Method for calculating welding effective heat input in welding simulation

Abstract

The invention discloses a method for calculating welding effective heat input in welding simulation, which comprises the following steps of: establishing a welding simulation model according to an actual size in a simulation system, defining material attributes and boundary conditions, and establishing a welding simulation heat source model; the welding simulation model comprises a first base metal, a second base metal and a molten pool; the molten pool is located at the joint of the first base metal and the second base metal, and a closed solid geometry is defined at the joint, so that the molten pool and a welding wire for welding are contained in the closed solid geometry; the closed solid geometry moves along with the welding wire along the welding track; heat input in the unit time of the internal area of the closed solid geometry is defined as total input power, and heat transferred from the internal area to the external area in the unit time of the closed solid geometry is defined as heat loss power; the heat loss power is calculated based on the change of the temperature in transfer, the effective heat input power is calculated according to the heat loss power, the calculated effective heat input is more accurate and convenient, and optimization of a simulation heat source model is facilitated.

Description

Technical Field

[0001] The invention relates to the field of welding, and in particular to a method for calculating effective welding heat input in welding simulation. Background Art

[0002] Welding simulation is a complex process involving the interaction of multiple physical fields, such as heat conduction, mechanical behavior, and material deformation. As an important part of welding simulation, the heat source model is used to describe the heat conduction and heat source distribution during welding. When the heat input is too large, it will increase unnecessary power consumption and may cause overheating of the weld, coarse grain size, reduced toughness, and welding defects such as "bite edge". On the contrary, when the heat input is too small, the weld may not reach a sufficient penetration depth, resulting in welding defects such as "incomplete penetration", thereby affecting the strength of the weld; therefore, it is necessary to optimize the welding parameters in the welding simulation heat source model through the obtained welding heat input; in the traditional calculation of welding heat input, the thermal efficiency factor needs to be calculated, but the calibration and detection of the thermal efficiency factor are difficult. Summary of the invention

[0003] Purpose of the invention: In order to overcome the deficiencies in the prior art, the present invention provides a method for calculating the effective heat input of welding in welding simulation, by setting a virtual closed three-dimensional geometric body at the welding position, and calculating the welding heat input based on the heat loss dissipated from the inside to the outside of the closed three-dimensional geometric body, and adjusting the welding parameters according to the welding heat input to optimize the welding simulation heat source model.

[0004] Technical solution: To achieve the above-mentioned purpose, a method for calculating effective heat input of welding in a welding simulation of the present invention comprises establishing a welding simulation model according to actual size in a simulation system, defining material properties and boundary conditions, and establishing a welding simulation heat source model; the welding simulation model comprises a first parent material, a second parent material and a molten pool; the molten pool is located at the connection between the first parent material and the second parent material, and the position of the contact point between the molten pool and the welding wire defines a closed three-dimensional geometric body, and the closed three-dimensional geometric body moves along the welding trajectory with the welding wire; the heat input per unit time in the internal area of ​​the closed three-dimensional geometric body is defined as the total input power, and the heat transferred from the internal to the external area of ​​the closed three-dimensional geometric body per unit time is defined as the heat loss power; the heat loss power is calculated based on the change of temperature during the transfer, and the effective heat input power is calculated based on the heat loss power.

[0005] Furthermore, when in the welding simulation, the first parent material and the second parent material are connected by the molten pool, and the bottom of the molten pool does not penetrate the first parent material and the second parent material; the closed three-dimensional geometric body wraps the welding wire to be melted, the molten pool, a part of the first parent material close to one side of the molten pool, a part of the second parent material close to one side of the molten pool, and the space above the molten pool.

[0006] Furthermore, the cross section of the closed solid geometric body in contact with the air in the upper space is defined as an upper air surface, and the upper air surface is defined as an air contact surface.

[0007] Furthermore, when in welding simulation, the first parent material and the second parent material are connected through the molten pool, and the bottom of the molten pool penetrates the first parent material and the second parent material; the closed three-dimensional geometric body wraps the welding wire to be melted, the molten pool, a part of the first parent material close to one side of the molten pool, a part of the second parent material close to one side of the molten pool, the space above the molten pool and the space below the molten pool.

