Steel-steel and aluminum-aluminum resistance spot welding mixed line cross production welding parameter determination system and method and cross production system and method

Abstract

The invention discloses a steel-steel and aluminum-aluminum resistance spot welding mixed-line cross production welding parameter determination system and method and a cross production system and method. The method comprises the following steps: acquiring welding current of aluminum-aluminum resistance spot welding when an aluminum spot welding gun electrode tip is adopted from a historical production database; or the welding current of steel-steel resistance spot welding when the electrode tip of the steel spot welding gun is adopted; correcting the welding current of aluminum-aluminum resistance spot welding when the electrode tip of the aluminum spot welding gun is adopted, and determining corrected data as the welding current of aluminum-aluminum resistance spot welding when the electrode tip of the steel spot welding gun is adopted, or correcting the welding current of steel-steel resistance spot welding when the electrode tip of the steel spot welding gun is adopted; and determining the corrected data as the welding current of steel-steel resistance spot welding when the aluminum spot welding gun electrode tip is adopted. By means of the mixed wire cross production method, steel-steel and aluminum-aluminum resistance spot welding low-cost mixed wire and cross production is achieved, and the welding spot quality of steel-steel and aluminum-aluminum resistance spot welding mixed wire production is guaranteed.

Description

Technical Field

[0001] The present invention relates to the field of welding technology, and in particular to a system and method for determining welding parameters in mixed-line cross production of steel-steel and aluminum-aluminum resistance spot welding, and a cross production system and method. Background Art

[0002] Resistance spot welding is the most commonly used connection technology on car bodies due to its low cost and high efficiency. Resistance spot welding is often used in the automotive manufacturing field to connect steel to steel and aluminum to aluminum. At present, the resistance spot welding technology for steel to steel is relatively mature, but aluminum alloy has the characteristics of dense surface oxide layer, low melting point, high linear expansion rate, high conductivity, and easy alloy reaction with copper, which often has special requirements for resistance spot welding electrode heads.

[0003] Due to the relevant characteristics of aluminum-aluminum resistance spot welding, the automotive industry is currently unable to use conventional aluminum welding guns to achieve low-cost mixed-line cross-production of "steel-steel" and "aluminum-aluminum" resistance spot welding.

[0004] DeltaSpot resistance spot welding technology is to add an electrode belt to the electrode. During welding, the electrode does not directly contact the base material, but the electrode belt contacts the base material to achieve welding. After each weld is completed, the electrode belt will automatically move to the next position, so that the residue after each aluminum spot welding or steel spot welding process will not affect the next resistance spot welding process, thereby ensuring high-quality mixed-line production of "steel-steel" and "aluminum-aluminum" resistance spot welding. DeltaSpot resistance spot welding technology requires a new electrode belt position for each weld, and the electrode belt needs to be replaced after use. Its production cost is higher than the conventional grinding electrode head method.

[0005] FAW Zhou Linzhu, Hao Gu, Ying Cui, et al. "A common electrode cap and welding method for steel-steel and aluminum-aluminum resistance spot welding. Mechanical and Electronic Control Engineering, 2023" By designing a special-shaped electrode cap, when welding aluminum parts, the presence of the head arc surface will make the electrode cap gradually increase the contact with the welding position in a stepless progressive manner, and the parts are gradually squeezed. At this time, the surface oxide layer can be squeezed to the outside, eliminating the oxide layer, which is conducive to the formation of weld nuggets, ensuring the structural strength of the electrode cap while meeting the high pressure required for aluminum spot welding. At the same time, the welding contact surface is smaller than the large electrode cap of the aluminum spot welding plane, which can realize steel resistance spot welding. The structure and composition of the special-shaped electrode cap used by FAW are inconsistent with the conventional Cu-Cr-Zr electrode, and it does not provide the relationship between the welding parameters of steel-steel when using the special-shaped electrode cap and the welding parameters of steel-steel when using the conventional Cu-Cr-Zr electrode head. Moreover, the electrode cap is a customized product and is relatively expensive. It also requires a large amount of modification to conventional general welding equipment such as resistance spot welding guns, and the cost of production line modification is high, making it impossible to achieve low-cost mixed-line cross-production of "steel-steel" and "aluminum-aluminum" resistance spot welding. Summary of the invention

[0006] The purpose of the present invention is to solve the problem that it is difficult to achieve high-quality mixed-line production and low-cost production in the mixed-line production process of "steel-steel" and "aluminum-aluminum" resistance spot welding in the prior art, and thus propose a steel-steel, aluminum-aluminum resistance spot welding mixed-line cross production welding parameter determination system and method, and a cross production system and method. The method of the present invention first determines the welding current of steel-steel resistance spot welding when using an aluminum welding gun based on the known conventional steel-steel resistance spot welding welding current and the set related parameters, and uses the aluminum welding gun to perform aluminum-aluminum spot welding and steel-steel spot welding respectively. When the number of welding points of aluminum-aluminum spot welding and the number of welding points of steel-steel spot welding reach the preset conditions, the next cycle of aluminum-aluminum spot welding and steel-steel spot welding is performed, otherwise, the electrode head of the aluminum welding gun is ground and then welding is continued. The method of the present invention can realize the mixed-line cross production of steel-steel and aluminum-aluminum resistance spot welding using conventional spot welding equipment, and at the same time ensures the quality of welding points in the mixed-line production of steel-steel and aluminum-aluminum spot welding.

[0007] To achieve this purpose, a first aspect of the present invention is a steel-steel, aluminum-aluminum resistance spot welding mixed line cross production welding parameter determination system, which includes a first welding parameter acquisition module, a second welding parameter determination module;

[0008] The first welding parameter acquisition module is used to acquire the welding current of aluminum-aluminum resistance spot welding when an aluminum spot welding gun electrode head is used, or the welding current of steel-steel resistance spot welding when a steel spot welding gun electrode head is used from the historical production database;

[0009] The second welding parameter determination module corrects the welding current of aluminum-aluminum resistance spot welding when using an aluminum spot welding gun electrode head, and determines the corrected data as the welding current of aluminum-aluminum resistance spot welding when using a steel spot welding gun electrode head, or corrects the welding current of steel-steel resistance spot welding when using a steel spot welding gun electrode head, and determines the corrected data as the welding current of steel-steel resistance spot welding when using an aluminum spot welding gun electrode head.

