System and method for improving resistance spot welding of cast aluminum

Abstract

A method of connecting metal substrates includes providing a first electrode and a second electrode, where at least one characteristic of the first electrode is different from that of the second electrode. The method includes applying a pressing force to at least two stacked metal substrates using the first electrode and the second electrode. Optionally, one of the at least two metal substrates may be cast aluminum. The method includes applying a current during a first time period by ramping up the current at a ramping-up rate; applying a current at a weld level during a second period of time after the first period of time; and ramp-down the current at a ramp-down rate during a third time period after the second time period. The oblique descending rate is smaller than the oblique ascending rate.

Description

[0001] Citation to Related Applications

[0002] This application claims the benefit of U.S. Provisional Patent Application No. 63 / 367,409, filed on June 30, 2022, entitled “SYSTEMS AND METHODS FOR IMPROVED RESISTANCE SPOT WELDING OF CAST ALUMINUM,” the contents of which are incorporated herein by reference in their entirety. Technical Field

[0003] The present application relates to resistance spot welding and, more particularly, to control systems and methods for improving aluminum resistance spot welding. Background Art

[0004] Metal manufacturing can include welding a metal substrate or a metal alloy substrate together to form various parts or components of a final product. Various techniques or processes, including, for example, resistance spot welding, can be used to weld metal substrates. Resistance spot welding can include placing a metal substrate between electrodes and using electrodes to apply a pressing force and an electric current to the metal substrate. The heat generated by the resistance of the metal substrate to the electric current, together with the pressing force of the electrodes, can be used to connect the metal substrates at the interface, thereby forming a local cohesive zone known as a spot welding nugget. However, some metals may be difficult to weld with conventional welding techniques, and may be difficult to weld two different types of metal substrates together. For example, the conventional resistance spot welding of cast aluminum to aluminum plate may have internal cracks (causing strength and fatigue problems), limited penetration of the aluminum plate (causing strength problems), welding spatter, and poor end life of the electrode, among other problems. Summary of the invention

[0005] The terms "invention," "said invention," "the invention," and "present invention" as used in this patent are intended to refer broadly to all subject matter of this patent and the patent claims below. Statements containing these terms should be understood not to limit the subject matter described herein or to limit the meaning or scope of the patent claims below. The embodiments of the described invention covered by this patent are defined by the claims below rather than by this summary of the invention. This summary of the invention is a high-level overview of various embodiments of the described invention and introduces some of the concepts that are further described in the detailed description section below. This summary of the invention is not intended to indicate key or essential features of the claimed subject matter, nor is it intended to be used alone to determine the scope of the claimed subject matter. The subject matter should be understood by reference to appropriate portions of the entire specification of this patent, any or all of the drawings, and each claim.

[0006] According to certain embodiments, a method for connecting metal substrates includes providing a first electrode and a second electrode, wherein at least one feature of the first electrode is different from that of the second electrode. The method includes applying a pressing force to at least two superimposed metal substrates using the first electrode and the second electrode. In certain embodiments, at least one of the at least two metal substrates includes aluminum or an aluminum alloy. The method includes, during a first time period, applying a current at a first level and ramping the current from the first level to a second level greater than the first level, and after the first time period, applying a current at a second level for a second time period. In various embodiments, the method includes, after the second time period, ramping down the current from the second level during a third time period. The rate at which the current ramps down is less than the rate at which the current ramps up during the first time period.

[0007] According to some embodiments, a method for connecting metal substrates includes providing a first electrode and a second electrode, wherein at least one feature of the first electrode is different from that of the second electrode. The method includes applying a pressing force to at least two stacked metal substrates using the first electrode and the second electrode. In some embodiments, at least one of the at least two metal substrates includes aluminum or an aluminum alloy. The method includes: during a first time period, applying a current at a first level and ramping the current from the first level to a second level greater than the first level. The method also includes: after the first time period, applying a current at a third level for a second time period, and after the second time period, ramping down the current from the third level during the third time period.