[0008] Furthermore, the cross section where the closed solid geometric body contacts the air in the upper space is defined as the upper air surface, the cross section where the closed solid geometric body contacts the air in the lower space is defined as the lower air surface, and both the upper air surface and the lower air surface are defined as air contact surfaces.

[0009] Furthermore, the power of the heat loss is calculated as follows:

[0010] dP 损失 =λdT / dl dA ε

[0011]

[0012] In the formula, dT / dl is the speed of temperature change in the direction, λ is the thermal conductivity of air, A ε is the area of ​​the upper air surface ε(63), and straight line l is the normal direction of ε.

[0013] Furthermore, the effective heat input φ of welding per unit time is calculated based on the final heat loss and the total welding heat input. The calculation process is as follows:

[0014] Q 有效 =W 总 -Q 损失 =UIt-Q 损失

[0015]

[0016]

[0017] Where U is the arc voltage of welding, I is the welding current, and t is the welding time.

[0018] Furthermore, when the closed solid geometric body is spherical, the intersection of the same horizontal plane where the upper surface of the first parent material and the upper surface of the second parent material are located and the extension line of one end of the welding wire toward the molten pool is defined as the center of the closed solid geometric body.

[0019] Beneficial effects: The method for calculating effective heat input of welding in a welding simulation of the present invention sets a virtual closed solid geometric body at the welding position, and calculates the welding heat input based on the heat loss dissipated from the inside to the outside of the closed solid geometric body, so that the calculation of welding heat input is simpler and more accurate; by adjusting the size of the solid geometric body, it can be more suitable for the heat input calculation of different welding methods, so that the calculation of welding heat input of different welding methods is more accurate; optimizing the welding simulation heat source model can more realistically reflect the temperature field and thermal stress distribution during the welding process, thereby improving the accuracy of welding simulation. By optimizing the heat source model, the temperature distribution, thermal stress, deformation and other information of the welding joint can be more accurately predicted, providing strong support for the optimization of the welding process. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is the welding simulation process flow chart;

[0021] Figure 2 It is a schematic diagram of the sliced ​​surface of a closed solid geometric body in which the welding simulation molten pool does not penetrate the parent material;

[0022] Figure 3 It is a schematic diagram of the cross-section of a closed solid geometric body in which the welding simulation molten pool penetrates the parent material;

[0023] Figure 4 The schematic diagram of the sliced ​​surface of a cube is a closed solid geometric body in which the welding simulation molten pool does not penetrate the parent material;

[0024] Figure 5 The closed solid geometric body of the welding simulation molten pool penetrating the parent material is a schematic diagram of the sliced ​​surface of a cube. DETAILED DESCRIPTION

[0025] The present invention will be further described below in conjunction with the accompanying drawings.

[0026] like Figure 1 As shown in the figure, under the production mode of the traditional battery tray welding process, it is impossible to form a feedback to the welding tooling design module, resulting in each tooling design being similar to the re-production of a new product. Based on this, a set of welding process flows was redesigned, such as Figure 1 As shown, the purpose is to be able to feed back the data from the production process to the design end and the production process under this process, so that the problems encountered in the production process before can be optimized or even solved in the early design process.

[0027] A new welding process flow includes the following steps: first, product input, then welding simulation; tooling design, which mainly includes simulation of welding trajectory and production of tooling, such as setting simulated base material, welding wire, welding voltage and current; judging whether the welding trajectory is suitable for the current welding simulation needs, otherwise optimizing the simulation trajectory, and setting CMT parameters and performing CMT welding; after the simulation welding is completed, judging whether the weld is qualified, if so, entering the welding database, optimizing the simulation heat source model module and outputting the simulation product, otherwise adjusting the CMT parameters; judging whether the welding size is qualified, if so, outputting the simulation product; otherwise adjusting the tooling, and optimizing the simulation model tooling load module.

