阅读说明：本技术 一种大型飞机蒙皮毛坯结构及蒙皮拉形成型方法 (Large aircraft skin blank structure and skin stretch forming method ) 是由 刘晓臻 熊旭 胡雅玲 黄旭林 蒋欢 于 2019-10-08 设计创作，主要内容包括：本发明涉及一种航空钣金零件及其成型方法,属于航空制造技术领域。一种大型飞机蒙皮毛坯结构,蒙皮毛坯的端头在拉伸方向具有向外侧凸起的结构。一种蒙皮拉形成型方法,所述蒙皮为上述所述的蒙皮毛坯结构,包括以下步骤：步骤一：将拉形机钳口抬起一定角度并弯曲,将蒙皮毛坯两端夹持在拉形机钳口之内；步骤二：使拉形机钳口在水平方向上相向运动,使蒙皮毛坯翘曲；步骤三：降低拉形机钳口高度,将蒙皮毛坯与蒙皮拉形模形面接触；步骤四：使拉形机钳口在水平方向上朝远离蒙皮拉形模的方向做拉伸运动,将蒙皮毛坯与蒙皮拉形模形面完全拉伸贴合,即可。本发明具有如下优点：提高了蒙皮质量,从而实现了更优异的飞机气动外形。(The invention relates to an aviation sheet metal part and a forming method thereof, and belongs to the technical field of aviation manufacturing. The end of the skin blank has a structure protruding outwards in the stretching direction. A skin stretch forming method is provided, wherein the skin is the skin blank structure, and the method comprises the following steps: the method comprises the following steps: lifting the jaw of the stretch-forming machine by a certain angle and bending, and clamping two ends of the skin blank in the jaw of the stretch-forming machine; step two: making the jaw of the stretch-forming machine move oppositely in the horizontal direction to warp the skin blank; step three: reducing the height of a jaw of the stretch-forming machine, and contacting the skin blank with the skin stretch-forming die surface; step four: and (3) stretching the jaw of the stretch forming machine in the horizontal direction towards the direction far away from the skin stretch forming die, and completely stretching and fitting the skin blank and the skin stretch forming die surface. The invention has the following advantages: the skin quality is improved, and therefore the more excellent aerodynamic appearance of the airplane is achieved.)

1. The utility model provides a jumbo skin blank structure which characterized in that: the end of the skin blank has a structure protruding outwards in the stretching direction.

2. The large aircraft skin blank structure according to claim 1, wherein: the structure protruding towards the outside is an arc protrusion.

3. The skin blank structure of the large airplane as claimed in claim 2, wherein the maximum chord height of the circular arc protrusion of the skin blank is 3% ~ 5% of the maximum throat depth of the jaw of the stretch-forming machine.

4. The large aircraft skin blank structure according to claim 2, wherein: the highest part of the arc convex chord height of the skin blank and the maximum part of the shape radian of the skin surface are positioned on the same straight line parallel to the stretching movement direction of the jaw of the stretch-forming machine.

5. A skin stretch forming method is characterized in that: the skin is the skin blank structure of any one of claims 1 to 4, comprising the steps of:

the method comprises the following steps: lifting the jaw of the stretch-forming machine by a certain angle and bending, and clamping two ends of the skin blank in the jaw of the stretch-forming machine;

step two: making the jaw of the stretch-forming machine move oppositely in the horizontal direction to warp the skin blank;

step three: reducing the height of a jaw of the stretch-forming machine, and contacting the skin blank with the skin stretch-forming die surface;

step four: and (3) stretching the jaw of the stretch forming machine in the horizontal direction towards the direction far away from the skin stretch forming die, and completely stretching and fitting the skin blank and the skin stretch forming die surface.

6. The skin stretch-forming method of claim 5, wherein in step one, the angle of lifting of the stretch-forming machine jaw is 5 ° ~ 15 °.

7. The skin stretch-forming method of claim 5, wherein: in the first step, the highest part of the arc bulge chord height of the end of the skin blank is contacted with the deepest part of the jaw throat of the stretch-forming machine.

8. The skin stretch-forming method of claim 5, wherein: in the step one, the bending radius of the jaw of the stretch-forming machine is the same as the radius of the end surface of the skin stretch-forming die in the stretching movement direction of the jaw of the stretch-forming machine.

