A non-indentation spot welding production process for automobile parts

Abstract

The invention relates to a non-indentation spot welding production process for automobile parts, belonging to the technical field of automobile parts welding. The invention firstly uses the principles of mechanics and thermodynamics to calculate the heat input, heat conduction, thermal expansion, contraction and residual stress generated in the welding process, and then estimates the welding deformation between different parts, increases the overall rigidity of the weld in the welding area with small deformation and the welding area with large deformation, and sets an anti-deformation device on one side of the part in the welding area with medium deformation. The welding area with small deformation is welded first, then the welding area with medium deformation is welded, and finally the welding area with large deformation is welded, so that the overall welding deformation is reduced. After the welding sequence between the parts is changed as mentioned above, the overall rigidity of the weld is used to resist the generation of welding deformation as much as possible, thereby effectively reducing the welding deformation.

Description

Technical Field

[0001] The invention belongs to the technical field of automobile parts welding, and in particular relates to a non-indentation spot welding production process for automobile parts. Background Art

[0002] The indentation-free spot welding production process is a high-quality welding technology used for welding automotive parts. Its purpose is to reduce or avoid indentations in the welding area during the welding process, thereby maintaining the appearance and performance of the parts. In the indentation-free spot welding production process for automotive parts, the indentations generated during the welding process are usually reduced or eliminated by precisely controlling the welding parameters and the mechanical behavior during the welding process.

[0003] However, there are some problems with the current production process of indentation-free spot welding of automotive parts: when performing indentation-free spot welding on large assembly parts that are the main components of the body-in-white, since the large assembly parts are composed of many parts and the parts are overlapped with the rest of the body-in-white on all sides, the accuracy of the control surface is required to be high. In the face of so many parts, in order to ensure the accuracy of indentation-free spot welding, it is necessary to adjust the welding parameters according to different parts, which requires the equipment to be able to adapt to many materials. Each adjustment of welding parameters will inevitably be affected by environmental factors. Multiple adjustments to many materials may reduce the accuracy of welding parameters, and ultimately lead to an increase in the welding deformation of large assembly parts. In this regard, a production process for indentation-free spot welding of automotive parts is proposed, which reduces the welding deformation by correcting all parts in large assembly parts. Summary of the invention

[0004] In order to solve the above-mentioned problems existing in the prior art, the present invention provides a non-indentation spot welding production process for automobile parts, which solves the problem that each adjustment of welding parameters in the prior art is inevitably affected by environmental factors, and multiple adjustments for many materials may reduce the accuracy of welding parameters, ultimately leading to an increase in the welding deformation of large assembly parts.

[0005] The purpose of the present invention can be achieved by the following technical solution: A production process for spot welding of automobile parts without indentation, comprising the following steps:

[0006] S1: Using the principles of mechanics and thermodynamics, calculate the heat input, heat conduction, thermal expansion, contraction and residual stress generated during welding, and then estimate the welding deformation between different parts;

[0007] S2: The deformation between 0.1mm and 1mm, the deformation between 1mm and 5mm, and the deformation greater than 5mm are defined as the small deformation welding area, the medium deformation welding area, and the large deformation welding area respectively;

[0008] S3: Compare the estimated welding deformation with the small deformation welding area, the medium deformation welding area and the large deformation welding area, and divide the welding deformation generated by welding between different parts into the small deformation welding area, the medium deformation welding area and the large deformation welding area;

[0009] S4: Correct the welding deformation of the small deformation welding area, medium deformation welding area and large deformation welding area, increase the overall rigidity of the welding in the small deformation welding area and the large deformation welding area, set an anti-deformation device on one side of the part in the medium deformation welding area, weld the small deformation welding area first, then weld the medium deformation welding area, and finally weld the large deformation welding area to reduce the overall welding deformation.

[0010] As a further solution of the present invention, before welding the small deformation welding area in S4, the parts to be welded are fixed on the welding platform by a plurality of clamps, and there are multiple anti-deformation devices, and each anti-deformation device is arranged on the flip arm of the corresponding clamp.

[0011] As a further solution of the present invention, the anti-deformation device includes a clamping block, which is arranged on the flip arm of the clamp. The clamping block is arranged on one side of the part in the medium deformation welding area, and the clamping block is made of strong clamping steel. The clamping block cooperates with the clamp to limit the movement of the part control surface and thus reduce the welding deformation.

[0012] As a further solution of the present invention, the clamping block is provided with a gasket for absorbing its own tolerance, and the position of the clamping block with respect to the component is adjusted by the gasket.