[0028] According to the different materials of the first parent material and the second parent material, according to their physical properties and welding requirements, the effective heat input required for welding is different. In simulation welding, the input of total power is only to output a certain current and voltage to the welding wire through the welding gun for welding; however, the input current and voltage are not the most accurate, and the welding current and welding voltage can only be temporarily set at the power closest to the welding power. In simulation welding, it is necessary to judge whether the effective heat input of welding meets the current effective heat input according to the calculated or detected effective heat input. If it is too large or too small, adjust the welding parameters such as welding voltage and welding current. Even if the material of the parent material is the same, due to different welding methods and different boundary conditions of the welding parent material, if the welding parent material becomes thinner, the simulation heat source model with the previously set welding parameters will cause the effective heat input to increase, increase unnecessary power consumption, and may cause the weld to overheat, coarse grain size, and reduce toughness; therefore, it is necessary to adjust the welding parameters to optimize the simulation heat source model so that the optimized simulation heat source model can reach the most suitable value for the effective heat input of welding, so that the weld is better quality.

[0029] A method for calculating effective heat input of welding in welding simulation includes establishing a welding simulation model according to actual size in a simulation system, defining material properties and boundary conditions, and establishing a welding simulation heat source model; the welding simulation model includes a first base material 1, a second base material 2 and a molten pool 3; the molten pool 3 is located at the connection between the first base material 1 and the second base material 2, and the position of the contact point between the molten pool 3 and the welding wire 4 defines a closed solid geometric body 6, and the closed solid geometric body 6 moves along the welding track with the welding wire 4; the heat input per unit time in the internal area of ​​the closed solid geometric body 6 is defined as the total input power, and the heat transferred from the inside to the outside area of ​​the closed solid geometric body 6 per unit time is defined as the heat loss power; the heat loss power is calculated based on the change of temperature during the transfer, and the effective heat input power is calculated based on the heat loss power. From another perspective, when welding, part of the energy is converted into heat energy, and the energy of using this heat energy to heat and melt the welding rod and the workpiece is effective, and the rest of the energy will be lost; the total input power of welding is subtracted from the heat loss power, that is, the effective heat input power is obtained. According to the effective heat input of welding, the welding parameters are adjusted to optimize the welding simulation heat source model.

[0030] like Figure 2 As shown, in the welding simulation, the first parent material 1 and the second parent material 2 are connected through the molten pool 3, and the bottom of the molten pool 3 does not penetrate the first parent material 1 and the second parent material 2; that is, the side of the first parent material 1 close to the molten pool 3 and a part of the side of the second parent material 2 close to the molten pool 3 are connected through the molten pool 3, and the side of the first parent material 1 close to the molten pool 3 and the other part of the side of the second parent material 2 close to the molten pool 3 are in direct contact with the first parent material 1 and the second parent material 2; define the contact type between the first parent material 1 and the second parent material 2 and the molten pool 3, the closed three-dimensional geometric body 6 encloses the welding wire 4 to be melted, the molten pool 3, a part of the first parent material 1 close to the side of the molten pool 3, a part of the second parent material 2 close to the side of the molten pool 3 and the space above the molten pool 3. The closed three-dimensional geometric body 6 does not hinder the transfer of heat, and heat can be transferred through the closed three-dimensional geometric body without hindrance.

[0031] The closed solid geometric body 6 wraps the molten pool at the welding position as much as possible, but for the convenience of calculation, it will inevitably wrap a part of the first parent material and the second parent material, and also wrap a part of the space on the molten pool. The collection body can be a sphere, which conforms to the shape of the simulation heat source model; the molten pool, arc, molten welding wire and molten parent material are regarded as a system, then part of the internal energy of the system is used for welding, and the other part flows out of the system, becoming Q loss.