[0010] Preferably, the welding current of steel-steel resistance spot welding when using a steel spot welding gun electrode head is corrected using the correction coefficient and the fluctuation range of the welding current, and the corrected data is determined as the welding current of steel-steel resistance spot welding when using an aluminum spot welding gun electrode head.

[0011] More preferably, the calculation formula for correcting the welding current of steel-steel resistance spot welding when the steel spot welding gun electrode tip is used is as follows:

[0012] I 2 =A×I 1 +B (1)

[0013] In the formula, I 2 is the welding current of steel-steel resistance spot welding when using aluminum spot welding gun electrode tip, A is the correction factor, I 1 is the welding current of steel-steel resistance spot welding when using a steel spot welding gun electrode tip, and B is the fluctuation range of the welding current obtained based on the welding specimen test.

[0014] Further preferably, the correction coefficient is calculated according to the loss ratio of resistance spot welding heat by different welding gun electrode heads and the loss ratio of resistance spot welding heat by cooling water flow when using different welding guns, and the calculation formula is as follows:

[0015]

[0016] In the formula, A is the correction coefficient, k1 is the ratio of heat loss of resistance spot welding caused by different welding gun electrode heads, and k2 is the ratio of heat loss of resistance spot welding caused by different welding gun cooling water flow rates.

[0017] More preferably, the heat loss ratio of different welding gun electrode heads to resistance spot welding is calculated according to the contact area between the aluminum spot welding gun electrode head and the steel spot welding gun electrode head and the plate to be tested under a fixed pressure, and the calculation formula is as follows:

[0018] k1=S1 / S2 (3)

[0019] Where, k1 is the ratio of heat loss of different welding gun electrode heads to resistance spot welding, S1 is the contact area corresponding to the aluminum spot welding gun electrode head, and S2 is the contact area corresponding to the steel spot welding gun electrode head;

[0020] According to the inner surface temperature of the electrode rod under the water flow rate when using a steel spot welding gun and the water flow rate when using an aluminum spot welding gun, the proportion of the cooling water flow rate of different welding guns to the heat loss of resistance spot welding is calculated. The calculation formula is as follows:

[0021] k2=(T 2 -298) / (T 1 -298) (4)

[0022] Where k2 is the ratio of the cooling water flow rate of different welding guns to the heat loss of resistance spot welding, T 1 is the inner surface temperature of the electrode rod under water flow when using a steel spot welding gun, T 2 It is the inner surface temperature of the electrode rod under water flow rate when using an aluminum spot welding gun.

[0023] A method for determining welding parameters for mixed-line cross production of steel-steel and aluminum-aluminum resistance spot welding designed in the second aspect of the present invention comprises the following steps:

[0024] Obtaining from the historical production database the welding current of aluminum-aluminum resistance spot welding when an aluminum spot welding gun electrode tip is used, or the welding current of steel-steel resistance spot welding when a steel spot welding gun electrode tip is used;

[0025] The welding current of aluminum-aluminum resistance spot welding when using an aluminum spot welding gun electrode head is corrected, and the corrected data is determined as the welding current of aluminum-aluminum resistance spot welding when using a steel spot welding gun electrode head, or the welding current of steel-steel resistance spot welding when using a steel spot welding gun electrode head is corrected, and the corrected data is determined as the welding current of steel-steel resistance spot welding when using an aluminum spot welding gun electrode head.

[0026] A steel-steel and aluminum-aluminum resistance spot welding mixed-line cross production system designed in the third aspect of the present invention comprises a welding cycle judgment module, the first welding parameter acquisition module mentioned above, and a second welding parameter determination module;

[0027] The welding cycle judgment module uses the aluminum spot welding gun electrode head to perform steel-steel spot welding under the determined welding current of steel-steel resistance spot welding when the aluminum spot welding gun electrode head is used, and uses the aluminum spot welding gun electrode head to perform aluminum-aluminum spot welding under the acquired welding current of aluminum-aluminum resistance spot welding when the aluminum spot welding gun electrode head is used;

[0028] or using the steel spot welding gun electrode tip to perform aluminum-aluminum spot welding at the determined welding current of aluminum-aluminum resistance spot welding when using the steel spot welding gun electrode tip, and using the steel spot welding gun electrode tip to perform steel-steel spot welding at the obtained welding current of steel-steel resistance spot welding when using the steel spot welding gun electrode tip;

[0029] When the number of welds of aluminum-aluminum spot welding and the number of welds of steel-steel spot welding reach the preset conditions, the next cycle of aluminum-aluminum spot welding and steel-steel spot welding is carried out; otherwise, the electrode tip of the aluminum spot welding gun is ground before continuing the next cycle of aluminum-aluminum spot welding and steel-steel spot welding.

[0030] Preferably, when the number of welds of aluminum-aluminum spot welding and the number of welds of steel-steel spot welding reach a preset condition, the calculation formulas for the next cycle of aluminum-aluminum spot welding and steel-steel spot welding are as follows:

[0031]

[0032] In the formula, m i is the number of welding points of the i-th aluminum-aluminum spot welding, n i is the number of welds in the i-th steel-steel spot welding, l is the total number of cycles, K is the number of welds of aluminum obtained by the mixed line cycle production of steel-steel and aluminum-aluminum resistance spot welding, and Q is the number of welds of steel obtained by steel-steel resistance spot welding.