9. The skin stretch-forming method of claim 5, wherein: in the second step, the warping chord height of the skin blank is 50 multiplied by the theoretical thickness of the skin blank +/-15%.

10. The skin stretch-forming method of claim 5, wherein the theoretical thickness of the skin blank is 1mm ~ 2 mm.

Technical Field

The invention relates to an aviation sheet metal part and a forming method thereof, and belongs to the technical field of aviation manufacturing.

Background

The skin stretch forming technology of the airplane is a technology for forming a sheet metal part of the airplane, has the technical advantage of small part forming resilience compared with other sheet metal forming technologies, is particularly suitable for forming large-scale multi-dimensional curvature skin parts, and is widely applied to the aerospace industry. However, because the outer shapes and the radians of the skins in different parts are not consistent, when the skin part with complex variable curvature is subjected to stretch forming, in order to ensure that the skin material is not broken and the generation of the outer surface slip line is reduced as much as possible, the problem that the outer shapes and the radians do not meet the requirements of engineering drawings after the skins are formed often exists, the acceptance of the skins is influenced, and the problem of assembly stress caused by poor conformity of the outer shapes and the radians seriously influences the flight safety of the airplane.

Traditional covering blank is simple rectangle or square structure, and this kind of covering blank structure is unfavorable for each position of covering to obtain comparatively even deflection at stretch-forming process, especially when the appearance radian change of the different positions of covering is comparatively obvious, and this kind of covering plastic deformation's inhomogeneity is more showing, very easily leads to covering local area to appear defects such as slide line and crackle because of the plastic deformation volume is great, and covering local area appearance radian is unqualified.

Therefore, the technical problem to be solved by the invention is how to start from the skin blank structural form, improve the skin stretch forming process method based on the optimized skin blank structural form, improve the radian conformity of the skin after stretch forming, avoid the generation of stretch forming defects, and meet the requirements of engineering drawings so as to realize more excellent aerodynamic appearance of the airplane.

Disclosure of Invention

The invention aims to solve the problems existing in the center of the prior art and provides a skin blank structure of a large airplane, which optimizes the structural form of the skin blank structure.

In order to achieve the purpose, the invention adopts the following technical scheme: the end of the skin blank has a structure protruding outwards in the stretching direction.

Preferably, the structure protruding to the outside is a circular arc protrusion.

Preferably, the maximum chord height of the circular arc bulge of the skin blank is 3 percent ~ 5 percent of the maximum throat depth of the jaw of the stretch-forming machine.

Preferably, the highest part of the arc convex chord height of the skin blank and the maximum part of the skin profile radian are positioned on the same straight line parallel to the stretching movement direction of the jaw of the stretch forming machine.

The invention also aims to provide a skin stretch forming method for improving the radian conformity of the appearance of the skin after stretch forming, avoiding the generation of stretch forming defects, meeting the requirements of engineering drawings and realizing more excellent aerodynamic appearance of the airplane.

In order to achieve the purpose, the invention adopts the following technical scheme: a skin stretch forming method is provided, wherein the skin is the skin blank structure, and the method comprises the following steps:

the method comprises the following steps: lifting the jaw of the stretch-forming machine by a certain angle and bending, and clamping two ends of the skin blank in the jaw of the stretch-forming machine;

step two: making the jaw of the stretch-forming machine move oppositely in the horizontal direction to warp the skin blank;

step three: reducing the height of a jaw of the stretch-forming machine, and contacting the skin blank with the skin stretch-forming die surface;

step four: and (3) stretching the jaw of the stretch forming machine in the horizontal direction towards the direction far away from the skin stretch forming die, and completely stretching and fitting the skin blank and the skin stretch forming die surface.

Preferably, in step one, the angle of lifting the jaws of the stretch-forming machine is 5 ° ~ 15 °.

Preferably, in the step one, the highest part of the arc bulge chord height of the end of the skin blank is contacted with the deepest part of the jaw throat of the stretch-forming machine.

Preferably, in the step one, the bending radius of the jaw of the stretch-forming machine is the same as the radius of the end profile of the skin stretch-forming die in the stretching movement direction of the jaw of the stretch-forming machine.

Preferably, in the second step, the warp chord height of the skin blank is 50 multiplied by the theoretical thickness of the skin blank +/-15%.