[0008] According to various embodiments, a method for connecting metal substrates includes providing a first electrode and a second electrode, wherein at least one feature of the first electrode is different from that of the second electrode. The method includes applying a compressive force to at least two stacked metal substrates using the first electrode and the second electrode. In some embodiments, at least one of the at least two metal substrates includes aluminum or an aluminum alloy. The method includes applying a current by: ramping up the current at a ramp-up rate during a first time period; applying the current at a welding level during a second time period after the first time period; and ramping down the current at a ramp-down rate during a third time period after the second time period. In some embodiments, the ramp-down rate is less than the ramp-up rate.

[0009] Improved welds can be formed by the methods described herein.In some embodiments, a weld is formed in at least two metal substrates, wherein a first metal substrate of the at least two metal substrates is an aluminum sheet and a second metal substrate of the at least two metal substrates is cast aluminum.

[0010] The various embodiments described in the present disclosure may include additional systems, methods, features and advantages that are not necessarily explicitly disclosed herein, but will be apparent to one of ordinary skill in the art upon review of the following detailed description and accompanying drawings. It is contemplated that all such systems, methods, features and advantages are included in the present disclosure and protected by the appended claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The features and components in the following figures are illustrated to emphasize the general principles of the present disclosure. For consistency and clarity, corresponding features and components throughout the various figures may be designated by matching reference characters.

[0012] Figure 1 A resistance spot welding system according to an embodiment is illustrated.

[0013] Figure 2 Picture shows Figure 1 Electrodes for resistance spot welding systems.

[0014] Figure 3A A portion of a punching tool according to an embodiment is illustrated.

[0015] Figure 3B Illustration of the use Figure 3A Stamping tools for stamping Figure 1 Electrodes for resistance spot welding systems.

[0016] Figure 4A A portion of a punching tool according to an embodiment is illustrated.

[0017] Figure 4B Illustration of the use Figure 4A Stamping tools for stamping Figure 1 Electrodes for resistance spot welding systems.

[0018] Figure 5 A resistance spot welding system according to an embodiment is illustrated.

[0019] Figure 6 is a diagram depicting a welding profile plan according to an embodiment.

[0020] Figure 7 is a diagram depicting another welding profile plan according to an embodiment.

[0021] Figure 8 A method of connecting metal substrates according to an embodiment is illustrated.

[0022] Fig. 9 A weld formed by resistance spot welding according to an embodiment is illustrated.

[0023] Fig.10A weld formed by resistance spot welding according to an embodiment is illustrated.

[0024] Fig.11 A weld formed by resistance spot welding according to an embodiment is illustrated. DETAILED DESCRIPTION

[0025] Described herein are methods and systems for joining two or more metal substrates together by resistance spot welding. According to the systems and methods described herein, during a welding technique, a compressive force and an electric current may be applied to the metal substrate by at least two electrodes. In certain embodiments, at least one feature of a first electrode of the at least two electrodes may be different from at least one feature of a second electrode of the at least two electrodes. In certain embodiments, the at least one feature may include, but is not limited to, a topography of an electrode tip and / or a tip radius of an electrode tip.

[0026] Applying a clamping force and an electric current may include controlling an amount of electric current according to a welding curve provided herein while applying a certain amount of clamping force to the metal substrate. Controlling the amount of electric current according to the welding curve described herein together with an asymmetric electrode can reduce spatter during current ramp-up and reduce crack sensitivity during current ramp-down.

[0027] When one or both metal substrates are aluminum or aluminum alloys, the systems and methods provided herein may be useful. The systems and methods described herein may be particularly useful for connecting cast aluminum to aluminum plates. As a non-limiting example, the systems and methods described herein may produce welds in metal substrates, which include cast aluminum connected to aluminum plates, and their penetration in the aluminum plates is improved. In some non-limiting examples, the welds formed according to the methods described herein may be approximately centered between cast aluminum and aluminum plates. In a non-limiting example, the welds formed according to the methods and systems described herein may penetrate more than about 10% of the thickness of the aluminum plate, such as about 20% of the thickness of the aluminum plate, such as about 30% of the thickness of the aluminum plate, such as about 40% of the thickness of the aluminum plate, such as about 50% of the thickness of the aluminum plate, or more. Optionally, the penetration may be less than about 100% of the thickness of the aluminum plate, such as optionally less than about 90% of the thickness of the aluminum plate. In various embodiments, at least one metal substrate may be cast aluminum or a cast aluminum alloy. Various other benefits and advantages may be achieved by the systems and methods provided herein, and the advantages described above should not be considered limiting.

