CN104942113B - Laser assembly solder plate drawing process weld movement method for quick predicting - Google Patents

Abstract

The invention discloses a kind of laser assembly solder plate drawing process weld movement method for quick predicting, comprise 1) by discrete workpiece for triangular element, formation of parts grid, sets up virtual work equation to the final configuration of plate; 2) set up the finite element equation of a step simulation; 3) adopt the newton-Laplce method with convergence factor, set up iterative equation; 4) solve this iterative equation; Obtain a Nonlinear System of Equations, adopt the newton-Laplce method with convergence factor, set up second iterative equation; Solve second iterative equation, obtain initial displacement field; Then forward the 3rd to) step is the tailor welded grid of exportable inverse after newton-Laplce iteration convergence; 5) at the tailor welded grid of formation of parts grid and inverse acquisition, the node of each unit, attachment weld place obtains two space curve l₁And l₂; 6) by two space curve l₁And l₂To X-Y plane projection, obtain two plane curve l ' respectively₁And l '₂; Calculate the side-play amount of weld seam.

Description

Laser assembly solder plate drawing process weld movement method for quick predicting

Technical field

The present invention relates to a kind of weld movement Forecasting Methodology, especially a kind of laser assembly solder plate drawing process weld movement is fastSpeed Forecasting Methodology.

Background technology

In order to reduce the assembly precision of tare, raising vehicle body, the rigidity that increases vehicle body, reduction body of a motor car manufacture processIn punching press and assembly cost, reduce the number of bodywork parts and its integration be very important simultaneously. Thereby, Yi ZhongtongTime overcome traditional separating shaped method and integral forming method shortcoming production form--tailor welded is stamping to grow up. Tailor welded refers to the cold-rolled steel sheet of similar and different thickness, intensity, material, is cut into suitable size and dimension, soRear Laser Welding is connected into a desirable entirety. The commercial this tailor welded of automobile making strikes out specific Assembly of the parts automobile, withMeeting own and consumer improves vehicle product quality, reduces production costs, alleviates car weight, reduces oil consumption, protection of the environment etc.The multiple demand of aspect.

Although the use of tailor welded has brought many benefits, also there are a lot of technical insoluble problems simultaneously,Wherein topmost problem be change by weld metal zone tissue that the forming property that causes declines and weld movement causes cannot be accurateReally by problems such as certain material location: the higher side plate material distortion of intensity is less, and the lower side plate material distortion of intensity is larger,Make weld seam both sides form inhomogeneous deformation. In addition, mechanical process and shaping influence factor that laser assembly solder plate is shaped are very complicated,Be one and integrate geometrical non-linearity, material nonlinearity, the non-linear strong nonlinearity problem in border, especially for comparatively multipleAssorted automobile panel, calculates and expends time in tens hours at least, at most more than one week. If adopt traditional incrementMethod simulation softward needs repeatedly to call execution in optimization design, optimizes the time consuming often because exceeded instituteThe limit that can bear, thereby optimization has lost meaning. Particularly, at the beginning of stamping products design, mould and technique information etc. are largeAmount parameter is undetermined, if adopt this strategy need to consume a large amount of manpowers and time, feasibility is lower.

Inverse analog algorithm is a kind of blank Optimization Design of founding about the nineties in 20th century, but spells for laserThe prediction of welding plate forming process weld movement not yet finds that there is Patents and declares.

Summary of the invention

The object of the invention is for overcoming above-mentioned the deficiencies in the prior art, a kind of laser assembly solder plate drawing process weld seam is providedMobile method for quick predicting.

For achieving the above object, the present invention adopts following technical proposals:

A kind of laser assembly solder plate drawing process weld movement method for quick predicting, comprises the following steps:

1). by discrete workpiece be triangular element, obtain formation of parts grid, set up following to the final configuration of the plate of workpieceVirtual work equation

$W=\mathrm{\Σ}{\∫}_{V_e}{{\mathrm{\δ}}_{\mathrm{\ϵ}}}^T\mathrm{\σ}dV-{\∫}_{A_e}{{\mathrm{\δ}}_u}^{T}FdA=0---\left(1\right)$

δ ε in formula---in unit, the sham of arbitrfary point is moved;

δ u---the virtual strain of arbitrfary point in unit;

σ---cauchy stress;

F---outer force vector;

V_e---volumetric spaces;

A_e---surf zone;

T---represent transposed matrix;

2). set up the finite element equation of a step simulation

k(u)u＝p(u)(2)