[0033] More preferably, the value of K is determined by: using the aluminum spot welding gun electrode head to perform steel-steel and aluminum-aluminum resistance spot welding cycle production until the welds of the steel-steel resistance spot welding do not meet the steel spot welding conditions or the welds of the aluminum-aluminum resistance spot welding do not meet the aluminum spot welding conditions, and the cycle is stopped, and the total number of aluminum welds that meet the aluminum spot welding conditions during the cycle production process is counted as K;

[0034] The method for obtaining the value of Q is: using the aluminum spot welding gun electrode head to perform steel-steel resistance spot welding production until the welds of the steel-steel resistance spot welding do not meet the steel spot welding conditions, and the total number of steel welds that meet the steel spot welding conditions during the production process is counted as Q.

[0035] A steel-steel, aluminum-aluminum resistance spot welding mixed line cross production method designed in the fourth aspect of the present invention comprises the following:

[0036] Obtaining from the historical production database the welding current of aluminum-aluminum resistance spot welding when an aluminum spot welding gun electrode tip is used, or the welding current of steel-steel resistance spot welding when a steel spot welding gun electrode tip is used;

[0037] Correcting the welding current of aluminum-aluminum resistance spot welding when an aluminum spot welding gun electrode tip is used, and determining the corrected data as the welding current of aluminum-aluminum resistance spot welding when a steel spot welding gun electrode tip is used, or correcting the welding current of steel-steel resistance spot welding when a steel spot welding gun electrode tip is used, and determining the corrected data as the welding current of steel-steel resistance spot welding when an aluminum spot welding gun electrode tip is used;

[0038] Using the aluminum spot welding gun electrode tip to perform steel-steel spot welding at the determined welding current of steel-steel resistance spot welding when using the aluminum spot welding gun electrode tip, and using the aluminum spot welding gun electrode tip to perform aluminum-aluminum spot welding at the acquired welding current of aluminum-aluminum resistance spot welding when using the aluminum spot welding gun electrode tip;

[0039] or using the steel spot welding gun electrode tip to perform aluminum-aluminum spot welding at the determined welding current of aluminum-aluminum resistance spot welding when using the steel spot welding gun electrode tip, and using the steel spot welding gun electrode tip to perform steel-steel spot welding at the obtained welding current of steel-steel resistance spot welding when using the steel spot welding gun electrode tip;

[0040] When the number of welds of aluminum-aluminum spot welding and the number of welds of steel-steel spot welding reach the preset conditions, the next cycle of aluminum-aluminum spot welding and steel-steel spot welding is carried out; otherwise, the electrode tip of the aluminum spot welding gun is ground before continuing the next cycle of aluminum-aluminum spot welding and steel-steel spot welding.

[0041] Beneficial effects of the present invention:

[0042] (1) The present invention determines the welding current of steel-steel resistance spot welding when an aluminum welding gun is used based on the known conventional welding current of steel-steel resistance spot welding and the set related parameters. When welding conventional multi-layer steel plates for automobiles (total plate thickness ≤ 10 mm), an aluminum welding gun with a larger electrode end face diameter (7-14 mm) can be directly used, and at the end of welding, a weld with mechanical properties similar to or better than that when a conventional "steel-steel spot welding" welding gun (whose electrode end face diameter is 5-7 mm and an electrode head made of conventional materials) is used can be obtained;

[0043] (2) The steel-steel and aluminum-aluminum resistance spot welding mixed line and cross production method described in the present invention not only solves the problem in the prior art that conventional spot welding equipment cannot be used to achieve low-cost mixed line and cross production of steel-steel and aluminum-aluminum resistance spot welding, but also ensures the quality of welds produced by steel-steel and aluminum-aluminum spot welding mixed lines. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 It is a structural block diagram of a welding parameter determination system for mixed-line cross production of steel-steel and aluminum-aluminum resistance spot welding according to one embodiment of the present invention;

[0045] Figure 2 It is a structural block diagram of a steel-steel and aluminum-aluminum resistance spot welding mixed-line cross production system according to one embodiment of the present invention;

[0046] Figure 3 This is a schematic diagram of the steel plate structure of steel-steel spot welding in Example 1 of the present invention;

[0047] Figure 4A schematic flow chart of a method for determining welding parameters for mixed-line cross production of steel-steel and aluminum-aluminum resistance spot welding according to an embodiment of the present invention;

[0048] Figure 5 The figure is a flow chart of a welding cycle determination module according to an embodiment of the present invention. DETAILED DESCRIPTION

[0049] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments:

[0050] Resistance spot welding is commonly used in the automotive manufacturing field to connect steel to steel and aluminum to aluminum, which is usually called steel-steel and aluminum-aluminum resistance spot welding. During welding, steel-steel resistance spot welding uses a steel spot welding gun electrode tip, and aluminum-aluminum resistance spot welding uses an aluminum spot welding gun electrode tip. The electrode tips for these two types of welding are made of Cu-Cr-Zr, and the sizes of the two electrode tips are different. Therefore, they cannot be simply used for mixed-line cross production of steel-steel and aluminum-aluminum resistance spot welding. The present invention proposes to use one of the electrode heads for steel-steel and aluminum-aluminum resistance spot welding cross production suitable for this scenario, such as using an electrode head suitable for steel-steel for steel-steel resistance spot welding, using known welding parameters for welding, and when using the steel-steel electrode head for aluminum-aluminum resistance spot welding, by correcting the welding parameters of steel-steel resistance spot welding, using the corrected welding parameters for aluminum-aluminum resistance spot welding, thereby realizing steel-steel and aluminum-aluminum resistance spot welding mixed-line cross production welding without changing equipment and materials; or using an electrode head suitable for aluminum-aluminum for aluminum-aluminum resistance spot welding, using known welding parameters for welding, and when using the aluminum-aluminum electrode head for steel-steel resistance spot welding, by correcting the welding parameters of aluminum-aluminum resistance spot welding, using the corrected welding parameters for steel-steel resistance spot welding, thereby realizing steel-steel and aluminum-aluminum resistance spot welding mixed-line cross production welding without changing equipment and materials.