[0028] Figure 1The system 100 for resistance spot welding at least the first metal substrate 102 and at least the second metal substrate 104 is illustrated. In certain embodiments, the system 100 can be used to connect a plurality of metal substrates. In some examples, one or more of the metal substrates can be aluminum or an aluminum alloy. In some cases, the aluminum or aluminum alloy in the 1xxx series, 2xxx series, 3xxx series, 4xxx series, 5xxx series, 6xxx series, 7xxx series, 8xxx series and / or any other aluminum or aluminum alloy material can be utilized as one or more of the metal substrates.

[0029] By way of non-limiting example, exemplary 1xxx alloys for use with the methods and products described herein may include AA1100, AA1100A, AA1200, AA1200A, AA1300, AA1110, AA1120, AA1230, AA1230A, AA1235, AA1435, AA1145, AA1345, AA1445, AA1150, AA1350, AA1350A, AA1450, AA1370, AA1275, AA1185, AA1285, AA1385, AA1188, AA1190, AA1290, AA1193, AA1198, or AA1199.

[0030] Non-limiting exemplary 2xxx series alloys for use in the methods and products described herein may include AA2001, AA2002, AA2004, AA2005, AA2006, AA2007, AA2007A, AA2007B, AA2008, AA2009, AA2010, AA2011, AA2011A, AA2111, AA2111A, AA2111B, AA2012, AA2013, AA2014, AA2015, AA2016, AA2017, AA2018, AA2019, AA2020, AA2021 2014A, AA2214, AA2015, AA2016, AA2017, AA2017A, AA2117, AA2018, AA2218, AA2618, AA2618A, AA2219, A A2319, AA2419, AA2519, AA2021, AA2022, AA2023, AA2024, AA2024A, AA2124, AA2224, AA2224A, AA2324, A A2424, AA2524, AA2624, AA2724, AA2824, AA2025, AA2026, AA2027, AA2028, AA2028A, AA2028B, AA2028C, AA2029, AA2030, AA2031, AA2032, AA2034, AA2036, AA2037, AA2038, AA2039, AA2139, AA2040, AA2041, AA 2044, AA2045, AA2050, AA2055, AA2056, AA2060, AA2065, AA2070, AA2076, AA2090, AA2091, AA2094, AA20 95, AA2195, AA2295, AA2196, AA2296, AA2097, AA2197, AA2297, AA2397, AA2098, AA2198, AA2099 or AA2199.

[0031] Non-limiting exemplary 3xxx series alloys for use in the methods and products described herein may include AA3002, AA3102, AA3003, AA3103, AA3103A, AA3103B, AA3203, AA3403, AA3004, AA3004A, AA3104, AA3204, AA3304, AA3005, AA3005A, AA3105, AA3105A, AA3105B, AA3203, AA3403, AA3004, AA3004A, AA3104, AA3204, AA3304, AA3005 AA3007, AA3107, AA3207, AA3207A, AA3307, AA3009, AA3010, AA3110, AA3011, AA3012, AA3012A, AA3013, AA3014, AA3015, AA3016, AA3017, AA3019, AA3020, AA3021, AA3025, AA3026, AA3030, AA3130, or AA3065.

[0032] Non-limiting exemplary 4xxx series alloys for use with the methods and products described herein may include AA4004, AA4104, AA4006, AA4007, AA4008, AA4009, AA4010, AA4013, AA4014, AA4015, AA4015A, AA4115, AA4016, AA4017, AA4018, AA4019, AA4020, AA4021, AA4026, AA4032, AA4043, AA4043A, AA4143, AA4343, AA4643, AA4943, AA4044, AA4045, AA4145, AA4145A, AA4046, AA4047, AA4047A, or AA4147.

