METHOD FOR FORMING LARGE-SIZE CURVED THIN-WALLED METAL SKIN

Abstract

A method for forming a large-size curved thin-walled metal skin is disclosed, wherein the position and size characteristics of stiffeners on a curved panel is extracted; the thickness of the curved panel and the thin-walled skin after assembly is assumed to be m, and a forming surface of the punch is offset outwards along a normal line by the thickness m to obtain the characteristics of the inner surface of a female die; the number of the discrete support moulds is set to be the same as the number n of the stiffeners based on the size and distribution of the stiffeners on the curved panel; and the punch and the female die combined with the discrete support moulds are used to carry out stamping of a curved thin-walled slab to obtain a required thin-walled skin component.

Claims

1. A method for forming a large-size curved thin-walled metal skin, comprising the following steps: step 1: extracting the position and size characteristics of stiffeners on a curved panel according to the assembly relationship between the curved panel and a thin-walled skin; step 2: assuming that the thickness of the curved panel and the thin-walled skin after assembly is m, determining the size of a forming punch based on the shape and size of the curved panel, and offsetting a forming surface of the punch outwards along a normal line by the thickness m based on the size of the forming surface to obtain the characteristics of the inner surface of a female die; step 3: determining the size of discrete support moulds to be the same as that of the curved panel according to the thickness of the curved panel, and determining forming surfaces of the discrete support moulds based on the inner surface of the forming thin-walled skin; step 4: setting the number of the discrete support moulds to be the same as the number n of the stiffeners based on the size and distribution of the stiffeners on the curved panel, and the positions of the discrete support moulds on the punch are consistent with the positions of the stiffeners on the curved panel; step 5: processing and manufacturing the punch, the female die and n discrete support moulds according to step 2 and step 3; step 6: fixing the n discrete support moulds on the punch according to step 4, and the relevant positions for connecting the discrete support moulds are corresponding to the positions of the stiffeners on the curved panel during assembly; and step 7: using the punch and the female die combined with the discrete support moulds to carry out stamping of a curved thin-walled slab to obtain a required thin-walled skin component.

Description

DESCRIPTION OF DRAWINGS

[0024] FIG. 1(a) is a schematic diagram of a curved panel.

[0025] FIG. 1(b) is a schematic diagram of a thin-walled skin.

[0026] FIG. 2 is a schematic diagram of stamping of a curved panel.

[0027] FIG. 3 is a schematic diagram of forming a large-size curved thin-walled skin by a discrete support mould;

[0028] FIG. 4 is a schematic diagram of assembly of a discrete support mould and a curved panel forming punch;

[0029] FIG. 5 is a schematic diagram of action of a discrete support mould on a thin-walled skin.

[0030] In the figures: 1 curved panel; 2 thin-walled skin; 3 punch; 4 female die; 5 connecting bolt; 6 discrete support mould.

DETAILED DESCRIPTION

[0031] The technical solution of the present invention is further described below in combination with the drawings and specific embodiments.

Embodiment 1

[0032] Referring to FIG. 3 for description, a method for forming a large-size curved thin-walled metal skin, comprising the following steps:

[0033] Step 1: extracting the position and size characteristics of stiffeners on a curved panel according to the assembly relationship between the curved panel and a thin-walled skin;

[0034] Step 2: assuming that the thickness of the curved panel and the thin-walled skin after assembly is m, determining the size of a forming punch based on the shape and size of the curved panel, and offsetting a forming surface of the punch outwards along a normal line by the thickness m based on the size of the forming surface to obtain the characteristics of the inner surface of a female die;

[0035] Step 3: determining the size of discrete support moulds to be the same as that of the curved panel according to the thickness of the curved panel, and determining forming surfaces of the discrete support moulds based on the inner surface of the forming thin-walled skin;

[0036] Step 4: setting the number of the discrete support moulds to be the same as the number n of the stiffeners based on the size and distribution of the stiffeners on the curved panel, and the positions of the discrete support moulds on the punch are consistent with the positions of the stiffeners on the curved panel;

[0037] Step 5: processing and manufacturing the punch, the female die and n discrete support moulds according to step 2 and step 3;

[0038] Step 6: fixing the n discrete support moulds on the punch according to step 4, and the relevant positions for connecting the discrete support moulds are corresponding to the positions of the stiffeners on the curved panel during assembly; and

[0039] Step 7: using the punch and the female die combined with the discrete support moulds to carry out stamping of a curved thin-walled slab to obtain a required thin-walled skin component.

[0040] The n discrete support moulds used are combined with the curved panel forming punch, then the stamping of the thin-walled skin is carried out, and the positions of the discrete support moulds are consistent with the positions of the stiffeners on the curved panel, so that it can be ensured that the part of the thin-walled skin corresponding to the stiffeners obtains sufficiently high shape and dimensional accuracy, thereby realizing the subsequent reliable connection of the thin-walled skin and the curved panel.

Embodiment 2

[0041] Referring to FIG. 4 for description, a method for forming a large-size curved thin-walled metal skin, comprising the following steps:

[0042] In step 6, the n discrete support moulds are dispersedly arranged on the punch, the dispersing positions of discrete support moulds can be determined according to the positions of the stiffeners on the curved panel, the replacement stiffeners of the discrete support moulds are distributed on the punch, and the dispersing positions of the discrete support moulds can also be adjusted according to the forming condition of the thin-walled slab after forming. Other steps are the same as those in embodiment 1.

[0043] When a sheet is formed by a solid die, due to the uneven load distribution and different contact states on various parts of a slab, the problems of wrinkling and warping are prone to occur during forming; whereas a certain distance exists among the discrete support moulds, so that the problems such as wrinkling and warping which may occur during a forming process can be easily eliminated by adjusting the positions of the discrete support moulds on the punch. The discrete support moulds are assembled and connected with the punch, so that the discrete support moulds are easy to replace, and can be replaced by different discrete support moulds to be used for forming thin-walled skins of different thicknesses, which saves the material and processing cost of the moulds.

Embodiment 3

[0044] Referring to FIG. 5 for description, a method for forming a large-size curved thin-walled metal skin, comprising the following steps:

[0045] In step 6, the discrete support moulds and the punch can be effectively connected by bolts, and each discrete support mould is composed of a plurality of small moulds with surface shape and size requirements. Each discrete support mould used in other steps is composed of a plurality of small mould blocks, and a gap exists among adjacent small mould blocks. Other steps are the same as those in embodiment 1.

[0046] In a traditional stamping process, most of the moulds are in a solid form, which are prone to have excessive local contact stress and redundant deformation. The discrete support moulds composed of a plurality of small mould blocks are only in partial contact with the thin-walled slab, so that the areas on the thin-walled skin that do not need to be assembled with the stiffeners are all in a relatively free state, which can avoid unreasonable, uncontrollable or redundant deformation in such areas when a solid punch is used for forming.