K in formula (u)---stiffness matrix;

P (u)---external force load vector;

U---displacement;

3). because formula (1) and formula (2) they are all the functions of displacement components u, therefore formula (2) is a Nonlinear System of Equations, adoptsBy the newton-Laplce method with convergence factor, the difference of supposing external force and internal force is R (u), and its iterative equation is

$\left\{\begin{array}{c}{k}_T\left(u^i\right){\mathrm{\Δu}}^i=R\left(u^i\right)\\ u^{i+1}=u^i+{\mathrm{\ω\Δu}}^i\end{array}\right.---\left(3\right)$

ω in formula---iteration relaxation factor, Δ uⁱ---the displacement increment of i step, R (uⁱ)---the external force internal force of i stepPoor, uⁱ⁺¹---the displacement increment of i+1 step, uⁱ---the displacement increment of i step, k_T---tangent stiffness matrix;

4). in order to solve formula (3), need to provide an initial displacement field, i.e. the initial value of displacement components u; The quality of initial value certainlyDetermine the efficiency that formula (3) solves; Suppose that external force load is zero,

k(u)u＝0(4)

K in formula (u)---stiffness matrix;

U---displacement;

Similarly, obtain a Nonlinear System of Equations, adopt newton-Laplce method with convergence factor, suppose external force and inThe difference of power is R (u), and its iterative equation is

$\left\{\begin{array}{c}{k}_T\left(u^i\right){\mathrm{\Δu}}^i=F_{in}\left(u^i\right)\\ u^{i+1}=u^i+{\mathrm{\ω\Δu}}^i\end{array}\right.---\left(5\right)$

ω in formula---iteration relaxation factor, Δ uⁱ---the displacement increment of i step, F_in(uⁱ)---the internal force of i step, uⁱ⁺¹——The displacement increment of i+1 step, uⁱ---the displacement increment of i step, k_T---tangent stiffness matrix;

Solve this equation group, can obtain initial displacement field u₀; Then forward (3) step to, after newton-Laplce iteration convergenceIt is the tailor welded grid that exportable inverse obtains;

5). in the tailor welded grid two nested grid systems the insides of formation of parts grid and inverse acquisition, each unit, attachment weld placeNode can obtain two space curve l₁And l₂；

6). by two space curve l₁And l₂To X-Y plane projection, obtain two plane curve l ' respectively₁And l '₂; According to formula $\mathrm{\Δ}l=\underset{i=1}{\overset{N-1}{\Σ}}\sqrt{{\left(x_1^i-x_2^i\right)}^2+{\left(y_1^i-y_2^i\right)}^2}$ Calculate the side-play amount of weld seam;

Δ l in formula---weld excursion amount;

N---curve l '₁And l '₂The hop count of on average being divided;

---curve l '₁The abscissa of i point;

---curve l '₁The ordinate of i point;

---curve l '₂The abscissa of i point;

---curve l '₂The ordinate of i point.

Step 4) in for the simple part of some shape matching, such as non-straight wall class part, can by three-dimensional grid directly toX-Y plane projection, thereby obtain the 3rd) the required initial displacement field u of step₀, this type of part requires to after X-Y plane projectionGrid does not overlap.

The present invention only considers the shape of final workpiece, the profile that known parameters is workpiece, the thickness of original blank, unknown parameterThere are the shape of blank and the thickness of workpiece. These parameters can be tried to achieve by minimizing plastic deformation merit. In order to ignore different distortionThe impact in path, has made a series of hypothesis, and wherein two main aspects are: load in proportion; Ignore mould and plateContact boundary condition, and use the friction boundary condition (shown in Fig. 1) of simplification instead. In order to ignore the impact in different distortion path,Make a series of hypothesis:

1. Large Elastic-Plastic Deformation, material is completely incompressible.

2. deformation process is that ratio loads, based on plastic deformation theory.

3. material etc. is to strengthening or anisotropic strengthening.

4. the effect of mould shows as drift normal pressure heterogeneous, the frictional force under drift and blank holder.

The present invention only consider distortion after end-state and initial plate blank, do not consider loading history, the active force of mouldAdopt equivalent external applied load to replace. The frictional resistance that blank holder produces replaces with an equivalent load vector, drift and mouldThe active force of tool replaces with a normal pressure and a tangential friction force.