[0033] Non-limiting exemplary 5xxx series alloys for use in the methods and products described herein may include AA5182, AA5183, AA5005, AA5005A, AA5205, AA5305, AA5505, AA5605, AA5006, AA5106, AA5010, AA5110, AA5110A, AA5210, AA5310, AA5016, AA5017, AA5018, AA5018A, AA5019, AA5019A, AA5119 ... A5119A, AA5021, AA5022, AA5023, AA5024, AA5026, AA5027, AA5028, AA5040, AA5140, AA5041, AA5042, AA5043, AA504 9. AA5149, AA5249, AA5349, AA5449, AA5449A, AA5050, AA5050A, AA5050C, AA5150, AA5051, AA5051A, AA5151, AA5251, AA5251A, AA5351, AA5451, AA5052, AA5252, AA5352, AA5154, AA5154A, AA5154B, AA5154C, AA5254, AA5354, AA5454, A A5554, AA5654, AA5654A, AA5754, AA5854, AA5954, AA5056, AA5356, AA5356A, AA5456, AA5456A, AA5456B, AA5556, AA5 556A, AA5556B, AA5556C, AA5257, AA5457, AA5557, AA5657, AA5058, AA5059, AA5070, AA5180, AA5180A, AA5082, AA51 82. AA5083, AA5183, AA5183A, AA5283, AA5283A, AA5283B, AA5383, AA5483, AA5086, AA5186, AA5087, AA5187 or AA5088.

[0034] Non-limiting exemplary 6xxx series alloys for use in the methods and products described herein may include AA6101, AA6101A, AA6101B, AA6201, AA6201A, AA6401, AA6501, AA6002, AA6003, AA6103, AA6005, AA6005A, AA6005B, AA6005C, AA6105, AA6205, AA6305, AA6006, AA6106, AA6206, AA6306 ... A6008, AA6009, AA6010, AA6110, AA6110A, AA6011, AA6111, AA6012, AA6012A, AA6013, AA6113, AA6014, AA6015, AA 6016, AA6016A, AA6116, AA6018, AA6019, AA6020, AA6021, AA6022, AA6023, AA6024, AA6025, AA6026, AA6027, AA60 28. AA6031, AA6032, AA6033, AA6040, AA6041, AA6042, AA6043, AA6151, AA6351, AA6351A, AA6451, AA6951, AA605 3. AA6055, AA6056, AA6156, AA6060, AA6160, AA6260, AA6360, AA6460, AA6460B, AA6560, AA6660, AA6061, AA6061A , AA6261, AA6361, AA6162, AA6262, AA6262A, AA6063, AA6063A, AA6463, AA6463A, AA6763, A6963, AA6064, AA6064A, AA6065, AA6066, AA6068, AA6069, AA6070, AA6081, AA6181, AA6181A, AA6082, AA6082A, AA6182, AA6091, or AA6092.

[0035] Non-limiting exemplary 7xxx series alloys for use in the methods and products described herein may include AA7011, AA7019, AA7020, AA7021, AA7039, AA7072, AA7075, AA7085, AA7108, AA7108A, AA7015, AA7017, AA7018, AA7019A, AA7024, AA7025, AA7028 ,AA7030,AA7031,AA7033,AA7035,AA7035A,AA7046,AA7046A,AA7003,AA7004,AA7005,AA7 009, AA7010, AA7011, AA7012, AA7014, AA7016, AA7116, AA7122, AA7023, AA7026, AA7029, AA7 129, AA7229, AA7032, AA7033, AA7034, AA7036, AA7136, AA7037, AA7040, AA7140, AA7041, AA 7049, AA7049A, AA7149, 7204, AA7249, AA7349, AA7449, AA7050, AA7050A, AA7150, AA7250, AA AA7055, AA7055, AA7155, AA7255, AA7056, AA7060, AA7064, AA7065, AA7068, AA7168, AA7175, AA7475, AA7076, AA7178, AA7278, AA7278A, AA7081, AA7181, AA7185, AA7090, AA7093, AA7095, or AA7099.

