Method of producing bicurved surface shells (versions)

FIELD: process engineering.

SUBSTANCE: set of invention relates to metal forming and may be used in producing bicurved surface shells. Separate parts are preformed. Here, to compensate for welding strains from welding seam shrinkage, parts made from titanium or steel are produced with undercurved edge while parts from aluminium are made with fluted edges all over their edges in the zone of post-welding deformation with width making 8-10 S where S is part thickness.

EFFECT: higher quality of bicurved surface shells.

8 cl, 6 dwg

 

The invention relates to the manufacture of large shell structures that can be assembled from separate stamped parts (petals and bottoms), welded and Equatorial and meridional sutures, and can be used in various industries in the manufacture of shells of double curvature.

There are various ways of making forged and welded structures made of individual parts that are pre-deformed by forging equipment by the method of successive local and rotary-local formation with the use of machinery and versatile specialized equipment. To obtain structures of complex shapes or large, when it is impossible to make a design from one blank is used, the method of dividing the casing into separate elements, and then from a separate pre-formed elements welded single shell design, see, for example, Vlasenko, Avigation, Weedin and other "manufacturing Technology of submarines" C. Saint-Petersburg, 2006, p.63, RIS, which is taken as a prototype, and forming of sheet parts can be executed in one of the known methods described, for example, in the patents of the Russian Federation No. 21294588, 2243843, 2243844, 2323795.

As analogues of this method can be mentioned methods of manufacturing sferic the ski Moss-type tanks, used for gas carrier ships, and a method of manufacturing welding products for submarine and surface ship-building, which is selected as a prototype (see Antoshkin "Technology of forming large parts". M., engineering, 1973, p.9, Fig.2).

The selected prototype is a method of manufacturing a spherical structure, which is divided into separate parts, roll forming all parts of the local deformation of the sheet blanks, after which the parts will be welded to each other in a spherical structure.

The disadvantage of this method is that the parts are made on theoretical size and shape without regard to welding deformation. After welding is shrinkage of welds in both longitudinal and transverse directions, so this design differs from the specified nominal dimensions. Regularities of welding deformations caused by increased requirements to the shape of the surface of the membranes after welding and to the carrying capacity of joints in structures. When welding membranes value movements in place of the suture after the first pass is 1-5 mm, depending on the hardness of the welded shell. In addition, it was found that even small geometrical deviations of joined edges cause a noticeable decrease in strength.

The technical result achieved by the invention is in reducing the impact of welding deformations on the specified form during welding of the individual parts of the shell.

This technical result is achieved in the following way. The proposed method previously conducted forming separate parts, in which to compensate for welding deformation of the shrinkage of the welded joints of parts made of steel or titanium is made with nedogibi edges from their theoretical form, and aluminum parts with bend the edges around the perimeter of the parts in the area of the subsequent welding deformations with a width equal to 8-10 S, where S is the thickness of the details. Pre-forming of sheet parts carry on forging equipment using universal snap the method of successive local presses or rotary-local method on the reference deforming element with the subsequent connection of the bent parts into a single structure mainly by welding. Edge parts of the steel and titanium alloy comply with nedogibi and aluminium alloys - with the curve, because at first because of their low thermal conductivity when welding the way who are the so-called "houses", and the second is due to their high thermal conductivity when welding, a so-called "failures". Butt-and-groove edges of side lobes, joined with the bottom, also made with nedogibi (break). These defects caused by residual welding deformations of the shrinkage of welds and deflection of the abutting edges of the workpieces, are compensated by pre-neogia for some parts and bend to the other.

In the particular case to eliminate residual displacements and stresses of the welded edges of the parts of the weld joint area pre-roll. In this case, the area of the shell in the place of the future of a welded joint is moved (nedohin/break) at a value of 0.5 S, which numerically can be equal axial or radial movement in the zone of the weld. The surface profile of the edge is a mirror image of the profile of the shell after welding. In this case, the welding deformation of the bending edge of the shell to compensate for the deformed zone and residual displacement will be close to zero. To compensate for the longitudinal welding deformation 3/4 middle part of the edges of the petals pre-roll roller, which create pressure calculated by the empirical formula:

,

where b is the width of the rollers, d is the diameter of the rollers, s - tol is in the shell, σTE - the yield strength and the modulus of elasticity of rolled material.

In another particular case details - the bottoms are made higher by the amount of transverse shrinkage of the weld and its vertical displacement, and the edge of the bottom perimeter thermoabrasion with inflection (nedogibi) depending on the material by an amount equal to 1/2 the difference between the nominal and theoretical diameters of the bottom. In the known solutions the elimination of the vertical component in the weld seam area on the shell can be produced by the introduction of the allowance.

