altitude temperature difference effect on every side between cold metal, utilize consequent thermo-elasto-plasticity stress-strain field, self compaction, diffusion and a connection of junction thermoplasticity state metal achieves a butt joint.
As shown in Figure 1 to 4, the method at least comprises the following steps:
(1) sample is processed and is installed;
Fine finishining thin plate 1 interface to be connected (comprise the interface fine grinding and clean), and thin plate 1 closed butt joint to be connected is assemblied on weld jig 2; In the present embodiment, described fixture 2 includes clamp base 21, clamp base 21 is provided with two overhead gage crossbeams 22, and described two overhead gage crossbeams 22 be arranged in parallel along interface, and two overhead gage crossbeams 22 are separately positioned on the both sides of thin plate interface and keep certain distance with interface; Be interval with a plurality of screwed holes on each overhead gage crossbeam 22, be provided with caging bolt 221 in screwed hole.
While being installed, two thin plates 1 to be connected are placed on clamp base 21, thin plate 1 below arranges lower cushion block 23, and top arranges upper holder block 24, after the interface slitless connection, by caging bolt 221, thin plate is fixed; In the present embodiment, the effect of fixture 2 is that while preventing follow-up precast monolithic rigidity, the butt jointing thin face is out of shape outward, junction misalignment (not applying extruding force) while simultaneously preventing hot self-pressure connection, and therefore, it is too tight that caging bolt 221 herein needn't be twisted; In the present embodiment, overhead gage crossbeam 22 needs to select the position suitable from interface; Crossbeam from interface too away from, may cause misalignment in welding, from may affect temperature field close to too, so will determine as the case may be.
(2) set up the butt jointing thin integral rigidity;
Thin plate to be connected is installed after (interface slitless connection), will sets up the butt jointing thin integral rigidity.In the present embodiment, set up the butt jointing thin integral rigidity and can adopt both modes:
Mode one: as shown in Figure 1, in described thin plate 1 interface one side end correspondence to be connected, be provided with and assisted on each thin plate to be connected of welding end 11(all correspondence to be provided with one to have assisted welding end 11); (this assist welding end 11 to fall cut after hot self-pressure connection) that described to have assisted welding end 11 are part blankings before welding, add that man-hour, machined together with part formed; The described length of welding end 11 of having assisted is determined according to the size of thin plate interface to be connected; Use the molten solder mode that the welding end 11 of having assisted of two correspondences is welded to suitable length (length is too little, and the integral rigidity deficiency of buttcover plate may cause welding); Set up thus two integral rigidities between butt jointing thin.
Mode two: as shown in Figure 2, the described welding end of having assisted is a connection piece 12 be processed to form separately, should assist welding end (connector) 12 to separate with before thin plate 1 weldering to be connected, assist welding end 12 to be connected respectively (described a plurality of solder joints 3 as shown in Figure 2) with a side end of two butt jointing thin by the spot welding mode this, thereby set up the integral rigidity of butt jointing thin; The described size of welding end of having assisted is determined according to the size of thin plate interface to be connected.
(3) carry out non-melt heating;
Use electric arc, the central heat source such as electron beam or laser welding end 11 from auxiliary starts to move with suitable speed along interface, carry out non-melt heating, thermal treatment zone metal and produce the temperature difference on every side between cold metal under Source, and restraining because of the butt jointing thin integral rigidity, the expansion of thermal treatment zone high-temperature metal is subject to the extruding force F of cold metal on every side and the moment M effect in platen surface, produce the thermo-elasto-plasticity stress-strain field under extruding force F and moment M effect, the thermo-elasto-plasticity stress-strain field is pushed high-temperature region, interface place thermoplasticity metal, realize diffusion and be connected.As shown in Figure 4, in Fig. 4, B is the heating high-temperature region, and arrow C is the thermal source moving direction.Do not melt material to be connected in whole connection procedure, do not dose material, and do not apply external force.