[0036] Non-limiting exemplary 8xxx series alloys for use in the methods and products described herein may include AA8005, AA8006, AA8007, AA8008, AA8010, AA8011, AA8011A, AA8111, AA8211, AA8112, AA8014, AA8015, AA8016, AA8017, AA8018, AA8019, AA8020, AA8021A, AA8022, AA8023, AA8024, AA8025, AA8026, AA8027, AA8028, AA8029, AA8030, AA8031, AA8032, AA8033, AA8034, AA8035, AA8036, AA8037, AA8038, AA8039, AA8040, AA8041, AA8042, AA8043, AA8044, AA8045, AA8046, AA8047, AA8048, AA8049, AA8050, AA8051 1. AA8021A, AA8021B, AA8022, AA8023, AA8024, AA8025, AA8026, AA8030, AA8130, AA8040, AA8050, AA8150, AA8076, AA8076A, AA8176, AA8077, AA8177, AA8079, AA8090, AA8091, or AA8093.

[0037] The composition of one metal substrate (e.g., the first metal substrate 102) need not be the same as the composition of another metal substrate (e.g., the second metal substrate 104), although it can be the same. Each metal substrate 102, 104 can have various sizes or thicknesses as needed, and the size or thickness of one metal substrate need not be the same as the size or thickness of another metal substrate (although it can be the same). Figure 1 As illustrated, the metal substrates 102 , 104 may be arranged relative to one another such that the metal substrates 102 , 104 are stacked and have outermost opposing sides or surfaces 110 , 112 .

[0038] In one non-limiting example, one or more of the metal substrates (e.g., the second metal substrate 104) can be cast aluminum formed by a casting method, such as a casting technique such as die casting, mold casting, or sand casting, and the other metal substrate (e.g., the first metal substrate 102) can be an aluminum plate. The surface of the cast aluminum can have various surface treatments and / or qualities as needed. As a non-limiting example, the surface of the cast aluminum can be provided in the cast state, acid etched, mechanically brushed, laser cleaned, and / or otherwise as needed. For the purpose of discussion, the first metal substrate 102 will be referred to as a plate-like substrate 102, and the second metal substrate 104 will be referred to as a cast substrate 104; however, in other embodiments, the arrangement of the cast substrate 104 and the plate-like substrate 102 can be reversed and / or arranged in other ways as needed.

[0039] The resistance spot welding system 100 includes electrodes 106A-B. Although two electrodes 106A-B are illustrated, any number of electrodes may be used with the system 100 as desired. The electrodes 106A-B may be any suitable type of electrode for providing the desired conductivity during welding, and may include, but are not limited to, copper electrodes, steel electrodes, and / or tungsten electrodes. For purposes of discussion, the electrode 106A will be referred to as the plate-side electrode 106A for contacting the plate-like substrate 102, and the electrode 106B will be referred to as the casting-side electrode 106B for contacting the casting substrate 104; however, as previously described, the electrodes 106A-B may be provided in various arrangements as desired.

[0040] In some embodiments, the electrodes 106A-B are communicatively coupled to a welding controller 114, which is used to control one or more welding parameters during resistance spot welding, including but not limited to welding duration and welding current. In one non-limiting example, the welding controller 114 can be a medium frequency DC controller, although in other embodiments, the welding controller 114 can be various other suitable devices or mechanisms as needed. In various aspects, the welding controller 114 can control one or more welding parameters based on the characteristics of the metal substrates 102, 104 to be connected and / or other characteristics of the resistance spot welding system 100. For example, the welding controller 114 can control the welding duration and / or welding current based at least in part on the composition of the metal substrates 102, 104, the thickness or size of the metal substrates 102, 104, the size of the electrodes 106A-B, the characteristics of the electrodes 106A-B, and / or other characteristics as needed. In some embodiments, the welding controller 114 controls the resistance spot welding system 100 according to the welding curve plan 600 and / or the welding curve plan 700, as described in detail below. As discussed in detail below, the welding current provided for the welding duration and in accordance with the welding profile plan 600 and / or the welding profile plan 700 produces a spot weld nugget 108 having a minimum weld size for joining the metal substrates 102, 104, or a spot weld nugget that meets the dimensional and mechanical requirements of the joint. The minimum weld size is defined as Where t is the thickness of the ruling metal thickness. In a stack of two metal substrates, the ruling metal thickness is usually the thinnest substrate.