Preferably, the theoretical thickness of the skin blank is 1mm ~ 2 mm.

The principle is as follows: based on the analysis and judgment of the shape radian of the skin stretch forming die surface, the part with the largest shape radian on the surface of the skin stretch forming die is found, the length of the skin blank is increased along the stretch forming direction aiming at the part, and then the skin blank is designed into a structure form that the end head has an outward arc bulge so that the part with the largest shape radian of the skin stretch forming die can obtain larger stretching amount. Meanwhile, in the stretch forming process, the jaw of the stretch forming machine moves oppositely in the horizontal direction to warp the skin blank, so that more raw materials of the skin blank move and accumulate to the part with the largest shape radian on the surface of the skin stretch forming die, and then the stretching process is carried out, so that the skin blank is more ensured to be attached to the surface of the part with the largest shape radian on the skin stretch forming die, and the skin with a high-quality shape is obtained.

Compared with the prior art, the invention has the following advantages: starting from the skin blank structural form, the skin blank structural form is optimized, the skin stretch forming uniformity is improved, the defects that the skin generates slip lines, cracks and the like in a local area are overcome, the radian conformity of the appearance of the skin after stretch forming is improved, the skin meets the requirements of engineering drawings, the quality of the skin is further improved, and the more excellent aerodynamic appearance of the airplane is realized.

Drawings

FIG. 1 is a schematic illustration of a skin blank construction in an embodiment of the invention;

FIG. 2 is a schematic diagram of a step one configuration in an embodiment of the present invention;

FIG. 3 is a schematic structural diagram of step two in the embodiment of the present invention;

FIG. 4 is a schematic structural diagram of step three in the embodiment of the present invention;

FIG. 5 is a block diagram illustrating a fourth step in an embodiment of the present invention;

in the figure, 1, a skin blank; 2. the circular arc protruding structure of the end of the skin blank; 3. the circular arc protruding structure of the end of the skin blank; 4. the maximum chord height L of the arc bulge at the end; 5. the maximum chord height L of the arc bulge at the end; 6. a stretching direction; 7. covering a skin drawing die; 8. a jaw of a stretch-forming machine; 9. a jaw of a stretch-forming machine; 10. the maximum radian part of the profile of the skin surface; 11. the highest part of the chord height of the circular arc bulge at the end of the skin blank; 12. the highest part of the chord height of the circular arc bulge at the end of the skin blank; 13. the lifting angle of the jaw of the drawing machine; 14. the lifting angle of the jaw of the drawing machine; 15. Bending radius of a jaw of the stretch-forming machine; 16. warping the skin blank; 17. the maximum chord height H of the skin blank in warping; 18. the jaws of the stretch-forming machine move in opposite directions; 19. The jaws of the stretch-forming machine move in opposite directions; 20. the jaw of the stretch-forming machine moves downwards; 21. the jaw of the stretch-forming machine moves downwards; 22. the direction of stretching movement of the jaw of the stretch-forming machine; 23. the stretching direction of the jaw of the stretch-forming machine.

Detailed Description

The invention is described in further detail below with reference to the accompanying figures 1-5: a large aircraft skin blank structure and a skin stretch-forming method are provided, wherein technical equipment used for stretch-forming at least comprises a stretch-forming machine jaw 9 and a skin stretch-forming die 7, and the end of a skin blank 1 in the stretching direction is provided with a structure protruding outwards in an arc shape.

As shown in fig. 1-2, in order to adapt to the features of the shape radian of the surfaces of different skin stretch formers 7, a skin blank 1 is designed such that one end or two ends in the stretching direction 6 have structures protruding outward in an arc, so as to ensure that the surfaces of the skin blank 1 and the skin stretch formers 7 have the optimal fit degree, in this embodiment, two opposite ends of the skin blank 1 have structures protruding outward in an arc, namely a skin blank end arc protruding structure 2 and a skin blank end arc protruding structure 3, and simultaneously, in order to ensure that the stretch forming process of the skin blank 1 is more uniform and meet the requirement of clamping the skin blank 1, the maximum chord height L4 of the end arc protrusion of the skin blank 1 and the maximum chord height L5 of the end arc protrusion are 3% of the maximum throat depth of the stretch formers 8 and the jaws 9, and ~ 5% of the maximum throat depth of the stretch formers 9, and further, in order to make the stretch amounts of the different areas of the skin blank 1 substantially the same, the stretch amount of the surface radian maximum arc 10 of the skin blank 10 is increased, and the defects of the skin blank 10 are avoided in the same direction as the maximum stretch line of the skin blank.