In another particular case, the welding is performed with the inner concave side of the shell from the middle of the edge to its ends.

Observed patterns and the proposed method were tested in the framework of development work (R & d "Shelf") and on the order Triton-NN.

The essence of the method of forming sheet metal structures with dual curvature of the surface is illustrated by the attached drawings:

figure 1 - General view of the torispherical heads with a double curvature surface;

figure 2 - most convex Central dome torispherical heads;

figure 3 - lateral petal torispherical heads;

figure 4 - cross section a-a figure 3;

figure 5 - estimated computer determination of the expected deformation when welding petals;

6 - settlement computer is characteristic determination of the expected deformation during welding of the bottom and the annular zone, consisting of welded petals.

In the drawings, the following notation: s is the thickness of the stamped part, h is the depth of stamping bottom, D - base diameter, d is the seam allowance around the perimeter of stamping bottom.

The greatest thinning arising in detail during the deformation, have approximately the same value. The magnitude of thinning sheet structural elements and the boundary values of the deformation is determined depending on the dimensions of the workpieces and the relative radii of a given curvature, and grade stamping material.

In this case, as shown by recent studies, in particular for OCD "Shelf"that runs under the Federal target program (FTP) "national technological base" for 2007-2011, geometry and thinning blanks were within the specified tolerances on the design.

The most convex part of the welded plate structures produced by deformation, in this example, the Central spherical dome (figure 1, item 1 - bottom), provided with nedogibi joined by edges to the magnitude of its subsequent transverse shrinkage in the weld (figure 2, 3), which is determined through calculation OCT-93 and on the basis of experience of manufacturing similar designs.

As shown by calculations, performed using the software package ANSYS (figure 5 and 6), and experience manufacture the Oia similar designs, welding should be implemented initially on the inner side, i.e. on the concave part, and a welding lead from the middle of the edge to its ends, which reduces the overall shrinkage of the structure.

In view of the above the main provisions in the manufacture of such sheet torispherical design was produced at JSC "Severnaya Verf" under the order "Triton-NN. Shaping the bottom R=2000 mm, thickness t=10 mm alloy 1561 tolerance ΔR=4 mm (control template) and six torispherical petals thickness t=10 mm with a tolerance of thickness Δ=3 mm at each joint was carried out on the press "Clear" with the capacity of 2500 kN. Thus, it was possible to obtain the required quality flexible, acceptable deviations shapes and sizes, allowing the collected construction successfully pass testing.

1. A method of manufacturing shells with double curvature surface of a separate pre-formoobrazovanii parts, made of steel or titanium, consisting of bottoms and petals, welded Equatorial and meridional sutures, characterized in that the individual parts thermoabrasion with nedogibi edges from their theoretical forms around the perimeter of the parts in the area with a width equal to 8-10 S, where S is the thickness of the details.

2. The method according to claim 1, characterized in that when forming the bottoms of their produce is velichenko height on the amount of transverse shrinkage of the weld, and the edge of the bottom perimeter thermoabrasion to bend by an amount equal to 1/2 the difference between the nominal and theoretical diameters of the bottom.

3. The method according to claim 1, characterized in that 3/4 of the middle part of the edges of the petals pre-roll roller, which create pressure calculated by the formula
where
b - the width of the rollers, d is the diameter of the rollers, s - thickness of the membrane, σTE - the yield strength and the modulus of elasticity of rolled material.

4. The method according to claim 1, characterized in that the welding is performed with the inner concave side of the shell from the middle of the edge to its ends.

5. A method of manufacturing shells with double curvature surface of a separate pre-formoobrazovanii parts, made of aluminum, consisting of bottoms and petals, welded Equatorial and meridional sutures, characterized in that the individual parts thermoabrasion with crimped edges from their theoretical forms around the perimeter of the parts in the area with a width equal to 8-10 S, where S is the thickness of the details.

6. The method according to claim 3, characterized in that when forming the bottoms they are made to bend by an amount equal to 1/2 the difference between the nominal and theoretical diameters of the bottom.

7. The method according to claim 3, characterized in that 3/4 of the middle part of the edges of the petals pre-p is roll roller, which create pressure calculated by the formula
where
b - the width of the rollers, d is the diameter of the rollers, s - thickness of the membrane, σTE - the yield strength and the modulus of elasticity of rolled material.

8. The method according to claim 3, characterized in that the welding is performed with the inner concave side of the shell from the middle of the edge to its ends.



 

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