Without under External Force Acting, thermal treatment zone high-temperature metal and the thermo-elasto-plasticity stress-strain field that the temperature difference acting in conjunction of cold metal is set up on every side while utilizing between butt jointing thin the non-melt heating of integral rigidity and thermal source, the self compaction, diffusion and the connection that realize treating jointing interface high-temperature region thermoplasticity state metal are the unique characteristics of the present invention.Between buttcover plate, integral rigidity and thermal treatment zone metal are to produce the thermo-elasto-plasticity stress-strain field to realize the necessary condition that the hot self-pressure of thin plate is connected with the temperature difference of cold metal on every side.
From the above mentioned, the hot self-pressure method of attachment of thin plate in present embodiment, not treating connecting material and apply external force (extruding force) in whole connection, is self compaction, diffusion and the connection of junction thermoplasticity state metal that achieve a butt joint of the thermo-elasto-plasticity stress-strain field that produces by storeroom integral rigidity to be connected and the local non-melt heating temperature difference.Therefore, the present invention compares mode of heating and to be connected mechanism all different from Solid-phase welding methods such as conventional diffusion weldering, friction stir welding and thermocompression bondings.On mode of heating, what the present invention selected is to utilize the melting thermal source to carry out non-melt local heat workpiece joint to be connected; Connecting on mechanism, high-temperature region metal and temperature difference acting in conjunction generation thermo-elasto-plasticity stress-strain field between cold metal on every side when the present invention is joint to be connected self integral rigidity that utilize to set up and the non-melt heated coupling of thermal source, extruding, diffusion and a connection of junction thermoplasticity state metal thus achieves a butt joint; Therefore, the present invention does not need to rely on externally applied forces effect or friction thermodynamic activity etc. in connection procedure to reach the purpose that joint connects as other existing method.
The present invention compared with prior art has following useful effect:
(1) with melting, compare:
1. non-melt heating, the as-cast structure produced in weld seam in the time of avoiding molten solder and pore and defects i.e.cracks.
(2) with the conventional diffusion weldering, compare:
1. do not need to apply external force; 2. do not need whole heating; 3. do not need long-time insulation; 4. technical process simple, be convenient to realize; 5. working (machining) efficiency is high.
Below with a specific embodiment, further illustrate the present invention.
As shown in Figure 5, butt jointing thin length L=60mm, width B=50mm, thickness of slab 2mm, the butt jointing thin material is the TC4 titanium alloy; Adopt the vacuum electron beam thermal source to carry out hot self-pressure connection, process is as follows:
(1) the interface fine grinding, be fixed on weld jig after cleaning up;
(2) utilize the welding initiating terminal (having assisted welding end) of electron beam welding prewelding butt jointing thin, molten solder length a=10mm, set up the buttcover plate integral rigidity;
(3) postwelding thin plate temperature fusion is reduced near room temperature, utilize the electron beam thermal source to start along the non-melt heating buttcover plate of interface from the welding initiating terminal, carry out hot self-pressure connection, relevant parameter is: operating distance H=335mm, line Ib=1.3mA, accelerating potential Ub=150kV, focus current If=2809mA, speed v=0.2mm/s.
The TC4 titanium-alloy thin-plate moves heat hot self-pressure jointing metallographic testing result and shows: after hot self-pressure connects, former interface disappears, only there is minority micron-scale rank hole in interface, and the seam rate that the present embodiment thin plate moves heat hot self-pressure jointing is greater than 95%.The tensile mechanical properties testing result shows: the tensile strength of joint is 1019.99MPa.
The foregoing is only the schematic specific embodiment of the present invention, not in order to limit scope of the present invention.Any those skilled in the art, the equivalent variations of having done under the prerequisite that does not break away from design of the present invention and principle and modification, all should belong to the scope of protection of the invention.
Claims (9)
1. the hot self-pressure method of attachment of thin plate, under the condition without External Force Acting, utilize thin plate joint integral rigidity to be connected under the non-melt heat effect of central heat source, thermal treatment zone high-temperature metal and form altitude temperature difference effect on every side between cold metal, utilize consequent thermo-elasto-plasticity stress-strain field, self compaction, diffusion and a connection of junction thermoplasticity state metal achieves a butt joint.