[0051] Specifically, it relates to a control system for resistance welding, and in particular to a software control part in the control system.

[0052] Example 1

[0053] A system for determining welding parameters for steel-steel and aluminum-aluminum resistance spot welding mixed-line cross production, such as Figure 1 As shown, it includes a first welding parameter acquisition module and a second welding parameter determination module;

[0054] The first welding parameter acquisition module is used to acquire the welding current of aluminum-aluminum resistance spot welding when an aluminum spot welding gun electrode head is used, or the welding current of steel-steel resistance spot welding when a steel spot welding gun electrode head is used from the historical production database;

[0055] The second welding parameter determination module corrects the welding current of aluminum-aluminum resistance spot welding when using an aluminum spot welding gun electrode head, and determines the corrected data as the welding current of aluminum-aluminum resistance spot welding when using a steel spot welding gun electrode head, or corrects the welding current of steel-steel resistance spot welding when using a steel spot welding gun electrode head, and determines the corrected data as the welding current of steel-steel resistance spot welding when using an aluminum spot welding gun electrode head.

[0056] In this article, the historical production database refers to the welding tensile test results conducted on historical models.

[0057] In this article, the welding current of steel-steel resistance spot welding when using a steel spot welding gun electrode head is the welding current of steel-steel resistance spot welding using an electrode head of conventional materials (such as a Cu-Cr-Zr electrode head) and a welding gun for "steel-steel spot welding" with an electrode head end face diameter of 5 to 7 mm; the welding current of aluminum-aluminum resistance spot welding when using an aluminum spot welding gun electrode head is the welding current of aluminum-aluminum spot welding using an electrode head of conventional materials (such as a Cu-Cr-Zr electrode head) and a welding gun for "aluminum-aluminum spot welding" with an electrode head end face diameter of 7 to 14 mm.

[0058] In the above technical solution, the welding current of steel-steel resistance spot welding when using a steel spot welding gun electrode head is corrected using the correction coefficient and the fluctuation range of the welding current, and the corrected data is determined as the welding current of steel-steel resistance spot welding when using an aluminum spot welding gun electrode head.

[0059] In the above technical solution, the calculation formula for correcting the welding current of steel-steel resistance spot welding when the steel spot welding gun electrode tip is used is as follows:

[0060] I 2 =A×I 1 +B (1)

[0061] In the formula, I 2 is the welding current of steel-steel resistance spot welding when using aluminum spot welding gun electrode tip, A is the correction factor, I 1 is the welding current of steel-steel resistance spot welding when using a steel spot welding gun electrode tip, and B is the fluctuation range of the welding current obtained based on the welding specimen test.

[0062] In the above technical solution, the value of A is based on the finite element analysis and heat transfer analysis to estimate the ratio of the heat loss of resistance spot welding due to a larger electrode end face diameter (the end face diameter of the electrode head of an aluminum spot welding gun is larger than that of the electrode head of a steel spot welding gun) and a larger welding gun cooling water flow rate (the water flow rate of an aluminum spot welding gun is larger than that of a steel spot welding gun), and the square root thereof is taken to obtain the initial value A. Specifically, the correction coefficient is calculated according to the ratio of the heat loss of resistance spot welding due to different welding gun electrode heads and the ratio of the heat loss of resistance spot welding due to the cooling water flow rate when using different welding guns. The calculation formula is as follows:

[0063]

[0064] In the formula, A is the correction coefficient, k1 is the ratio of heat loss of resistance spot welding caused by different welding gun electrode heads, and k2 is the ratio of heat loss of resistance spot welding caused by different welding gun cooling water flow rates.

[0065] In the above technical solution, the loss ratio of the resistance spot welding heat of different welding gun electrode heads is calculated according to the contact area between the aluminum spot welding gun electrode head and the steel spot welding gun electrode head and the plate to be tested under a fixed pressure, and the calculation formula is as follows:

[0066] k1=S1 / S2 (3)

[0067] Where k1 is the ratio of heat loss of different welding gun electrode heads to resistance spot welding, S1 is the contact area corresponding to the aluminum spot welding gun electrode head, and S2 is the contact area corresponding to the steel spot welding gun electrode head. In this article, the contact area corresponding to the aluminum spot welding gun electrode head and the contact area corresponding to the steel spot welding gun electrode head are obtained using finite element analysis. Fixed pressure refers to the welding pressure given in the welding parameters, which has different values ​​depending on the welding plate group, for example, its value range can be 0.98~5.88kN.

[0068] In the above technical solution, the ratio of the cooling water flow rate of different welding guns to the heat loss of resistance spot welding is calculated according to the inner surface temperature of the electrode rod under the water flow rate when using a steel spot welding gun and the water flow rate when using an aluminum spot welding gun. The calculation formula is as follows:

[0069] k2=(T 2 -298) / (T 1 -298) (4)

[0070] Where k2 is the ratio of the cooling water flow rate of different welding guns to the heat loss of resistance spot welding, T 1 is the inner surface temperature of the electrode rod under water flow when using a steel spot welding gun, T 2is the inner surface temperature of the electrode rod under water flow rate when using aluminum spot welding gun. In this paper, the inner surface temperature of the electrode rod under water flow rate when using steel spot welding gun and the inner surface temperature of the electrode rod under water flow rate when using aluminum spot welding gun are obtained by finite element analysis.

[0071] The above technical solution also includes verifying the correction coefficient A, using A*I 1 The specific method for verifying the steel-steel resistance spot welding experiment is: a tensile test is performed after welding to confirm whether the weld strength and weld core diameter meet the standard requirements. Specifically, the weld core diameter Where t is the thickness of the thinnest plate in the welded plate group, and the weld strength is 2 to 28 kN. In this paper, the value of A is 1 to 2.