[0041] In various embodiments, at least one feature of the plate side electrode 106A is different from the cast side electrode 106B, and the electrodes 106A-B may be considered asymmetric, where the different feature of one of the electrodes 106A-B is a weld positioning feature. The asymmetric electrode may provide improved control of current flow direction and / or local current density during a welding cycle, which may improve the formation and positioning of the spot weld nugget 108 at the interface of the metal substrates 102, 104. In embodiments where the metal substrates 102, 104 include a cast substrate 104 and a plate substrate 102, the asymmetric electrodes 106A-B may improve the penetration of the spot weld nugget 108 in the aluminum plate, optionally forming a spot weld nugget 108 approximately centered between the cast aluminum and the aluminum plate. The at least one feature may be other features of the electrodes 106A-B suitable for controlling current flow direction and / or local current density during a welding cycle as desired.

[0042] exist Figure 1 In the illustrated embodiment, at least one feature of the electrodes is the surface topography of the tip 116 of each electrode 106A-B—the plate-side electrode 106A is stamped with the surface features 124 on the tip 116, and the casting-side electrode 106B is not stamped. Figure 2 In some embodiments, a stamping tool 218 having a textured surface 220 may be used to stamp or otherwise impart topography to the plate-side electrode 106A. The textured surface 220 may have a variety of patterns, shapes, etc. as desired and is suitable for controlling the application of current during a welding cycle. Figure 3A A non-limiting example of a stamping tool 318 is shown having pyramidal ribs 322 that form a textured surface 320. The stamping tool 318 may form a corresponding pyramidal recess 324 on the end 316 of the electrode 306, such as Figure 3B As shown. Figure 4A A non-limiting example of a stamping tool 418 is shown having ribs 422 that form a textured surface 420 and are elongated compared to ribs 322. Figure 4B As shown, the electrode 406 punched with the punch tool 418 can be formed with a corresponding elongated recess 424 on its tip 416. As mentioned, in embodiments having a cast substrate 104 and a plate-like substrate 102, the plate-side electrode 106A having a textured tip 116 can be arranged to contact the plate-like substrate 102, which can facilitate centering and / or penetration of the weld within the aluminum plate. Various other textures and / or patterns of textures can be used as desired. In some embodiments, when the plate-side electrode 106A includes a textured / stamped tip, the other electrode 106B can be unstamped / untextured, or can have a different texture than the plate-side electrode 106A.

[0043] As another non-limiting example, Figure 5 The resistance spot welding system 500 is illustrated, which is substantially similar to the resistance spot welding system 100, except that the plate side electrode 506A and the casting side electrode 506B have a tip 516 with a different tip radius. The electrodes 506A-B can have various tip radii as needed. In a non-limiting example, the tip radius of the plate side electrode 506A can be about half of the tip radius of the casting side electrode 506B, although it does not have to be so in other embodiments. As a non-limiting example, the plate side electrode 506A can have a tip radius less than or equal to about 100 mm, such as about 75 mm. In some embodiments, the plate side electrode 506A can have a tip radius from about 25 mm to about 75 mm. As another non-limiting example, the casting side electrode 506B can have a tip radius greater than or equal to about 100 mm, such as about 150 mm. In some embodiments, the casting side electrode 506B can have a tip radius from about 100 mm to about 150 mm.

[0044] In other non-limiting examples, the tip radius of one electrode may be from about 100 mm to about 150 mm, inclusive, and the tip radius of the other electrode may be from about 20 mm to about 75 mm, inclusive. In a non-limiting embodiment where one of the metal substrates 102, 104 is cast aluminum and the other is an aluminum plate, the electrode with a smaller tip radius (e.g., the plate side electrode 506A having a tip radius from about 20 mm to about 75 mm) may be arranged to contact the aluminum plate, and the electrode with a larger tip radius (e.g., the cast side electrode 506B having a tip radius from about 100 mm to about 150 mm) may be arranged to contact the cast aluminum, which may facilitate centering and / or penetration of the weld within the aluminum plate.