[0013] As a further solution of the present invention, in S4, the number of welding spots is increased in the small deformation welding area and the large deformation welding area to increase the overall rigidity of the welding in the small deformation welding area and the large deformation welding area.

[0014] As a further solution of the present invention, the number of welds in the welding area with small deformation in S4 is greater than the number of welds in the welding area with large deformation.

[0015] As a further solution of the present invention, when welding the medium deformation welding area in S4, the following steps are included:

[0016] S41: Clean the medium deformation welding area to ensure that there is no oil, rust or other impurities;

[0017] S42: Perform preliminary welding first, starting from the area with less welding difficulty and less stress, starting from the middle and gradually expanding to both sides;

[0018] S43: Weld the main structure and main frame to ensure the stability and strength of the main structure;

[0019] S44: welding of secondary structures;

[0020] S45: Welded connections:

[0021] S46: Perform proper trimming and repair welding on the weld to ensure the weld quality;

[0022] S47: Carry out necessary cooling, heat treatment, grinding and testing to ensure that the welding quality meets the requirements.

[0023] As a further solution of the present invention, the adjustment method of the anti-deformation device is the same as the adjustment method of the clamp.

[0024] As a further solution of the present invention, the anti-deformation device in S4 is designed separately, and the device is designed with an adjustable part, which has a lower requirement on the installation accuracy.

[0025] The beneficial effects of the present invention are:

[0026] First, the principles of mechanics and thermodynamics are used to calculate the heat input, heat conduction, thermal expansion, contraction and residual stress generated during welding, and then the welding deformation between different parts is estimated. The estimated welding deformation is compared with the small deformation welding area, medium deformation welding area and large deformation welding area. The welding deformation generated by welding between different parts is divided into small deformation welding area, medium deformation welding area and large deformation welding area. The overall rigidity of the weld is increased in the small deformation welding area and the large deformation welding area. An anti-deformation device is set on one side of the part in the medium deformation welding area. The small deformation welding area is welded first, then the medium deformation welding area is welded, and finally the large deformation welding area is welded to reduce the overall welding deformation. After changing the welding sequence between the parts as mentioned above, the overall rigidity of the weld is used to resist the welding deformation as much as possible, thereby effectively reducing the welding deformation. This solves the problem that multiple adjustments of many materials may reduce the accuracy of welding parameters, and ultimately lead to an increase in the welding deformation of large assembly parts. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to facilitate understanding by those skilled in the art, the present invention is further described below with reference to the accompanying drawings.

[0028] Figure 1 It is a schematic diagram of the non-indentation spot welding of automobile parts of the present invention.

[0029] Description of main component symbols:

[0030] In the figure: 1. welding platform; 2. parts; 3. fixture; 4. anti-deformation device. DETAILED DESCRIPTION

[0031] In order to further explain the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the specific implementation methods, structures, features and effects of the present invention are described in detail below in conjunction with the accompanying drawings and preferred embodiments.

[0032] See also Figure 1 This embodiment provides a non-indentation spot welding production process for an automobile component 2, comprising the following steps:

[0033] S1: Using the principles of mechanics and thermodynamics, calculate the heat input, heat conduction, thermal expansion, contraction and residual stress generated during welding, and then estimate the welding deformation between different parts;

[0034] Calculation of heat input:

[0035] First, the energy input during welding needs to be determined, usually calculated through welding current, voltage and welding speed.

[0036] The heat input (Q) can be calculated using the following formula: Q = I × V × v, where I is the current (A), V is the voltage (V), and v is the welding speed (m / min).

[0037] Calculation of heat conduction:

[0038] Heat conduction can be described by Fourier's law: Q = -kA(dT / dx), where k is the thermal conductivity of the material (W / m·K), A is the cross-sectional area (m²), dT is the temperature change (K), and dx is the distance (m). By solving the heat conduction equation, we can understand the distribution and change of temperature during welding.

[0039] Calculation of thermal expansion:

[0040] The thermal expansion of an object can be expressed by the following formula: , where ΔL is the change in length, α is the thermal expansion coefficient of the material (1 / K), is the original length, ΔT is the temperature change. For the welding area, it is necessary to calculate the temperature gradient of the entire weld and the surrounding area to obtain the thermal expansion of each part;

[0041] Calculation of shrinkage:

[0042] The amount of shrinkage is affected by many factors, including welding method, weld form, welding parameters, etc.