[0072] In the above technical solution, B is the fluctuation range of the welding current obtained according to the welding test piece test. For example, when the welding current A×I 1 =11kA, conduct welding experiments at 10, 10.5, 11, 11.5, and 12kA. Assuming that the welding tensile test at currents of 10 to 12kA meets the requirements, then B can be -1 to 1. In this article, the value of B is -1 to 1kA.

[0073] The welding current I of steel-steel resistance spot welding using the aluminum spot welding gun electrode tip determined by the above steps is 2 When welding conventional multi-layer steel plates for automobiles (total plate thickness ≤ 10 mm), an aluminum spot welding gun with a larger electrode end face diameter can be directly used, for example, an aluminum welding gun with an electrode head end face diameter of 7 to 14 mm can be used. At the end of welding, a weld with mechanical properties similar to or better than that obtained when using a conventional "steel-steel spot welding" welding gun (whose electrode end face diameter is 5 to 7 mm and uses an electrode head made of conventional materials) can be obtained.

[0074] Example 2

[0075] A method for determining welding parameters for mixed-line cross production of steel-steel and aluminum-aluminum resistance spot welding, such as Figure 4 As shown, it includes the following:

[0076] Obtaining from the historical production database the welding current of aluminum-aluminum resistance spot welding when an aluminum spot welding gun electrode tip is used, or the welding current of steel-steel resistance spot welding when a steel spot welding gun electrode tip is used;

[0077] The welding current of aluminum-aluminum resistance spot welding when using an aluminum spot welding gun electrode head is corrected, and the corrected data is determined as the welding current of aluminum-aluminum resistance spot welding when using a steel spot welding gun electrode head, or the welding current of steel-steel resistance spot welding when using a steel spot welding gun electrode head is corrected, and the corrected data is determined as the welding current of steel-steel resistance spot welding when using an aluminum spot welding gun electrode head.

[0078] Example 3

[0079] A steel-steel, aluminum-aluminum resistance spot welding mixed line cross production system, such as Figure 2 As shown, it includes a welding cycle judgment module, the first welding parameter acquisition module mentioned above, and a second welding parameter determination module;

[0080] The welding cycle judgment module uses the aluminum spot welding gun electrode head to perform steel-steel spot welding under the determined welding current of steel-steel resistance spot welding when the aluminum spot welding gun electrode head is used, and uses the aluminum spot welding gun electrode head to perform aluminum-aluminum spot welding under the acquired welding current of aluminum-aluminum resistance spot welding when the aluminum spot welding gun electrode head is used;

[0081] or using the steel spot welding gun electrode tip to perform aluminum-aluminum spot welding at the determined welding current of aluminum-aluminum resistance spot welding when using the steel spot welding gun electrode tip, and using the steel spot welding gun electrode tip to perform steel-steel spot welding at the obtained welding current of steel-steel resistance spot welding when using the steel spot welding gun electrode tip;

[0082] When the number of welds of aluminum-aluminum spot welding and the number of welds of steel-steel spot welding reach the preset conditions, the next cycle of aluminum-aluminum spot welding and steel-steel spot welding is carried out; otherwise, the electrode tip of the aluminum spot welding gun is ground before continuing the next cycle of aluminum-aluminum spot welding and steel-steel spot welding.

[0083] In the above technical solution, when the number of welds of aluminum-aluminum spot welding and the number of welds of steel-steel spot welding reach the preset conditions, the calculation formulas for the next cycle of aluminum-aluminum spot welding and steel-steel spot welding are as follows:

[0084]

[0085] In the formula, m i is the number of welding points of the i-th aluminum-aluminum spot welding, n i is the number of welds of the i-th steel-steel spot welding, l is the total number of cycles, K is the number of welds of aluminum obtained by the mixed-line cycle production of steel-steel and aluminum-aluminum resistance spot welding, and Q is the number of welds of steel obtained by the steel-steel resistance spot welding production. In this paper, only when equation (5) and equation (6) are satisfied at the same time, can the next cycle of aluminum-aluminum spot welding and steel-steel spot welding be carried out. Otherwise, if only one of equation (5) or equation (6) is satisfied, it is also necessary to grind the electrode tip of the aluminum welding gun before continuing the next cycle of aluminum-aluminum spot welding and steel-steel spot welding.

[0086] In the above technical scheme, the value of K is obtained as follows: the aluminum spot welding gun electrode head is used to perform steel-steel and aluminum-aluminum resistance spot welding cycle production until the welds of the steel-steel resistance spot welding do not meet the steel spot welding conditions or the welds of the aluminum-aluminum resistance spot welding do not meet the aluminum spot welding conditions, and the cycle is stopped, and the total number of aluminum welds that meet the aluminum spot welding conditions during the cycle production process is counted as K. In this article, the aluminum spot welding conditions refer to the weld core diameter reaching 4 to 15 mm and the weld strength reaching 1 to 25 kN. Specifically, for example, using an aluminum spot welding gun, first weld 3 aluminum points and then weld 5 steel points, then weld 3 aluminum points and then weld 5 steel points, and cycle in sequence until the aluminum welds are qualified in the 6th cycle and the steel welds are unqualified. Then the number of qualified aluminum spot welding in the process is accumulated, and the value obtained is the K value under the cycle of 3 aluminum + 5 steel, that is, K is 15.

[0087] In the above technical solution, the method for taking the value of Q is: using the aluminum spot welding gun electrode head to perform steel-steel resistance spot welding production until the welds of the steel-steel resistance spot welding do not meet the steel spot welding conditions, and the total number of steel welds that meet the steel spot welding conditions during the production process is counted as Q.