[0032] Under ideal conditions, during the welding process, when the welding parameters are constant and the arc starting and arc ending positions and the melting behavior of the welding wire are not considered, the sliced ​​surface is in a state of thermal equilibrium, that is, the shape and temperature of each position do not change with time. The center of the heat source is defined as the center of the geometric body, and a closed three-dimensional geometric body such as a sphere is taken so that the geometric body can just contain the welding arc, the molten pool, the welding wire to be melted, and the parent material to be melted. Then the energy transferred from the system inside the geometric body to the outside of the geometric body is approximately equal to the Q loss; the smaller the geometric body, the more accurate the effective heat input of the calculation result. When the closed three-dimensional geometric body 6 is spherical, the intersection of the same horizontal plane where the upper surface of the first parent material 1 and the upper surface of the second parent material 2 are located and the extension line of the welding wire 4 toward one end of the molten pool 3 is defined as the center of the sphere of the closed three-dimensional geometric body 6. At this time, the radius of the spherical three-dimensional geometric body is set according to the shape and size of the molten pool, and the molten pool is completely wrapped in the closed three-dimensional geometric body.

[0033] The set closed solid geometric body 6 moves along the welding simulation trajectory following the welding wire 4 at the head of the welding gun 5, because the base material to be welded may not always be flat during welding. When welding to the curved, weak or thickened part of the base material, the current effective heat input for the welding here will cause the heat loss to change due to the different thickness of the base material and the size of the contact surface, and the effective heat input of the welding will also change. The effective heat input in the welding simulation is detected in real time. If the effective heat input required for the welding of the base material is detected to be too large or too small, the welding parameters are adjusted in time to optimize the welding simulation heat source model. If the result of calculating the effective heat input of welding in the welding simulation is too different from the actual one, a series of heat source models such as the double ellipsoid heat source model can be selected for optimization by adjusting the thermal conductivity, thermal efficiency parameters, and the selection method of the heat source model, so as to achieve the result of calculating the effective heat input in the actual welding; therefore, the calculation of the effective heat input can also be the result that the effective heat input cannot be calculated in the actual welding, and the actual welding is simulated by the simulation welding, and then the effective heat input is calculated by the method or calculation formula to obtain the effective heat input closest to the actual welding.

[0034] At the same time, in the process of a certain simulated welding, for example, when the base material changes from thin to thick, the detected effective heat input will increase, because most of the heat will flow to the melted base material, but the simulated welding at this time will not be in a state of thermal equilibrium, breaking the thermal equilibrium of welding, and may not reach the effective heat input required for welding; therefore, it is necessary to adjust the welding parameters, increase the total input power of welding, and optimize the simulated heat source model of welding, so that the simulated welding can reach the thermal equilibrium of welding at one time. When the base material changes from thick to thin, the detected effective heat input will decrease, the heat input of the base material melting welding will decrease, and most of the heat will flow to the outside of the weld, causing the heat loss to increase; at this time, the simulated welding will not be in a state of thermal equilibrium, breaking the thermal equilibrium of welding, and a large amount of heat will dissipate from the original molten pool range, causing the molten pool to become larger, reducing the toughness of welding, so it is necessary to adjust the welding parameters, reduce the total input power of welding, and optimize the simulated heat source model of welding, so that the simulated welding can reach the thermal equilibrium of welding at one time.

[0035] The cross section of the closed solid geometric body 6 in contact with the air in the upper space is defined as the upper air surface 63. The heat inside the closed solid geometric body 6 is transferred to the air through the upper air surface 63, and the upper air surface 63 is defined as the air contact surface. The power of the heat loss is calculated as follows:

[0036] dP 损失 =λdT / dl dA ε

[0037]

[0038] Where dT / dl is the speed of temperature change in the direction, λ is the thermal conductivity of air, A ε is the area of ​​the upper air surface ε(63), and straight line l is the normal direction of ε.

[0039] Based on the final heat loss and the total welding heat input, the effective heat input φ of welding per unit time is calculated. The calculation process is as follows:

[0040] Q 有效 =W 总 -Q 损失 =UIt-Q 损失

[0041]

[0042]

[0043] Where U is the arc voltage of welding, I is the welding current, and t is the welding time.