[0043] Based on the reference information provided, shrinkage can be calculated using an approximate formula, such as:

[0044] Approximate transverse shrinkage of single V butt weld: y = 1.01e^(0.0464x)

[0045] Approximate transverse shrinkage of double V butt weld: y = 0.908e^(0.0467x)

[0046] Where x is the plate thickness and y is the shrinkage approximation;

[0047] Calculation of residual stress:

[0048] Residual stresses are generated by the uneven thermal expansion and contraction during welding.

[0049] The residual stress can be calculated using the elastic mechanics method. The specific steps are as follows:

[0050] Determine the thermal strain in the weld area (ε = αΔT);

[0051] Due to the constraints in the welding area, the thermal strain cannot be completely released and thus is converted into residual stress (σ);

[0052] Apply Hooke's law (σ = Eε), where E is the elastic modulus of the material;

[0053] Use finite element analysis (FEA) or analytical methods to solve the stress distribution throughout the structure.

[0054] S2: The deformation between 0.1mm and 1mm, the deformation between 1mm and 5mm, and the deformation greater than 5mm are defined as small deformation welding area, medium deformation welding area, and large deformation welding area respectively; this is for large assembly parts, which contain many parts 2, so they are divided into small deformation welding area, medium deformation welding area, and large deformation welding area;

[0055] S3: Compare the estimated welding deformation with the small deformation welding area, medium deformation welding area and large deformation welding area, and divide the welding deformation caused by welding between different parts into small deformation welding area, medium deformation welding area and large deformation welding area; in fact, S1-S3 need to be realized before welding;

[0056] S4: Correct the welding deformation of the small deformation welding area, the medium deformation welding area and the large deformation welding area, increase the overall rigidity of the welding in the small deformation welding area and the large deformation welding area, set an anti-deformation device 4 on one side of the part in the medium deformation welding area, first weld the small deformation welding area, then weld the medium deformation welding area, and finally weld the large deformation welding area to reduce the overall welding deformation. Here, the order of welding the small deformation welding area, the medium deformation welding area and the large deformation welding area cannot be changed. After changing the welding order between the parts in the above way, the overall rigidity of the welding is used to resist the generation of welding deformation as much as possible, thereby effectively reducing the welding deformation.

[0057] The indentation-free spot welding production process is a high-quality welding technology used for welding automotive parts 2. The purpose is to reduce or avoid indentations in the welding area during the welding process, so as to maintain the beauty and performance of the parts 2. In the indentation-free spot welding production process of automotive parts 2, the indentations generated during the welding process are usually reduced or eliminated by accurately controlling the welding parameters and the mechanical behavior during the welding process. Therefore, when spot welding automotive parts 2, in order to ensure the quality, the indentation-free spot welding production process is usually adopted. However, there are some problems with the current indentation-free spot welding production process of automotive parts 2: when spot welding large assembly parts of the main components of the body-in-white, since the large assembly parts are composed of many parts 2, and the parts 2 are overlapped with the rest of the body-in-white on all sides, the accuracy of the control surface is required to be high. In the face of so many parts 2, in order to ensure the accuracy of indentation-free spot welding, it is necessary to adjust the welding parameters according to different parts 2, which requires the equipment to be able to adapt to many materials, and each adjustment of the welding parameters will inevitably be affected by environmental factors. Multiple adjustments for many materials may reduce the accuracy of the welding parameters, and ultimately lead to an increase in the welding deformation of large assembly parts.

[0058] In order to solve the above problems, in this embodiment, the principles of mechanics and thermodynamics are first used to calculate the heat input, heat conduction, thermal expansion, contraction and residual stress generated during the welding process, and then the welding deformation between different parts is estimated, and the estimated welding deformation is compared with the small deformation welding area, the medium deformation welding area and the large deformation welding area. The welding deformation generated by the welding between different parts is divided into a small deformation welding area, a medium deformation welding area and a large deformation welding area, and the overall rigidity of the welding is increased in the small deformation welding area and the large deformation welding area. An anti-deformation device 4 is set on one side of the part in the medium deformation welding area, and the small deformation welding area is welded first, then the medium deformation welding area is welded, and finally the large deformation welding area is welded to reduce the overall welding deformation. After changing the welding sequence between the parts as mentioned above, the overall rigidity of the welding is used to resist the generation of welding deformation as much as possible, thereby effectively reducing the welding deformation, thereby solving the problem that multiple adjustments of many materials may reduce the accuracy of welding parameters, and ultimately lead to an increase in the welding deformation of large assembly parts.