[0088] In this article, aluminum-aluminum workpieces are continuously welded using an aluminum spot welding gun. After welding to the K+1th point, the aluminum-aluminum workpiece weld does not meet the aluminum spot welding conditions, and the Kth weld is the maximum value of K; aluminum-steel workpieces are continuously welded using an aluminum spot welding gun. After welding to the Q+1th point, the steel-steel workpiece weld does not meet the steel spot welding conditions, and the Qth weld is the maximum value of Q. The maximum values ​​of K and Q are to guide the values ​​of K and Q in the steel-steel and aluminum-aluminum resistance spot welding cycle production. Specifically, when the maximum value of K is known, it can guide the technicians on how many test pieces to be welded need to be prepared during the experiment.

[0089] In actual mass production, in order to ensure the production rhythm, combined with the test value K is generally taken as ≥15, and Q is generally taken as ≥150. However, considering that other people do not consider the rhythm, using a K value of <15 (such as K=5, only 1 aluminum-aluminum spot welding and 5 steel-steel spot welding are performed in each cycle, and grinding is performed after 5 cycles) can also achieve steel-steel and aluminum-aluminum mixed line welding production. Therefore, it is recommended that the K value range can be set to 0-50 and the Q value range can be set to 0-200.

[0090] The welding cycle judgment module is used to judge when the electrode tip should be ground during the steel-steel and aluminum-aluminum mixed line production process, so as to ensure that the mechanical properties of the weld, the core diameter of the weld and the quality of the weld meet the standard requirements. In this article, the specific method of electrode tip grinding is: grinding the electrode tip diameter to 7-14mm, and the surface is flat and free of attachments.

[0091] Example 4

[0092] A steel-steel, aluminum-aluminum resistance spot welding mixed line cross production method, which includes the following:

[0093] like Figure 4 As shown, the welding current of aluminum-aluminum resistance spot welding when an aluminum spot welding gun electrode head is used, or the welding current of steel-steel resistance spot welding when a steel spot welding gun electrode head is used is obtained from the historical production database;

[0094] Correcting the welding current of aluminum-aluminum resistance spot welding when an aluminum spot welding gun electrode tip is used, and determining the corrected data as the welding current of aluminum-aluminum resistance spot welding when a steel spot welding gun electrode tip is used, or correcting the welding current of steel-steel resistance spot welding when a steel spot welding gun electrode tip is used, and determining the corrected data as the welding current of steel-steel resistance spot welding when an aluminum spot welding gun electrode tip is used;

[0095] like Figure 5 As shown, the aluminum spot welding gun electrode head is used to perform steel-steel spot welding under the determined welding current of steel-steel resistance spot welding when the aluminum spot welding gun electrode head is used, and the aluminum spot welding gun electrode head is used to perform aluminum-aluminum spot welding under the obtained welding current of aluminum-aluminum resistance spot welding when the aluminum spot welding gun electrode head is used;

[0096] or using the steel spot welding gun electrode tip to perform aluminum-aluminum spot welding at the determined welding current of aluminum-aluminum resistance spot welding when using the steel spot welding gun electrode tip, and using the steel spot welding gun electrode tip to perform steel-steel spot welding at the obtained welding current of steel-steel resistance spot welding when using the steel spot welding gun electrode tip;

[0097] When the number of welds of aluminum-aluminum spot welding and the number of welds of steel-steel spot welding reach the preset conditions, the next cycle of aluminum-aluminum spot welding and steel-steel spot welding is carried out; otherwise, the electrode tip of the aluminum spot welding gun is ground before continuing the next cycle of aluminum-aluminum spot welding and steel-steel spot welding.

[0098] Example 5

[0099] Welding parameter determination module:

[0100] right Figure 3 The three-layer plate shown is subjected to steel-steel welding, and the three-layer plate comprises: plate 1 is a bake-hardened steel with a thickness of 0.65 mm, and its grade is CR140BH; plate 2 is a dual-phase steel with a thickness of 2.0 mm, and its grade is DP980; plate 3 is a bake-hardened steel with a thickness of 1.4 mm, and its grade is CR140BH;

[0101] The welding equipment adopts a medium frequency DC spot welding machine, and its electrode head material is Cu-Cr-Zr. When the electrode head and the end face diameter of the electrode head made of conventional Cu-Cr-Zr material are confirmed to be 6 mm by a method known in the industry, the welding parameters of each of the above-mentioned multiple plates are: the welding pressure can be 3.43 kN, the welding current can be 8.5 kA, the welding time can be 400 ms, the pre-pressing time before welding can be 80 ms, the cooling water flow rate of the welding gun can be 4 L / min, the positive tensile force of the weld joint of 0.65 mm bake hardened steel and 2.0 mm duplex steel is 3.95 ± 0.12 kN, and the positive tensile force of the weld joint of 2.0 mm duplex steel and 1.4 mm bake hardened steel is 11.82 ± 0.1 kN;

[0102] The electrode end face of the aluminum welding gun is 8 mm, the cooling water flow rate is 12 L / min, and the correction coefficient A=1.12, B=±0.3 kA. The welding parameters of the above-mentioned multiple steel plates using the aluminum welding gun can be determined as follows: welding pressure is 3.43 kN, welding current is 9.3-9.8 kA, welding time is 400 ms, pre-pressing time before welding is 80 ms, welding gun cooling water flow rate is 12 L / min, the positive tensile force of the weld joint of 0.65 mm bake hardened steel and 2.0 mm dual-phase steel is 4.17±0.09 kN, and the positive tensile force of the weld joint of 2.0 mm dual-phase steel and 1.4 mm bake hardened steel is 12.07±0.19kN; by comparison, it is not difficult to see that when welding is carried out using a steel spot welding gun, the weld strength of plate 1 and plate 2 is 3.95±0.12kN, and when welding is carried out using an aluminum spot welding gun, the weld strength of plate 1 and plate 2 is 4.17±0.09kN. It is not difficult to see that the mechanical properties of the latter are similar to or better than those of the former. After the welding parameters are determined by the present invention, a steel-steel plate group is spot welded using an aluminum spot welding gun with an electrode end face diameter of 7-14mm, and a weld with mechanical properties similar to or better than that of steel-steel spot welding using a welding gun with an electrode end face diameter of 5-7mm can be obtained.

