CN103577650A - Thin-plate large oil tank welding predeformation forming method - Google Patents

Abstract

The invention relates to a thin-plate large oil tank welding predeformation forming method which solves the problems that in the prior art, a welded thin-plate large oil tank welding deformation is large, and quality is not easy to control. The method comprises the steps of calculating according to known conditions to obtain deformation after welding, designing preset predeformation of the size of the oil tank before welding according to the deformation obtained through calculation so as to obtain the actual production size of the oil tank before welding and enable the oil tank to meet the requirements of designed sizes after welding. According to the preset deformation before welding, lower-case delta is equal to upper-case delta Ltg theta in the vertical direction and the horizontal direction, wherein the theta is an included angle between residue stress of any point after welding and the component of F1 in the vertical direction, R is a circular arc welding joint radius, N is the rigidity of the oil tank, and S is the section area of a welding joint and includes the area of a heat influencing area. The method provides a specific formula, is accurate in numerical calculation, and can save a large amount of cost and a large amount of time for designing tools, especially for products which are large in size and large in number of welding joints.

Description

The large-scale fuel tank welding anti-distortion of thin plate forming method

Technical field:

The present invention relates to a kind of welding method of fuel tank, particularly the large-scale fuel tank welding anti-distortion of a kind of thin plate forming method.

Background technology:

For the large-scale fuel tank of the thin plate with the long weld seam of circular arc, because its shape is comparatively complicated, sheet material is thin, complex structure, and welding capacity is large, and fusion length is long, and distortion is large, is the difficult point during welding is produced all the time.After welding, entire length size is past more much smaller than Design Requirement Drawing size, and the radius of welding rear fuel tank arc is also little than the radius of designing requirement.So this kind of fuel tank exists the problem of qualification rate extremely low (almost completely unqualified) always! Have a strong impact on the quality of product.The measure that prevents post welding distortion that current this kind of fuel tank taked has: the methods such as welding procedure are proofreaied and correct, changed to rigid fixation welding, postwelding.These methods can only change 1-2mm by the size of postwelding.Can not meet the designing requirement of product far away.

Summary of the invention:

The present invention, by a kind of welding method of reversible deformation is provided, has solved the large-scale fuel tank welding deformation amount of employing prior art welding thin plate large, and quality is not allowed manageable problem.

The present invention is realized by following technical scheme:

A large-scale fuel tank welding anti-distortion forming method, comprises the following steps:

According to known conditions, calculate the deflection of postwelding, according to the deflection calculating, to the size of fuel tank, the default anti-deformation before welding designs, draw the actual production size of fuel tank before welding, make the fuel tank size that meets design requirement after welding, before weldering, the concrete computation process of default deflection is:

The in the situation that of welding fuel tank when not establishing welding anti-distortion amount, carry out following calculating:

Fuel tank circular arc weld seam is in certain suffered moment a bit:

DM=F1 * Rsin θ cos θ, wherein F1 is size and the distribution arrangement of any point postwelding unrelieved stress on circular arc weld seam, and θ is the angle of F1 and F1 vertical direction component F 2, and R is circular arc weld seam radius, the known fuel tank one side Moment of quadraturing:

wherein θ 1 is the F1 of fuel tank circular arc weld seam left and right end points and the angle value of F2,

angle value for F1 and the F2 on fuel tank circular arc weld seam summit;

The whole Moment of fuel tank:

Fuel tank being deformed in the vertical direction:

$\mathrm{\ΔL}=2F1\×R{\∫}_{\mathrm{\θ}1}^{\frac{\mathrm{\π}}{2}}\sin \mathrm{\θ}\cos \mathrm{\θd\θ}/N$

In above formula, the integral rigidity that N is fuel tank

F1=σ 2 * S, wherein σ 2 is weld residual stress value, depends on welding rod material, can table look-up and draw from metal material handbook, the sectional area that S is weld seam, comprises the area of heat-affected zone;

Fuel tank being deformed in the horizontal direction:

In this formula of δ=△ Ltg θ, δ value is approximate treatment value, need slightly revise according to production reality;

The △ L more than calculating and δ (horizontal direction left end deflection δ 1 and right-hand member deflection δ 2), as reversible deformation value that should be default, design actual production figure and other relevant size according to these two values by graphing method.

The present invention provides clear and definite formula, eliminates the impact of welding deformation with reversible deformation, and numerical evaluation is accurate, and cost is low, especially large to physical dimension, and the product that commissure number is many can be saved a large amount of expense and time of designing frocks.

Accompanying drawing explanation:

Fig. 1 is fuel tank welding residual stress distribution situation figure when not taking reversible deformation;

Fig. 2 is reserved reversible deformation rear fuel tank Production design figure.