[0045] In another non-limiting example, each electrode 106A-B has a diameter, and the diameters of the electrodes 106A-B can be the same, although this need not be the case in other embodiments. As a non-limiting example, the diameter of each end can be from about 12 mm to about 20 mm, such as about 12 mm, about 13 mm, about 14 mm, about 15 mm, about 16 mm, about 17 mm, about 18 mm, about 19 mm, and / or about 20 mm.

[0046] In some embodiments, in addition to changing one or more adjustments of the electrodes 106A-B, the characteristics of the surfaces 110, 112 can optionally be controlled and optionally changed to be asymmetric. As non-limiting examples, the surface 112 of the casting substrate 104 can be an as-cast surface (e.g., no pre-treatment), an acid-etched surface, an acid-etched and TiZr pre-treated surface, a laser-cleaned surface (e.g., a Gaussian laser-cleaned surface, a continuous wave laser-cleaned surface, etc.), combinations thereof, and / or have other desired surface characteristics.

[0047] Optionally, an adhesive may be provided between the plate substrate 102 and the casting substrate 104. In other embodiments, the adhesive may be omitted.

[0048] In some embodiments, multiple features can be different between one electrode and another electrode (and optionally between surfaces 110, 112). As an example, one electrode (e.g., the plate side electrode 106A) can be stamped and have a reduced end radius, and the other electrode (e.g., the casting side electrode 106B) can be unstamped and have a larger end radius, or the stamped electrode can have a larger end radius and the unstamped electrode can have a reduced end radius. As another example, one electrode can be stamped with a first morphology and a first end radius, and the other electrode can be stamped with a second morphology and a second end radius. As another example, two electrodes can have the same end radius, and one electrode is stamped and the other electrode is unstamped. Various other combinations of morphologies, radii, and / or other features or combinations of features can be utilized as desired.

[0049] Figure 6 A welding profile plan 600 is illustrated according to various embodiments. The welding profile plan 600 includes both a compaction force 602 and an electrical current 604 applied to the metal substrates 102, 104 to form a weld such as a spot weld nugget 108. In certain embodiments, the welding profile plan 600 can improve the positioning and / or formation of the spot weld nugget 108, particularly when one of the metal substrates 102, 104 is an aluminum plate and the other is cast aluminum. The welding profile plan 600 will be discussed in conjunction with the resistance spot welding system 100, in which the electrodes 106A-B are asymmetrical due to the topography printed on the plate side electrode 106A. However, the welding profile plan 600 can be used for any welding or system consistent with the embodiments described herein.

[0050] like Figure 6 As depicted, a compressive force 602 and an electric current 604 are applied to two or more metal substrates 102, 104 through electrodes 106A-B. In various embodiments, and as previously discussed, the metal substrates 102, 104 may be metal alloys, and optionally, one of the metal substrates (e.g., metal substrate 102) is an aluminum plate, and the other of the metal substrates (e.g., metal substrate 104) is cast aluminum. In certain embodiments, the metal substrates 102, 104 are arranged such that the plate-like substrate 102 will be welded with a weld positioning feature (e.g., Figure 1 Surface features in 124, Figure 5 The plate side electrode 106A (a reduced end radius, etc.) contacts and presses.

[0051] In some embodiments, the clamping force 602 is applied before the current 604 is applied and maintained during the current 604. In some embodiments, a constant clamping force 602 is applied during the duration of the current 604. In various embodiments, the constant clamping force 602 can reduce potential welding fluctuations. Various clamping forces 602 can be applied as needed. As a non-limiting example, the clamping force can be from greater than 0kN to about 10kN, such as from about 4kN to about 8kN, such as from about 5kN to about 7kN, such as about 6kN and / or such as about 6.5kN. In other embodiments, the clamping force 602 can be other clamping forces as needed. The clamping force 602 can be applied during a force duration with a force start time 606 and a force end time 608. The time period between the force start time 606 and the force end time 608 can be any time span or duration as needed.

[0052] The current 604 may correspond to various amounts of current, energy, or heat, and may be applied at various levels, as discussed in detail below. In some examples, the level of the current 604 may be between 0 kA and about 65 kA, such as from greater than 0 kA to about 55 kA, such as from greater than 0 kA to about 45 kA, such as from greater than 0 kA to about 40 kA, such as greater than 0 kA to about 35 kA. However, in other embodiments, the current 604 may be applied at different levels as desired.