[0103] Welding cycle judgment module:

[0104] First, aluminum-aluminum spot welding was performed three times, the plate group of which was 0.9 mm HA5754 and 1.2 mm HA5754, and the welding parameters of aluminum-aluminum spot welding using the aluminum welding gun were as follows: the electrode end face of the aluminum-aluminum spot welding gun was 8 mm, the cooling water flow rate was 12 L / min, the welding pressure was 2.94 kN, the welding current was 26 kA, the welding time was 100 ms, and the pre-pressing time before welding was 60 ms;

[0105] Then four steel-steel spot weldings were performed, and the welded plate set was Figure 3 The three-layer plate shown is spot welded steel-steel using an aluminum welding gun with an electrode end face of 8 mm, and the welding parameters are as described above;

[0106] K is 15, Q is 150, and after the fourth cycle,

[0107]

[0108] Therefore, the next spot welding cycle can be continued directly, and the electrode tip of the aluminum spot welding gun does not need to be ground. After the 5th cycle,

[0109]

[0110] At this time, the electrode tip of the aluminum spot welding gun should be ground before a new cycle of spot welding is carried out.

[0111] In this example, specific values ​​are assigned to the number of aluminum-aluminum spot welds and the number of steel-steel spot welds. However, in the mixed-line cross-production of "steel-steel" and "aluminum-aluminum" spot welding, it is not required that the number of aluminum-aluminum spot welds in a certain cycle is equal to the number of aluminum-aluminum spot welds in the next cycle, nor is it required that the number of steel-steel spot welds in a certain cycle is equal to the number of steel-steel spot welds in the next cycle.

[0112] The present invention determines the welding current of steel-steel resistance spot welding when an aluminum welding gun is used according to the known conventional welding current of steel-steel resistance spot welding and set related parameters. When welding conventional multi-layer steel plates for automobiles (total plate thickness ≤10mm), an aluminum welding gun with a larger electrode end face diameter (7-14mm) can be directly used, and at the end of welding, a weld with mechanical properties similar to or better than that when a conventional "steel-steel spot welding" welding gun (whose electrode end face diameter is 5-7mm and an electrode head made of conventional materials) is used can be obtained. This solves the problem in the prior art that conventional spot welding equipment cannot be used to achieve low-cost mixed-line and cross-production of steel-steel and aluminum-aluminum resistance spot welding, and ensures the quality of welds produced by mixed-line steel-steel and aluminum-aluminum spot welding.

[0113] The contents not described in detail in this specification belong to the prior art known to professional and technical personnel in this field.

Claims

1. A system for determining welding parameters for mixed-line cross production of steel-steel and aluminum-aluminum resistance spot welding, characterized in that: It includes a first welding parameter acquisition module and a second welding parameter determination module; The first welding parameter acquisition module is used to acquire the welding current of aluminum-aluminum resistance spot welding when an aluminum spot welding gun electrode head is used, or the welding current of steel-steel resistance spot welding when a steel spot welding gun electrode head is used from the historical production database; The second welding parameter determination module corrects the welding current of aluminum-aluminum resistance spot welding when using an aluminum spot welding gun electrode head, and determines the corrected data as the welding current of aluminum-aluminum resistance spot welding when using a steel spot welding gun electrode head, or corrects the welding current of steel-steel resistance spot welding when using a steel spot welding gun electrode head, and determines the corrected data as the welding current of steel-steel resistance spot welding when using an aluminum spot welding gun electrode head.

2. The steel-steel and aluminum-aluminum resistance spot welding mixed-line cross production welding parameter determination system according to claim 1 is characterized by: The welding current of steel-steel resistance spot welding when using a steel spot welding gun electrode head is corrected using the correction coefficient and the fluctuation range of the welding current, and the corrected data is determined as the welding current of steel-steel resistance spot welding when using an aluminum spot welding gun electrode head.

3. The steel-steel and aluminum-aluminum resistance spot welding mixed-line cross production welding parameter determination system according to claim 2 is characterized by: The calculation formula for correcting the welding current of steel-steel resistance spot welding when using the steel spot welding gun electrode tip is as follows: I2=A×I1+B (1) Wherein, I2 is the welding current of steel-steel resistance spot welding when using aluminum spot welding gun electrode head, A is the correction coefficient, I1 is the welding current of steel-steel resistance spot welding when using steel spot welding gun electrode head, and B is the fluctuation range of welding current obtained based on welding specimen test.

4. The steel-steel and aluminum-aluminum resistance spot welding mixed-line cross production welding parameter determination system according to claim 3 is characterized by: The correction factor is calculated based on the ratio of heat loss of resistance spot welding to different welding gun electrode heads and the ratio of heat loss of resistance spot welding to cooling water flow when using different welding guns. The calculation formula is as follows: In the formula, A is the correction coefficient, k1 is the ratio of heat loss of resistance spot welding caused by different welding gun electrode heads, and k2 is the ratio of heat loss of resistance spot welding caused by different welding gun cooling water flow rates.

5. The steel-steel and aluminum-aluminum resistance spot welding mixed-line cross production welding parameter determination system according to claim 4 is characterized in that: The heat loss ratio of different welding gun electrode heads to resistance spot welding is calculated according to the contact area between the aluminum spot welding gun electrode head and the steel spot welding gun electrode head and the plate to be tested under a fixed pressure, and the calculation formula is as follows: k1=S1 / S2 (3) Where, k1 is the ratio of heat loss of different welding gun electrode heads to resistance spot welding, S1 is the contact area corresponding to the aluminum spot welding gun electrode head, and S2 is the contact area corresponding to the steel spot welding gun electrode head; According to the inner surface temperature of the electrode rod under the water flow rate when using a steel spot welding gun and the water flow rate when using an aluminum spot welding gun, the proportion of the cooling water flow rate of different welding guns to the heat loss of resistance spot welding is calculated. The calculation formula is as follows: k2=(T2-298) / (T1-298) (4) Where k2 is the ratio of the cooling water flow rate of different welding guns to the heat loss of resistance spot welding, T1 is the inner surface temperature of the electrode rod under the water flow rate when using a steel spot welding gun, and T2 is the inner surface temperature of the electrode rod under the water flow rate when using an aluminum spot welding gun.