The present invention proposes a kind of inverse analog method that is applicable to laser assembly solder plate, and the method is because each node only has two freedomDegree, analog rate is very fast, is very suitable for carrying out at the beginning of product and Design of Dies analysis and the optimization of technique. By oppositelyThe line of demarcation of bi-material in the blank of simulation inverse, can instead fast push away various technique in tailor welded part forming processThe situation that affects of weld movement, how this for predicting and control weld movement, takes into full account the shaping that the existence of weld seam causesWhat the decline of performance and the movement of weld seam caused cannot, accurately by problems such as certain material location, have important reference value.And theoretical and experiment all empirical tests inverse analog method calculate weld movement measurer and have satisfied Engineering Reliability.

By with experiment contrast, although adopt the result of method inverse of the present invention and the value of actual measurement to have 36% when maximumDifference, but the trend of its prediction and actual conditions fit like a glove; Can reflected well than flange, squareShape part bottom section has larger weld movement amount. The present invention can be at the tailor welded blank forming Element Design initial stage, and fast prediction shouldThe situation of movement of part weld seam in actual drawing process, position and other technological parameters of convenient design weld seam, to fall as far as possibleThe decline of the performance that the movement of low weld seam causes, provides a kind of new method for solving accurately orientation problem.

Brief description of the drawings

Fig. 1 is Method And Principle figure of the present invention;

Fig. 2 is the location drawing of the embodiment of the present invention 1 desirable weld seam;

Fig. 3 is technical solution of the present invention step 3) calculate obtain initial displacement field u₀；

Fig. 4 is blank and the bonding wire figure that utilizes the present invention to obtain in embodiment 1;

Fig. 5 is laser assembly solder plate schematic diagram in embodiment 2;

Fig. 6 is that in embodiment 2, thin side plate applies bead schematic diagram;

Fig. 7 is without bead effect schematic diagram in embodiment 2;

Fig. 8 is without bead effect (pressure-pad-force reduces) schematic diagram in embodiment 2;

Fig. 9 is that in embodiment 2, surrounding all applies bead schematic diagram.

Detailed description of the invention

Below in conjunction with drawings and Examples, the present invention is further described.

Embodiment 1: quick obtaining blank position of bonding wire

What Fig. 2 showed is the part drawing after being shaped, and transversal AB is the position (not skew) of the desirable weld seam of setting, its end pointsA is also the reference point of measuring each point situation of movement on weld seam under each operating mode. Transversal CD is parallel with the length direction of part, withSetting bead direction is vertical, and is positioned at the center of part, and this cross section is respectively across the weldering of flange, sidewall and the bottom surface of thickness plate sideSeam region, can reflect variation tendency and the affect situation of different schemes on it of thickness and strain on this cross section.

Start with from drawing and forming part, carry out inverse analog calculating according to 4 kinds of schemes shown in table 1, scheme one, two, fourThe pressure-pad-force that adopts 70KN, scheme three adopts the pressure-pad-force of 40KN, and scheme one, four adopts the equivalence of 0.14KN/mm to drawProlong muscle model, obtain blank shape and the position while welding under different operating modes by calculating. Concrete steps are as follows:

According to technical solution of the present invention step 1) by discrete workpiece be triangular element, obtain formation of parts grid, to workpieceThe final configuration of plate is set up following virtual work equation

$W=\mathrm{\Σ}{\∫}_{V_e}{{\mathrm{\δ}}_{\mathrm{\ϵ}}}^T\mathrm{\σ}dV-{\∫}_{A_e}{{\mathrm{\δ}}_u}^{T}FdA=0---\left(1\right)$

δ ε in formula---in unit, the sham of arbitrfary point is moved; δ u---the virtual strain of arbitrfary point in unit; σ---Cauchy shouldPower; F---outer force vector; V_e---volumetric spaces; A_e---surf zone; T---represent transposed matrix;

Obtain invention technical scheme steps 2 according to formula (1)) in the finite element equation of a step simulation.

k(u)u＝p(u)(2)

K in formula (u)---stiffness matrix; P (u)---external force load vector; U---displacement;

Because formula (1) and formula (2) are all the functions of displacement components u, therefore formula (2) is a Nonlinear System of Equations, adopts bandNewton-Laplce method of convergence factor, the difference of supposing external force and internal force is R (u), its iterative equation is

$\left\{\begin{array}{c}{k}_T\left(u^i\right){\mathrm{\Δu}}^i=R\left(u^i\right)\\ u^{i+1}=u^i+{\mathrm{\ω\Δu}}^i\end{array}\right.---\left(3\right)$