Embodiment:

For the welding of the large-scale fuel tank of thin plate with the long weld seam of circular arc, due to the contraction of weld seam, make along the bead direction welding residual stress that distributing.Its distribution situation is as shown in Figure 1: solid line is the profile of fuel tank requirement, and size L2 is the size of fuel tank requirement; Dotted line is to produce the profile after distortion after fuel tank welding, size L1 is the size after fuel tank distortion, δ 1, δ 2 are respectively the size that the left side and the right dwindle, f is that fuel tank produces the amount of deflection producing after distortion, power F1 is size and the distribution arrangement (along circular arc tangential line direction) of postwelding unrelieved stress, and power F2 is that power F1 is the component perpendicular to arm of force L direction (being the vertical component of F1).Dash area represents power F2 size distribution situation.R is the radius of arc, and θ is the angle of F1 and F2.Δ L is fuel tank vertical direction deflection.

By upper figure, can be found out, fuel tank is in certain suffered moment a bit:

dM=F2×L---(1)

L=R×cosθ---(2)

F2=F1×sinθ---(3)

By (1), (2), (3), can be obtained:

dM=F1×Rsinθcosθ，

Quadrature known:

$M=F1\×R{\∫}_{\mathrm{\θ}1}^{\frac{\mathrm{\π}}{2}}\sin \mathrm{\θ}\cos \mathrm{\θd\θ}$ θ 1 is the F1 of fuel tank circular arc weld seam left and right end points and the angle value of F2,

angle value for F1 and the F2 on fuel tank circular arc weld seam summit;

The whole Moment of fuel tank:

If the whole rigidity of fuel tank is N,

Fuel tank in the vertical direction whole deformation distance be:

$\mathrm{\ΔL}=2F1\×R{\∫}_{\mathrm{\θ}1}^{\frac{\mathrm{\π}}{2}}\sin \mathrm{\θ}\cos \mathrm{\θd\θ}/N$

In above formula, F1=σ 2 * S, wherein σ 2 is weld residual stress value, depends on welding rod material, can table look-up and draw from metal material handbook, the sectional area that S is weld seam, comprises the area of heat-affected zone;

Fuel tank being deformed in the horizontal direction:

In this formula of δ=△ Ltg θ, δ value is approximate treatment value, need slightly revise according to production reality;

The △ L more than calculating and δ (horizontal direction left end deflection δ 1 and right-hand member deflection δ 2), as reversible deformation value that should be default, design actual production figure and other relevant size according to these two values by graphing method.

Fig. 2 is reserved reversible deformation rear fuel tank Production design figure, and wherein dotted line is for reserving the profile after reversible deformation, and size L1 is the size after reversible deformation; Solid line is the profile of designing requirement, and size L2 is the size requiring, and δ 1, δ 2 are respectively the size that the left side and the right increase, and △ L is reversible deformation reserved size in the vertical direction.

Claims (1)

1. the large-scale fuel tank welding anti-distortion of a thin plate forming method, is characterized in that: comprise the following steps:

According to known conditions, calculate the deflection of postwelding, according to the deflection calculating, to the size of fuel tank, the default anti-deformation before welding designs, draw the actual production size of fuel tank before welding, make the fuel tank size that meets design requirement after welding, before weldering, the concrete computation process of default deflection is:

The in the situation that of welding fuel tank when not establishing welding anti-distortion amount, carry out following calculating:

Fuel tank circular arc weld seam is in certain suffered moment a bit:

DM=F1 * Rsin θ cos θ, wherein F1 is size and the distribution arrangement of any point postwelding unrelieved stress on circular arc weld seam, and θ is the angle of F1 and F1 vertical direction component F 2, and R is circular arc weld seam radius, the known fuel tank one side Moment of quadraturing:

wherein θ 1 is the F1 of fuel tank circular arc weld seam left and right end points and the angle value of F2,

angle value for F1 and the F2 on fuel tank circular arc weld seam summit;

The whole Moment of fuel tank:

Fuel tank being deformed in the vertical direction:

$\mathrm{\ΔL}=2F1\×R{\∫}_{\mathrm{\θ}1}^{\frac{\mathrm{\π}}{2}}\sin \mathrm{\θ}\cos \mathrm{\θd\θ}/N$

In above formula, the integral rigidity that N is fuel tank;

F1=σ 2 * S, wherein σ 2 is weld residual stress value, depends on welding rod material, can table look-up and draw from metal material handbook, the sectional area that S is weld seam, comprises the area of heat-affected zone;

Fuel tank being deformed in the horizontal direction:

In this formula of δ=△ Ltg θ, δ value is approximate treatment value, need slightly revise according to production reality;

The △ L more than calculating and δ (horizontal direction left end deflection δ 1 and right-hand member variable δ 2), as reversible deformation value that should be default, design actual production figure and other relevant size according to these two values by graphing method.

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