[0059] Since what needs to be welded is a large assembly part with many parts 2, in order to avoid deformation of many parts 2 during welding, in one embodiment, before welding the small deformation welding area in S4, the parts 2 to be welded are fixed on the welding platform 1 by a plurality of clamps 3, and there are a plurality of anti-deformation devices 4, and each anti-deformation device 4 is arranged on the flip arm of the corresponding clamp 3, such as Figure 1 As shown, the anti-deformation device 4 includes a clamping block, which is arranged on the flip arm of the clamp 3. The clamping block is arranged on one side of the part in the medium deformation welding area, and the clamping block is made of strong clamping steel. The strong clamping steel not only has good stability, but also has good welding performance. Therefore, strong clamping steel is used here. The clamping block cooperates with the clamp 3 to limit the movement of the part control surface to reduce the welding deformation. In addition, even if the welding deformation will vary due to the differences between individual parts, the direction of the welding deformation is generally unified. Therefore, the anti-deformation device 4 only needs to act on one side of the part to produce the corresponding effect.

[0060] In addition, since the automobile component 2 itself is easy to deform, and during welding, the component 2 clamped by the clamp 3 will vibrate, in order to avoid this vibration, the only option is to clamp the component 2 firmly. However, when clamping the component 2, if the component 2 is clamped too tightly, it is easy to cause deformation, and clamping it too loosely will affect the welding accuracy. In order to solve this problem, in one embodiment, a gasket for absorbing its own tolerance is provided on the clamping block. The clamping block adjusts its position with the component 2 through the gasket. The absorption tolerance here refers to the ability of the component to withstand a certain error range without affecting the overall performance. The clamping block adjusts its position with the component 2 through the gasket, so that while absorbing its own tolerance, the position of the control surface can be adjusted as needed. The control surface refers to the surface where the component 2 contacts the clamping block.

[0061] In order to ensure that the welding deformation of all parts of the entire large assembly parts can be reduced in S4, in one embodiment, S4 increases the overall rigidity of welding in the small deformation welding area and the large deformation welding area by increasing the number of welds in the small deformation welding area and the large deformation welding area. The increase in the number of welds is on the one hand to increase the overall rigidity of welding. On the other hand, the number of welds in the small deformation welding area in S4 is greater than the number of welds in the large deformation welding area. In this way, the part with small and large overall rigidity of welding can be distinguished by increasing the number of welds. In addition, the part with large overall rigidity of welding is matched in the small deformation welding area, and the part with small overall rigidity of welding is matched in the large deformation welding area.

[0062] Since the order of welding the small deformation welding area, the medium deformation welding area and the large deformation welding area cannot be changed, and the welding operation steps are also different, in one embodiment, when welding the medium deformation welding area in S4, the following steps are included:

[0063] S41: Clean the medium deformation welding area to ensure that there is no oil, rust or other impurities;

[0064] S42: Perform preliminary welding first, starting from the area with less welding difficulty and less stress, starting from the middle and gradually expanding to both sides;

[0065] S43: Weld the main structure and main frame to ensure the stability and strength of the main structure;

[0066] S44: welding of secondary structures;

[0067] S45: Welded connections:

[0068] S46: Perform proper trimming and repair welding on the weld to ensure the weld quality;

[0069] S47: Carry out necessary cooling, heat treatment, grinding and testing to ensure that the welding quality meets the requirements.

[0070] Furthermore, after the anti-deformation device 4 is adopted, when it is used for welding in the factory, the original workers need to receive training and learning, and need to have a further understanding of the anti-deformation device 4 to ensure the accuracy of welding. In this regard, in one embodiment, the adjustment method of the anti-deformation device 4 is the same as the adjustment method of the clamp 3, and the adjustment method is the same as the adjustment of the clamp 3 tooling, which ensures its own ease of use without additional learning costs. The anti-deformation device 4 has a simple structure and strong reliability, and can be modified on the existing clamp 3 tooling with low modification costs. The device is reliable and easy to use.

[0071] Since an anti-deformation device 4 is added to the welding platform 1, it is usually necessary to return the fixture 3 to the fixture factory for modification, and the inventory needs to be prepared in advance, and the modification cost is relatively high. In order to solve this problem, in one embodiment, the anti-deformation device 4 in S4 is designed separately, and the device is designed with adjustable parts, and the installation precision requirement is low. Therefore, the installation and debugging can be completed in the factory during the idle time of the fixture 3, without the need to prepare inventory parts, and the modification cost is greatly reduced.