ω in formula---iteration relaxation factor, Δ uⁱ---the displacement increment of i step, R (uⁱ)---the external force internal force of i stepPoor, uⁱ⁺¹---the displacement increment of i+1 step, uⁱ---the displacement increment of i step, k_T---tangent stiffness matrix;

In order to solve invention technical scheme steps 3) equation group, need to first calculate invention technical scheme steps 4) non-lineProperty equation group, in order to solve formula (3), need to provide an initial displacement field, i.e. the initial value of displacement components u, initial valueQuality has determined the efficiency that formula (3) solves; Suppose that external force load is zero,

k(u)u＝0(4)

K in formula (u)---stiffness matrix; U---displacement;

Similarly, obtain a Nonlinear System of Equations, adopt the newton-Laplce method with convergence factor, suppose that internal force value isF_in(uⁱ), its iterative equation is

$\left\{\begin{array}{c}{k}_T\left(u^i\right){\mathrm{\Δu}}^i=F_{in}\left(u^i\right)\\ u^{i+1}=u^i+{\mathrm{\ω\Δu}}^i\end{array}\right.---\left(5\right)$

ω in formula---iteration relaxation factor, Δ uⁱ---the displacement increment of i step, F_in(uⁱ)---the internal force of i step,uⁱ⁺¹---the displacement increment of i+1 step, uⁱ---the displacement increment of i step, k_T---tangent stiffness matrix;

Solve this equation group (5), obtain initial displacement field u₀, result of calculation as shown in Figure 3.

The grid of Fig. 3 is submitted to invention technical scheme steps 3 as initial solution) solve Nonlinear System of Equations, see formula (3).After newton-Laplce iteration convergence, be the tailor welded grid of exportable inverse, final solving result as shown in Figure 4.

Suppose to thin side direction and move as just, obtain on weld seam each point with respect to the displacement of terminal A.

At the tailor welded grid of formation of parts grid and inverse acquisition, the node of each unit, attachment weld place obtains two space songsLine l₁And l₂；

By two space curve l₁And l₂To X-Y plane projection, obtain two plane curve l ' respectively₁And l '₂; According to formula $\mathrm{\Δ}l=\underset{i=1}{\overset{N-1}{\Σ}}\sqrt{{\left(x_1^i-x_2^i\right)}^2+{\left(y_1^i-y_2^i\right)}^2}$ Calculate the side-play amount of weld seam;

Δ l in formula---weld excursion amount; N---curve l '₁And l '₂The hop count of on average being divided;---curve l '₁I pointAbscissa;---curve l '₁The ordinate of i point;---curve l '₂The abscissa of i point;---curve l '₂The ordinate of i point.

Table 1 experimental program

Scheme one	Thin plate side applies bead (cylinder pressure 0.35MPa)
		Scheme two	Without bead (cylinder pressure 0.35MPa)
Scheme three	Adopt less pressure-pad-force (cylinder pressure 0.20MPa)
		Scheme four	Surrounding applies bead (cylinder pressure 0.35MPa)

For the simple part of some shape matching, such as non-straight wall class part, can be by three-dimensional grid directly to X-Y planeProjection, thus required initial displacement field u obtained₀, this type of part requires not overlap to the grid after X-Y plane projection.

Verify the reliability of embodiment 1 result of calculation below.

The tailor welded that experimental section adopts is respectively 0.8mm and 1.2mm by two block sizes identical (240 × 160mm), thicknessRectangle plate (Fig. 5), adopt CO2 laser weld to form, bonding power is 4KW, speed of welding 3m/min. UsedExperiment material is Baosteel GM6409M cold-rolled steel sheet. The material property parameter of cold-rolled steel is as shown in table 2. Due to drawing of tailor weldedDark different from the drawing of whole plate, the design of mould also needs to consider the particularity of this respect. This experiment adopt tailor welded be byThe welding of two blocks of different-thickness plates forms, if punch, blank holder and die are all flat, thin plate side because of insufficient pressure wrinkling.What this testing program was taked is, on punch and blank holder, step is set, and die is constant, to ensure the requirement of part outer surface quality.In order to obtain the amount of movement of weld seam, adopt three-coordinates measuring machine to measure. The present invention is not limited to the data that experiment adopts,This experimental data is only as illustration.