6. A method for determining welding parameters for mixed-line cross production of steel-steel and aluminum-aluminum resistance spot welding, characterized in that: It includes the following: Obtaining from the historical production database the welding current of aluminum-aluminum resistance spot welding when an aluminum spot welding gun electrode tip is used, or the welding current of steel-steel resistance spot welding when a steel spot welding gun electrode tip is used; The welding current of aluminum-aluminum resistance spot welding when using an aluminum spot welding gun electrode head is corrected, and the corrected data is determined as the welding current of aluminum-aluminum resistance spot welding when using a steel spot welding gun electrode head, or the welding current of steel-steel resistance spot welding when using a steel spot welding gun electrode head is corrected, and the corrected data is determined as the welding current of steel-steel resistance spot welding when using an aluminum spot welding gun electrode head.

7. A steel-steel and aluminum-aluminum resistance spot welding mixed line cross production system, characterized by: It comprises a welding cycle judgment module, a first welding parameter acquisition module as claimed in any one of claims 1 to 5, and a second welding parameter determination module; The welding cycle judgment module uses the aluminum spot welding gun electrode head to perform steel-steel spot welding under the determined welding current of steel-steel resistance spot welding when the aluminum spot welding gun electrode head is used, and uses the aluminum spot welding gun electrode head to perform aluminum-aluminum spot welding under the acquired welding current of aluminum-aluminum resistance spot welding when the aluminum spot welding gun electrode head is used; or using the steel spot welding gun electrode tip to perform aluminum-aluminum spot welding at the determined welding current of aluminum-aluminum resistance spot welding when using the steel spot welding gun electrode tip, and using the steel spot welding gun electrode tip to perform steel-steel spot welding at the obtained welding current of steel-steel resistance spot welding when using the steel spot welding gun electrode tip; When the number of welds of aluminum-aluminum spot welding and the number of welds of steel-steel spot welding reach the preset conditions, the next cycle of aluminum-aluminum spot welding and steel-steel spot welding is carried out; otherwise, the electrode tip of the aluminum spot welding gun is ground before continuing the next cycle of aluminum-aluminum spot welding and steel-steel spot welding.

8. The steel-steel and aluminum-aluminum resistance spot welding mixed-line cross production system according to claim 7 is characterized in that: When the number of welds of aluminum-aluminum spot welding and the number of welds of steel-steel spot welding reach the preset conditions, the calculation formulas for the next cycle of aluminum-aluminum spot welding and steel-steel spot welding are as follows: In the formula, m i is the number of welding points of the i-th aluminum-aluminum spot welding, n i is the number of welds in the i-th steel-steel spot welding, l is the total number of cycles, K is the number of welds of aluminum obtained by the mixed line cycle production of steel-steel and aluminum-aluminum resistance spot welding, and Q is the number of welds of steel obtained by steel-steel resistance spot welding.

9. The steel-steel and aluminum-aluminum resistance spot welding mixed-line cross production system according to claim 8, characterized in that: The value of K is determined as follows: using the aluminum spot welding gun electrode head to perform steel-steel and aluminum-aluminum resistance spot welding cycle production until the welds of the steel-steel resistance spot welding do not meet the steel spot welding conditions or the welds of the aluminum-aluminum resistance spot welding do not meet the aluminum spot welding conditions, and the cycle is stopped, and the total number of aluminum welds that meet the aluminum spot welding conditions during the cycle production process is counted as K; The method for obtaining the value of Q is: using the aluminum spot welding gun electrode head to perform steel-steel resistance spot welding production until the welds of the steel-steel resistance spot welding do not meet the steel spot welding conditions, and the total number of steel welds that meet the steel spot welding conditions during the production process is counted as Q.

10. A steel-steel, aluminum-aluminum resistance spot welding mixed line cross production method, characterized in that: It includes the following: Obtaining from the historical production database the welding current of aluminum-aluminum resistance spot welding when an aluminum spot welding gun electrode tip is used, or the welding current of steel-steel resistance spot welding when a steel spot welding gun electrode tip is used; Correcting the welding current of aluminum-aluminum resistance spot welding when an aluminum spot welding gun electrode tip is used, and determining the corrected data as the welding current of aluminum-aluminum resistance spot welding when a steel spot welding gun electrode tip is used, or correcting the welding current of steel-steel resistance spot welding when a steel spot welding gun electrode tip is used, and determining the corrected data as the welding current of steel-steel resistance spot welding when an aluminum spot welding gun electrode tip is used; Using the aluminum spot welding gun electrode tip to perform steel-steel spot welding at the determined welding current of steel-steel resistance spot welding when using the aluminum spot welding gun electrode tip, and using the aluminum spot welding gun electrode tip to perform aluminum-aluminum spot welding at the acquired welding current of aluminum-aluminum resistance spot welding when using the aluminum spot welding gun electrode tip; or using the steel spot welding gun electrode tip to perform aluminum-aluminum spot welding at the determined welding current of aluminum-aluminum resistance spot welding when using the steel spot welding gun electrode tip, and using the steel spot welding gun electrode tip to perform steel-steel spot welding at the obtained welding current of steel-steel resistance spot welding when using the steel spot welding gun electrode tip; When the number of welds of aluminum-aluminum spot welding and the number of welds of steel-steel spot welding reach the preset conditions, the next cycle of aluminum-aluminum spot welding and steel-steel spot welding is carried out; otherwise, the electrode tip of the aluminum spot welding gun is ground before continuing the next cycle of aluminum-aluminum spot welding and steel-steel spot welding.

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