2. the hot self-pressure method of attachment of thin plate as claimed in claim 1, it is characterized in that: the method at least comprises the following steps:
(1) set up the butt jointing thin integral rigidity;
By thin plate interface slitless connection to be connected, and by having assisted welding end to set up the integral rigidity between butt jointing thin;
(2) carry out non-melt heating;
Use central heat source welding end from auxiliary to start to move along interface, carry out non-melt heating, thermal treatment zone metal and produce the temperature difference on every side between cold metal under Source, and restraining because of the butt jointing thin integral rigidity, thereby produce the thermo-elasto-plasticity stress-strain field in the thermal treatment zone, the thermo-elasto-plasticity stress-strain field carries out self compaction to high-temperature region, interface place thermoplasticity state metal, realizes diffusion and is connected.
3. the hot self-pressure method of attachment of thin plate as claimed in claim 2 is characterized in that: in step (1) before, and fine finishining thin plate interface to be connected, and thin plate closed butt joint to be connected is assemblied on weld jig.
4. the hot self-pressure method of attachment of thin plate as claimed in claim 3, it is characterized in that: described fixture includes clamp base, clamp base is provided with two overhead gage crossbeams, described two overhead gage crossbeams be arranged in parallel along interface, and two overhead gage crossbeams are separately positioned on the both sides of thin plate interface and keep certain distance with interface; Be interval with a plurality of screwed holes on each overhead gage crossbeam, be provided with caging bolt in screwed hole.
5. the hot self-pressure method of attachment of thin plate as claimed in claim 3 is characterized in that: described fine finishining comprises the interface fine grinding and cleans.
6. the hot self-pressure method of attachment of thin plate as claimed in claim 2 is characterized in that: in step (1), described to have assisted welding end be part blanking before welding, add machined together with each thin plate to be connected in man-hour forms; On each thin plate to be connected, equal correspondence is provided with one and has assisted welding end; The described length of welding end of having assisted is determined according to the size of thin plate interface to be connected; Use the molten solder mode will assist welding end to weld suitable length, set up thus the integral rigidity between butt jointing thin.
7. the hot self-pressure method of attachment of thin plate as claimed in claim 2, it is characterized in that: in step (1), the described welding end of having assisted is a connection piece be processed to form separately, then should assist welding end and two thin plates to be connected spot-welded together respectively, thereby set up the integral rigidity of butt jointing thin; The described size of welding end of having assisted is determined according to the size of thin plate interface to be connected.
8. the hot self-pressure method of attachment of thin plate as claimed in claim 2 is characterized in that: described central heat source is electric arc, electron beam or laser.
9. the hot self-pressure method of attachment of thin plate as claimed in claim 2 is characterized in that: in step (2) afterwards, will assist the welding end excision.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201310369651.3A CN103464907B (en) | 2013-08-22 | 2013-08-22 | Method of connecting sheets by thermal self-pressing |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201310369651.3A CN103464907B (en) | 2013-08-22 | 2013-08-22 | Method of connecting sheets by thermal self-pressing |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN103464907A true CN103464907A (en) | 2013-12-25 |
| CN103464907B CN103464907B (en) | 2015-06-17 |
Family
ID=49790071
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201310369651.3A Active CN103464907B (en) | 2013-08-22 | 2013-08-22 | Method of connecting sheets by thermal self-pressing |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN103464907B (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104842081A (en) * | 2015-05-18 | 2015-08-19 | 中国航空工业集团公司北京航空制造工程研究所 | Thick plate welding method and welding fixture |
| CN112045294A (en) * | 2020-09-01 | 2020-12-08 | 中国航空制造技术研究院 | Rigid restraint thermal self-pressure diffusion connection method and device for local induction heating |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5334657A (en) * | 1976-09-13 | 1978-03-31 | Mitsubishi Heavy Ind Ltd | Method of bonding metallic thin plates |