Table 2 Baosteel GM6409M cold-rolled steel sheet performance parameter

The laser assembly solder plate part that the drawing experiment mould of comparative analysis reality and drawing are complete. After drawing parts is fixing, chooseMeasurement point adopts three-coordinates measuring machine to measure the movement of weld seam. Respectively each scheme drawing experimental data and numerical simulation result are enteredRow contrast, obtains the correlation curve figure shown in Fig. 6～9. Due to the simplification of inverse analog method boundary condition, do not consider to be out of shape and go throughThe impact of history on forming process, and ignored the weld seam effect of heat affected area around, add the error producing while measurement,The maximum deviation that two kinds of curves are produced in each scheme is respectively 36%, 24.8%, 24.2%, 30.3%. Find in addition,The result of numerical simulation is generally all less than the result of actual measurement. But the trend of numerical simulation result is consistent with experimental data: flange weld seam is significantly less than the amount of movement of rectangular-shaped piece bottom section weld seam to rear side to the amount of movement of thin side, illustrate forObtaining rational Strain Distribution needs mainly the weld movement of box part bottom section to be controlled.

Claims (2)

1. a laser assembly solder plate drawing process weld movement method for quick predicting, it is characterized in that, described Forecasting Methodology is only considered the shape of final workpiece, known parameters is the profile of workpiece, the thickness of original blank, unknown parameter has the shape of blank and the thickness of workpiece, these parameters are tried to achieve by minimizing plastic deformation merit, in order to ignore the impact in different distortion path, have made a series of hypothesis:

1. Large Elastic-Plastic Deformation, material is completely incompressible;

2. deformation process is that ratio loads, based on plastic deformation theory;

3. material etc. is to strengthening or anisotropic strengthening;

4. the effect of mould shows as drift normal pressure heterogeneous, the frictional force under drift and blank holder;

Described Forecasting Methodology specifically comprises the following steps:

1). by discrete workpiece be triangular element, formation of parts grid, sets up following virtual work equation to the final configuration of the plate of workpiece

δ ε in formula---the virtual displacement of arbitrfary point in unit; δ u---the virtual strain of arbitrfary point in unit; σ---cauchy stress; F---outer force vector; V_e---volumetric spaces; A_e---surf zone; T---represent transposed matrix;

2). set up the finite element equation of a step simulation

K in formula (u)---stiffness matrix; P (u)---external force load vector; U---displacement;

3). because formula (1) and formula (2) they are all the functions of displacement components u, therefore formula (2) is a Nonlinear System of Equations, newton-Laplce the method for employing with convergence factor, the difference of supposing external force and internal force is R (u), its iterative equation is

ω in formula---iteration relaxation factor, Δ uⁱ---the displacement increment of i step, R (uⁱ)---the external force internal force of i step is poor, uⁱ⁺¹---the displacement increment of i+1 step, uⁱ---the displacement increment of i step, k_T---tangent stiffness matrix;

4). in order to solve formula (3), need to provide an initial displacement field, i.e. the initial value of displacement components u, the quality of initial value has determined the efficiency that formula (3) solves; Suppose that external force load is zero,

k(u)u＝0(4)

K in formula (u)---stiffness matrix; U---displacement;

Similarly, obtain a Nonlinear System of Equations, adopt the newton-Laplce method with convergence factor, suppose that internal force value is F_in(uⁱ), its iterative equation is

ω in formula---iteration relaxation factor, Δ uⁱ---the displacement increment of i step, F_in(_u ⁱ)---the internal force of i step, uⁱ⁺¹---the displacement increment of i+1 step, uⁱ---the displacement increment of i step, k_T---tangent stiffness matrix;

Solve this equation group (5), obtain initial displacement field u₀; Then forward the 3rd to) step is the tailor welded grid of exportable inverse after newton-Laplce iteration convergence;

5). at the tailor welded grid of formation of parts grid and inverse acquisition, the node of each unit, attachment weld place obtains two space curve l₁And l₂；

6). by two space curve l₁And l₂To X-Y plane projection, obtain two plane curve l ' respectively₁And l '₂; According to formulaCalculate the side-play amount of weld seam;

Δ l in formula---weld excursion amount; N---curve l '₁And l '₂The hop count of on average being divided;---curve l '₁The abscissa of i point;---curve l '₁The ordinate of i point;---curve l '₂The abscissa of i point;---curve l '₂The ordinate of i point.

2. laser assembly solder plate drawing process weld movement method for quick predicting as claimed in claim 1, it is characterized in that, described step 4) in for non-straight wall class part, by formation of parts grid directly to X-Y plane projection, thereby obtain the 3rd) the required initial displacement field u of step₀, this type of part requires not overlap to the grid after X-Y plane projection.