[0044] When the closed solid geometric body 6 is a sphere, assuming that the closed solid geometric body 6 is a sphere with a radius of a, the center of the sphere is at the center of the molten pool, a spatial polar coordinate system is established at the center of the sphere, (θ, ρ, r) are polar coordinate parameters, then the polar coordinate equation of the upper sphere is:

[0045] r=a(0≤θ≤2π, 0≤ρ≤π / 2)

[0046] Substitute into the formula:

[0047]

[0048] get:

[0049]

[0050]

[0051] Thermal conductivity λ is a physical quantity related to temperature T. Assuming that temperature T (θ, p, r) is distributed in a spherical gradient, the center of the sphere is the origin of the coordinate system, that is, temperature T is only related to r, then on the upper spherical surface (that is, when r = a), temperature T is a constant, denoted as T0, and the thermal conductivity of air at T0 is denoted as λ0, then:

[0052]

[0053]

[0054] P 损失 =2πa 2 λ0T′ (a) =λ0T′ (a) A ε

[0055] The effective heat input φ is calculated as follows:

[0056] φ=UI-P 损失 =UI-2πa 2 λ0T′ (a) .

[0057] like Figure 3As shown, in the welding simulation, the first parent material 1 and the second parent material 2 are connected through the molten pool 3, and the bottom of the molten pool 3 penetrates the first parent material 1 and the second parent material 2; that is, the side of the first parent material 1 close to the molten pool 3 and the side of the second parent material 2 close to the molten pool 3 are all connected through the molten pool 3, and the first parent material 1 and the second parent material 2 are not in direct contact; define the contact type between the first parent material 1 and the second parent material 2 and the molten pool 3, and the defined contact type can be rigid contact. The closed solid geometric body 6 encloses the welding wire 4 to be melted, the molten pool 3, a part of the first parent material 1 close to the side of the molten pool 3, a part of the second parent material 2 close to the side of the molten pool 3, the space above the molten pool 3, and the space below the molten pool 3.

[0058] The cross-section where the closed three-dimensional geometric body 6 contacts the air in the upper space is defined as the upper air surface 63, and the cross-section where the closed three-dimensional geometric body 6 contacts the air in the lower space is defined as the lower air surface 64. The internal heat of the closed three-dimensional geometric body 6 is transferred to the air through the upper air surface 63 and the lower air surface 64, and the upper air surface 63 and the lower air surface 64 are both defined as air contact surfaces.

[0059] The power of heat loss on the air contact surface is calculated as follows:

[0060] dP 损失 =λdT / dl dA ε

[0061]

[0062] Where dT / dl is the temperature change per unit length, and the straight line l is the normal direction of ε, λλ is the thermal conductivity of air, and A ε is the total area of ​​the cross sections ε at the upper air surface 63 and the lower air surface 64; and the effective heat input is calculated based on the heat loss of the air surface.

[0063] like Figure 4 As shown, when the closed three-dimensional geometric body 6 is a cube, the first parent material 1 side and the second parent material 2 are connected through the molten pool 3, and the bottom of the molten pool 3 penetrates the first parent material 1 and the second parent material 2, the closed three-dimensional geometric body of the cube can include the welding wire, the molten pool 3, a part of the first parent material 1, a part of the second parent material 2 and a part of the space above the molten pool 3; at this time, due to the welding method and the change of the welding wire, the molten pool 3 will not protrude. At this time, the use of a cube or a cuboid can make the upper surface of the closed three-dimensional geometric body close to the upper surface of the first parent material, the upper surface of the molten pool and the upper surface of the second parent material, thereby reducing heat dissipation in the air and increasing the calculation accuracy of the effective heat input.