| SU923791A1 (en) * | 1980-02-26 | 1982-04-30 | Le Elektromashino | Clamping apparatus for preweld assembling of thin-sheet products for butt welding |
| US4912295A (en) * | 1987-08-27 | 1990-03-27 | Sumitomo Metal Industries, Ltd. | Butt welding method |
| JP2005007466A (en) * | 2003-06-20 | 2005-01-13 | Mitsubishi Heavy Ind Ltd | Friction stir welding method and apparatus, and structure manufactured by the method |
-
2013
- 2013-08-22 CN CN201310369651.3A patent/CN103464907B/en active Active
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5334657A (en) * | 1976-09-13 | 1978-03-31 | Mitsubishi Heavy Ind Ltd | Method of bonding metallic thin plates |
| SU923791A1 (en) * | 1980-02-26 | 1982-04-30 | Le Elektromashino | Clamping apparatus for preweld assembling of thin-sheet products for butt welding |
| US4912295A (en) * | 1987-08-27 | 1990-03-27 | Sumitomo Metal Industries, Ltd. | Butt welding method |
| JP2005007466A (en) * | 2003-06-20 | 2005-01-13 | Mitsubishi Heavy Ind Ltd | Friction stir welding method and apparatus, and structure manufactured by the method |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104842081A (en) * | 2015-05-18 | 2015-08-19 | 中国航空工业集团公司北京航空制造工程研究所 | Thick plate welding method and welding fixture |
| CN112045294A (en) * | 2020-09-01 | 2020-12-08 | 中国航空制造技术研究院 | Rigid restraint thermal self-pressure diffusion connection method and device for local induction heating |
Also Published As
| Publication number | Publication date |
|---|---|
| CN103464907B (en) | 2015-06-17 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN101282814B (en) | Hybrid laser and resistance welding system and method | |
| CN100556602C (en) | The method of soldering of ultrasonic wave auxiliary laser or laser braze-welding | |
| CN104625411B (en) | A kind of Ti2The method of AlNb base intermetallic compound and xenogenesis titanium alloy welding | |
| CN101468419B (en) | Induction and electrical arc composite heat source stud welding method | |
| CN104070287A (en) | Method and device for restraining softening of high-strength aluminum alloy stirring friction welding joint | |
| CN102892545B (en) | Beam welding method, vacuum packaging method, and vacuum heat-insulation material produced by vacuum packaging method | |
| KR102328270B1 (en) | Resistance spot welding joint of aluminum material, and resistance spot welding method of aluminum material | |
| JP2009241136A (en) | Series spot or indirect spot welding method for high tensile strength steel sheet | |
| CN108544062B (en) | Automatic welding method for aluminum alloy sheet | |
| CN103831533A (en) | Titanium alloy laser-MIG composite welding method | |
| CN102909479B (en) | Square long girder steel welding method | |
| JP2009226454A (en) | Method and apparatus of joining metallic member | |
| CN104942428A (en) | Hydraulic cylinder friction welding production technology | |
| CN110142496B (en) | TiAl/Ti added with Y-shaped intermediate layer3Electron beam welding method for Al dissimilar material | |
| CN103464907B (en) | Method of connecting sheets by thermal self-pressing | |
| CN101711192A (en) | Method and device for permanently interconnecting components from a heat-meltable metal material | |
| CN103624393B (en) | The hot self-pressure method of attachment of rigid restraint | |
| CN111014938B (en) | Friction stir welding implementation process for car roof or car underframe | |
| KR20220156626A (en) | How to join metal materials | |
| JP5814906B2 (en) | Resistance welding method and resistance welding apparatus | |
| CN110142495B (en) | Titanium-aluminum alloy electron beam welding method for reducing dilution rate of parent metal | |
| JP2006130562A (en) | Method for repairing hole of metallic workpiece | |
| CN107160019A (en) | The welder and method of a kind of micro-channel heat sink for semi-conductor laser lamination | |
| CN105397279A (en) | Welding method of copper-chromium load switch component | |
| JP2011194459A (en) | Indirect spot welding method |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C06 | Publication | ||
| PB01 | Publication | ||
| C10 | Entry into substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| CP01 | Change in the name or title of a patent holder | ||
| CP01 | Change in the name or title of a patent holder |
Address after: 100024 North East military villa, eight Li bridge, Chaoyang District, Beijing Patentee after: China Institute of Aeronautical Manufacturing Technology Address before: 100024 North East military villa, eight Li bridge, Chaoyang District, Beijing Patentee before: Beijing Aviation Manufacturing Engineering Institute of China Aviation Industry Group Company |