[0072] The working principle and use process of the present invention:

[0073] Using the principles of mechanics and thermodynamics, the heat input, heat conduction, thermal expansion, contraction and residual stress generated during welding are calculated, and then the welding deformation between different parts is estimated. The estimated welding deformation is compared with the small deformation welding area, medium deformation welding area and large deformation welding area. The welding deformation generated by welding between different parts is divided into small deformation welding area, medium deformation welding area and large deformation welding area. The welding deformation of the medium deformation welding area and the large deformation welding area is increased in the small deformation welding area and the large deformation welding area. The overall rigidity of the weld is corrected. The welding area and the large deformation welding area, an anti-deformation device 4 is set on one side of the part in the medium deformation welding area to correct the medium deformation welding area, first weld the small deformation welding area, then weld the medium deformation welding area, and finally weld the large deformation welding area to reduce the overall welding deformation. The order of welding the small deformation welding area, the medium deformation welding area and the large deformation welding area cannot be changed here. After changing the welding order between the parts in the above way, the rigidity of the weld as a whole is used to resist the generation of welding deformation as much as possible, thereby effectively reducing the welding deformation.

[0074] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technical personnel in this field can make some changes or modify the technical contents disclosed above into equivalent embodiments without departing from the scope of the technical solution of the present invention. However, any brief modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A process for producing spot welding of automobile parts without indentation, characterized in that: The following steps are involved: S1: Using the principles of mechanics and thermodynamics, calculate the heat input, heat conduction, thermal expansion, contraction, and residual stress generated during welding, and then estimate the welding deformation between different parts; S2: The deformation ranges from 0.1mm to 1mm, from 1mm to 5mm, and greater than 5mm are defined as the small deformation welding area, medium deformation welding area, and large deformation welding area respectively; S3: Compare the estimated welding deformation with the small deformation welding area, medium deformation welding area, and large deformation welding area, and divide the welding deformation generated by welding between different parts into the small deformation welding area, medium deformation welding area, and large deformation welding area; S4: Correct the welding deformation of the small deformation welding area, medium deformation welding area and large deformation welding area, increase the overall welding rigidity in the small deformation welding area and large deformation welding area, set an anti-deformation device on one side of the part in the medium deformation welding area, weld the small deformation welding area first, then weld the medium deformation welding area, and finally weld the large deformation welding area to reduce the overall welding deformation; In the step S4, the number of welding points in the small deformation welding area and the large deformation welding area is increased to increase the overall rigidity of the welding in the small deformation welding area and the large deformation welding area; The number of welding points in the welding area with small deformation in S4 is greater than the number of welding points in the welding area with large deformation.

2. The process for producing automobile parts without indentation spot welding according to claim 1, characterized in that: Before welding the small deformation welding area in S4, the parts to be welded are fixed on the welding platform by a plurality of clamps. There are multiple anti-deformation devices, and each anti-deformation device is arranged on the flip arm of the corresponding clamp.

3. The process for producing automobile parts without indentation spot welding according to claim 2, characterized in that: The anti-deformation device includes a clamping block, which is arranged on the flip arm of the clamp. The clamping block is arranged on one side of the part in the medium deformation welding area, and the clamping block is made of strong clamping steel. The clamping block cooperates with the clamp to limit the movement of the part control surface, thereby reducing the welding deformation.

4. The process for producing automobile parts without indentation spot welding according to claim 3, characterized in that: The pressing block is provided with a gasket for absorbing its own tolerance, and the position of the pressing block and the component is adjusted by the gasket.

5. The process for producing automobile parts without indentation spot welding according to claim 1, characterized in that: When welding the medium deformation welding area in S4, the following steps are included: S41: Clean the medium deformation welding area to ensure that there is no oil, rust or other impurities; S42: Perform preliminary welding first, starting from the area with less welding difficulty and less stress, starting from the middle and gradually expanding to both sides; S43: Weld the main structure and the main frame to ensure the stability and strength of the main structure; S44: welding of secondary structures; S45: Welded connections: S46: Perform appropriate repair and repair welding on the welds to ensure weld quality; S47: Carry out necessary cooling, heat treatment, grinding and testing to ensure that the welding quality meets the requirements.

6. The process for producing automobile parts without indentation spot welding according to claim 2, characterized in that: The adjustment method of the anti-deformation device is the same as the adjustment method of the clamp.

7. The process for producing automobile parts with no indentation spot welding according to claim 1, characterized in that: The anti-deformation device in S4 is designed separately and has an adjustable part, so the installation accuracy requirement is relatively low.

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