[0064] like Figure 5As shown, when the first parent material 1 and the second parent material 2 are connected by the molten pool 3, and the bottom of the molten pool 3 does not penetrate the first parent material 1 and the second parent material 2, the closed three-dimensional geometric body of the cube can still contain the welding wire, the molten pool 3, a part of the first parent material 1, a part of the second parent material 2 and a part of the space above the molten pool 3; when the spherical closed three-dimensional geometric body wraps the molten pool that penetrates the first parent material and the second parent material at the bottom, due to the spherical shape, when wrapping the molten pool, it will inevitably wrap a part of the space at the bottom of the molten pool; however, when the closed three-dimensional geometric body is a cube, when wrapping the molten pool, it can be close to the surface of the molten pool, because the lower part of the molten pool does not protrude, so the closed three-dimensional geometric body of the cube The lower surface of the solid geometric body can be in close contact with the lower surface of the first parent material, the lower surface of the molten pool and the lower surface of the second parent material at the same time; because of the different types of welding, the upper surface of the weld, i.e. the molten pool, will not protrude due to different welding methods. At this time, the upper surface of the cubic closed solid geometric body can also be in close contact with the upper surface of the first parent material, the upper surface of the molten pool and the upper surface of the second parent material. At this time, heat loss will not be directly lost in the air, but heat will be dissipated outwards through the upper and lower surfaces of the molten pool, the first parent material, the second parent material and the contact surface of the closed solid geometric body. Therefore, the heat loss dissipated outwards by the air surface can be removed in the calculation, thereby making the calculation of effective heat input more accurate.

[0065] When the closed solid geometric body 6 is a cube, and the upper and lower surfaces of the cube can be close to the upper and lower surfaces of the molten pool, it is assumed that the closed solid geometric body 6 is a cube with a side length of a, λ does not change with the change of temperature, y=dT / dl, and the temperature gradient y does not change with the change of position. The process of calculating the effective heat input φ is as follows:

[0066]

[0067]

[0068] Where λ is the thermal conductivity, yleft, yright, yfront, yback and ytop are the temperature gradients on the left, right, front, back and top of the cube respectively, and A ε is the total area of ​​the closed solid geometric body in contact with the air cross section ε. This is an ideal state. In the actual welding process, λ and y will change, but the simulation software can detect the temperature of each position in real time and select the appropriate λ and y values ​​according to the temperature value of the position.

[0069] Example

[0070] In the simulation welding process, most of the heat is the heat dissipated from the welding molten pool, or the heat loss caused by welding spatter; however, in the actual welding process, when the welding wire is heated by a welding gun and placed at the connection between the two base materials, the part of the two base materials close to the welding wire begins to melt under the action of the welding wire and high temperature, and finally forms a molten pool, and then solidifies into a weld; in this process, the heat of melting the two base materials, during the melting process, due to the thermal conductivity of the base material itself, a part of the heat will still be transferred from the molten pool to the position of the base material without welding, and finally dissipated into the air, and will not be used to form heat loss in actual welding. Therefore, considering that part of the heat is transferred to other non-welded parts of the base material by the thermal conductivity of the base material, the heat loss of this part is also recorded as heat loss; in the welding simulation, the heat loss of heat transferred to other non-welded positions of the base material through closed solid geometry 6 is added.

[0071] Based on the above analysis, if Figure 2 As shown, in the welding simulation, the first parent material 1 side and the second parent material 2 are connected through the molten pool 3, and the bottom of the molten pool 3 penetrates the first parent material 1 and the second parent material 2; that is, the side of the first parent material 1 close to the molten pool 3 and the side of the second parent material 2 close to the molten pool 3 are all connected through the molten pool 3, and the first parent material 1 and the second parent material 2 are not in direct contact; define the contact type between the first parent material 1 and the second parent material 2 and the molten pool 3, and the defined contact type can be rigid contact. The closed solid geometric body 6 encloses the welding wire 4 to be melted, the molten pool 3, a part of the first parent material 1 close to the side of the molten pool 3, a part of the second parent material 2 close to the side of the molten pool 3, and the space above the molten pool 3.

[0072] The cross section of the closed three-dimensional geometric body 6 in contact with the air in the upper space is defined as the upper air surface 63, the cross section of the closed three-dimensional geometric body 6 in contact with the first parent material 1 is defined as the first parent material contact surface 61, the cross section of the closed three-dimensional geometric body 6 in contact with the second parent material 2 is defined as the second parent material contact surface 62, and the cross section of the closed three-dimensional geometric body 6 in contact with the weld after the molten pool solidifies is defined as the weld contact surface; the heat inside the closed three-dimensional geometric body 6 is transferred to the air through the upper air surface 63, and the heat inside the closed three-dimensional geometric body 6 is transferred to the parts of the first parent material 1 and the second parent material 2 that are not being welded through the first parent material contact surface 61, the second parent material contact surface 62 and the weld contact surface; the upper air surface 63 is defined as the air contact surface, and the first parent material contact surface 61, the second parent material contact surface 62 and the weld contact surface are all defined as parent material contact surfaces.