The skin stretch-forming method, as shown in fig. 2-5, includes the following steps:

the method comprises the following steps: lifting the jaw 8 of the stretch-forming machine and the jaw 9 of the stretch-forming machine for a certain angle and bending, and clamping the two ends of the skin blank 1 in the jaw of the stretch-forming machine;

step two: moving the jaw 8 of the stretch forming machine and the jaw 9 of the stretch forming machine in the horizontal direction oppositely to warp the skin blank 1;

step three: reducing the heights of the jaw 8 and the jaw 9 of the stretch-forming machine, and making the surface of the skin blank 1 contact with the surface of the skin stretch-forming die 7;

step four: and stretching the jaws 8 and 9 of the stretch forming machine in the horizontal direction towards the direction far away from the skin stretch forming die 7, and completely stretching and jointing the surface of the skin blank 1 and the skin stretch forming die 7. Therefore, the stretching amount of each part of the skin can be ensured to be uniform, and the defects of cracks, sliding lines and the like in a local area are avoided.

In step one of the embodiment, in order to ensure that the largest possible clamping area of the two ends of the skin blank 1 is obtained, the stretching machine jaws 8 and 9 are lifted, and the lifting angles 13 and 14 of the stretching machine jaws are 5 degrees and ~ 15 degrees respectively.

In the first step of this embodiment, in order to improve the conformity between the surface of the skin blank 1 and the surface of the skin stretch-forming die 7 after stretch-forming, the jaw 8 of the stretch-forming machine and the jaw 9 of the stretch-forming machine are bent, and the bending radius 15 of the jaw of the stretch-forming machine is the same as the radius of the surface of the end of the skin stretch-forming die 7 in the stretching direction 6 of the jaw 8 of the stretch-forming machine and the jaw 9 of the stretch-forming machine.

In the first step of this embodiment, the two ends of the skin blank 1 are clamped in the jaws 8 and 9 of the stretch-forming machine, and the highest part 11 of the arc protrusion chord height of the end of the skin blank 1 and the highest part 12 of the arc protrusion chord height of the end of the skin blank are in contact with the jaws 8 and 9 of the stretch-forming machine at the deepest throat to ensure that the skin blank 1 is firmly clamped in the jaws 8 and 9 of the stretch-forming machine.

In step two of this embodiment, after the clamping is completed, the stretch former jaw 8 and the stretch former jaw 9 are moved in opposite directions in the horizontal direction, the moving directions are as shown in fig. 3, the stretch former jaw opposite moving direction 18 and the stretch former jaw opposite moving direction 19 warp the skin blank 1, and the maximum chord height H17 of the skin blank warp 16 is 50 × the theoretical thickness ± 15% of the skin blank 1.

Next, the stretching machine jaw 8 and the stretching machine jaw 9 are moved downward, the moving directions are shown in fig. 4, the stretching machine jaw moves downward 20 and the stretching machine jaw moves downward 21, and the skin blank 1 is brought into surface contact with the skin stretching die 7, that is, step three in the present embodiment.

And finally, stretching the skin blank 1 and the skin stretching die 7 in the stretching movement direction 22 and the stretching movement direction 23 of the jaws of the stretch forming machine, namely completely stretching and jointing the skin blank 1 and the skin stretching die 7, namely in the fourth step in the embodiment, wherein the stretching movement is carried out on the jaws 8 and 9 of the stretch forming machine in the horizontal direction towards the direction away from the skin stretching die 7. Therefore, the stretching amount of each part of the skin can be ensured to be uniform, and the defects of cracks, sliding lines and the like in a local area are avoided.

In the present invention, the theoretical thickness of the skin blank 1 is 1mm ~ 2mm, but the thickness is not limited to this range, and other thickness ranges may be applied.

The above examples are merely preferred embodiments of the present invention and are not to be construed as limiting the invention. The structure of the skin blank is not limited to the structure described in the above embodiments, and may be modified accordingly according to actual conditions. It will be appreciated by those skilled in the art that changes may be made in this embodiment without departing from the principles of the invention.