[0073] The power of the heat loss of the air contact surface and the power of the heat loss of the base material contact are combined to obtain the final heat loss. The calculation process is as follows:

[0074]

[0075]

[0076] Wherein, ε represents the upper air surface 63; represents the sum of the first parent metal contact surface 61, the second parent metal contact surface 62 and the weld contact surface after the molten pool solidifies; dT / dl is the temperature change per unit length, is the thermal conductivity of the base material, The first base metal contact surface 61, the second base metal contact surface 62 and the weld contact surface after the molten pool solidifies The sum of the areas of for The normal direction of ε is the thermal conductivity of air, A ε is the area of ​​the upper air surface 63ε, l ε is the normal direction of ε.

[0077] Based on the final heat loss and the total welding heat input, the effective heat input φ of welding per unit time is calculated. The calculation process is as follows:

[0078]

[0079]

[0080] In the formula, for The normal direction, l ε is the normal direction of ε, U is the welding arc voltage, I is the welding current, and t is the welding time.

[0081] like Figure 3 As shown, in the welding simulation, the first parent material 1 side and the second parent material 2 are connected through the molten pool 3, and the bottom of the molten pool 3 penetrates the first parent material 1 and the second parent material 2; that is, the side of the first parent material 1 close to the molten pool 3 and the side of the second parent material 2 close to the molten pool 3 are all connected through the molten pool 3, and the first parent material 1 and the second parent material 2 are not in direct contact; define the contact type between the first parent material 1 and the second parent material 2 and the molten pool 3, and the defined contact type can be rigid contact. The closed solid geometric body 6 encloses the welding wire 4 to be melted, the molten pool 3, a part of the first parent material 1 close to the side of the molten pool 3, a part of the second parent material 2 close to the side of the molten pool 3, the space above the molten pool 3, and the space below the molten pool 3.

[0082] The cross section of the closed three-dimensional geometric body 6 in contact with the air in the upper space is defined as the upper air surface 63, the cross section of the closed three-dimensional geometric body 6 in contact with the air in the lower space is defined as the lower air surface 64, the cross section of the closed three-dimensional geometric body 6 in contact with the first parent material 1 is defined as the first parent material contact surface 61, the cross section of the closed three-dimensional geometric body 6 in contact with the second parent material 2 is defined as the second parent material contact surface 62, and the cross section of the closed three-dimensional geometric body 6 in contact with the weld after the molten pool solidifies is defined as the weld contact surface; the internal heat of the closed three-dimensional geometric body 6 is transferred to the air through the upper air surface 63 and the lower air surface 64, and the internal heat of the closed three-dimensional geometric body 6 is transferred to the parts of the first parent material 1 and the second parent material 2 that are not being welded through the first parent material contact surface 61, the second parent material contact surface 62 and the weld contact surface; the upper air surface 63 and the lower air surface 64 are defined as air contact surfaces, and the first parent material contact surface 61, the second parent material contact surface 62 and the weld contact surface are all defined as parent material contact surfaces.

[0083] The power of the heat loss of the air contact surface and the power of the heat loss of the base metal contact are combined to obtain the final heat loss. Based on the final heat loss and the total welding heat input, the effective heat input φ of welding per unit time is calculated. The calculation process is as follows:

[0084]

[0085]

[0086] Wherein, U is the arc voltage of welding, I is the welding current, t is the welding time; ε is the sum of the upper air surface 63 and the lower air surface 64, represents the sum of the first parent metal contact surface 61, the second parent metal contact surface 62 and the weld contact surface after the molten pool solidifies, dT / d1 is the temperature change per unit length, for The normal direction of is the thermal conductivity of the base material, for The sum of the areas of ε is the normal direction of ε, λ ε is the thermal conductivity of air, A ε is the sum of the areas of ε, that is, A ε It is the total area of ​​the cross sections ε at the upper air surface 63 and the lower air surface 64.

[0087] The above is only a description of the preferred embodiments of the present invention. Ordinary technicians in this technical field can make several modifications and optimizations based on the above disclosure without departing from the above basic principles. These improvements and optimizations should be regarded as the understood protection scope of the present invention.

Claims

1. A method for calculating effective heat input of welding in welding simulation, characterized in that: The invention comprises establishing a welding simulation model according to the actual size in a simulation system, defining material properties and boundary conditions, and establishing a welding simulation heat source model; the welding simulation model comprises a first base material (1), a second base material (2) and a molten pool (3); the molten pool (3) is located at the connection between the first base material (1) and the second base material (2); the contact point between the molten pool (3) and the welding wire (4) defines a closed solid geometric body (6); the closed solid geometric body (6) moves along the welding track following the movement of the welding wire (4); the heat input per unit time into the internal area of ​​the closed solid geometric body (6) is defined as the total input power; the heat transferred from the internal area to the external area of ​​the closed solid geometric body (6) per unit time is defined as the heat loss power; the heat loss power is calculated based on the change of temperature during the transfer, and the effective heat input power is calculated based on the heat loss power.

2. The method for calculating effective heat input of welding in welding simulation according to claim 1, characterized in that: When, in a welding simulation, the first parent material (1) and the second parent material (2) are connected via a molten pool (3), and the bottom of the molten pool (3) does not penetrate the first parent material (1) and the second parent material (2); the closed three-dimensional geometric body (6) encloses a welding wire (4) to be melted, the molten pool (3), a portion of the first parent material (1) close to one side of the molten pool (3), a portion of the second parent material (2) close to one side of the molten pool (3), and a space above the molten pool (3).

3. The method for calculating effective heat input of welding in welding simulation according to claim 2, characterized in that: The cross section of the closed solid geometric body (6) in contact with the air in the upper space is defined as an upper air surface (63), and the upper air surface (63) is defined as an air contact surface.

4. The method for calculating effective heat input of welding in welding simulation according to claim 1, characterized in that: When, in a welding simulation, the first parent material (1) and the second parent material (2) are connected via the molten pool (3), and the bottom of the molten pool (3) penetrates the first parent material (1) and the second parent material (2); the closed three-dimensional geometric body (6) encloses the welding wire (4) to be melted, the molten pool (3), a portion of the first parent material (1) close to one side of the molten pool (3), a portion of the second parent material (2) close to one side of the molten pool (3), a space above the molten pool (3), and a space below the molten pool (3).

5. The method for calculating effective heat input of welding in welding simulation according to claim 4, characterized in that: The cross section of the closed three-dimensional geometric body (6) in contact with the air in the upper space is defined as the upper air surface (63), the cross section of the closed three-dimensional geometric body (6) in contact with the air in the lower space is defined as the lower air surface (64), and both the upper air surface (63) and the lower air surface (64) are defined as air contact surfaces.

6. The method for calculating effective heat input of welding in welding simulation according to claim 3, characterized in that: The power of the heat loss is calculated as follows: dP 损失 =λdT / dl dA ε Where dT / dl is the rate of change of temperature in the direction, λ is the thermal conductivity of air, Aε is the area of ​​the upper air surface ε(63), and straight line l is the normal direction of ε.

7. The method for calculating effective heat input of welding in welding simulation according to claim 6, characterized in that: Based on the final heat loss and the total welding heat input, the effective heat input φ of welding per unit time is calculated. The calculation process is as follows: Q 有效 =W 总 -Q 损失 =UIt-Q 损失 Where U is the arc voltage of welding, I is the welding current, and t is the welding time.

8. The method for calculating effective heat input of welding in welding simulation according to claim 3, characterized in that: When the closed solid geometric body (6) is spherical, the intersection of the same horizontal plane where the upper surface of the first parent material (1) and the upper surface of the second parent material (2) are located and the extension line of one end of the welding wire (4) toward the molten pool (3) is defined as the center of the closed solid geometric body (6).

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