[0053] The current 604 can be controlled and selectively applied for a current duration having a current start time 610 and a current end time 612. In some embodiments, the current duration is less than the force duration. In various aspects, the current start time 610 is a predetermined duration or time period after the force start time 606. In such an example, delaying the current start time 610 to after the force start time 206 can ensure that the metal substrate is positioned between the electrodes 106A-B as desired.

[0054] As mentioned, the current 604 may be applied at various levels and for certain time periods during the current duration. In some embodiments, during a first time period 614 (or "ramp-up" time period), the current 604 ramps from a first level 616 to a second level 618 that is greater than the first level 616. In some embodiments, the first level 616 may be 0 kA (e.g., the current ramps from 0 kA to the welding current used during the second time period 620), although in other embodiments it need not be. In some aspects, applying the current 604 ramped from the first level 616 of the first time period 614 to the second level may avoid or minimize potential explosions, among other benefits.

[0055] After the first time period 614 and during the second time period 620, the current 604 is applied at a second level 618. In some embodiments, applying the current 604 at the second level 618 during the second time period 620 may allow for the creation of a spot weld nugget. In some embodiments, the second time period 620 may optionally be less than the first time period 614, although in other examples it need not be.

[0056] After the second time period 620, the current 604 is ramped down (e.g., reduced) from the second level 618 during a third time period 622 (or "ramp-down" time period). In some embodiments, the ramp-down rate at which the current 604 is ramped down during the third time period 622 can be less than the ramp-up rate during the first time period 614. The third time period 622 can be longer than the first time period 614. In some embodiments, the longer duration and / or reduced rate of change of the ramp-down rate compared to the first time period 614 can reduce crack sensitivity (e.g., reduce the tendency of cracks or other defects to form in the solidified spot weld nugget), among other benefits, thereby improving the quality of the weld. In some embodiments, during the third time period 622, the current 604 is ramped down from the second level 618 to the third level 624. In some embodiments, the third level 624 can be 0 kA (e.g., the current is ramped down from the second level 618 to 0 kA), although in other embodiments it need not be. In some embodiments and as Figure 2 As illustrated, the third level 624 may be the same as the first level 616; however, in other embodiments, the third level 624 may be less than or greater than the first level 616 as desired.

[0057] Figure 6 The welding curve plan 600 in FIG. 6 is provided for illustration purposes only, and the specific values ​​of the level of the current 604, the level of the clamping force 602, and / or the time period of the current 604 should not be considered limiting. As a non-limiting example, Figure 7 Another example of a welding profile plan 700 according to an embodiment of the present disclosure is illustrated.

[0058] Welding profile plan 700 is similar to welding profile plan 600 and includes a clamping force 602 and a current 604. Compared to welding profile plan 600, a first time period 614 of welding profile plan 700 starts at a first intermediate level 626 that is greater than first level 616 and less than second level 618. In addition, the rate at which current 604 ramps up during first time period 614 is reduced in welding profile plan 700 compared to welding profile plan 600. Thus, in welding profile plan 700, during first time period 614, current 604 ramps up from first intermediate level 626 to second intermediate level 628 that is greater than first intermediate level 626 and less than second level 618. Similar to welding profile plan 600, welding profile plan 700 applies current 604 at second level 618 during second time period 620 and ramps down current from second level 618 during third time period 622.

[0059] In one non-limiting example, the weld profile plan 700 may be particularly useful when using the resistance spot welding system 500, where the weld locating feature is a reduced tip radius of the plate-side electrode 506A for contacting an aluminum plate (rather than cast aluminum) as the plate-like substrate 102. However, the weld profile plan 700 is not limited to the resistance spot welding system 500, and may be used with other resistance spot welding systems consistent with the present disclosure.

[0060] Figure 8 A method of connecting at least two metal substrates 102, 104 using a welding profile plan according to various embodiments is illustrated. Figure 6 The welding curve plan shown in the figure is 600 and Figure 1 The resistance spot welding system 100 is illustrated in FIG. 1 , but the method may be performed with other welding curve plans consistent with the present disclosure and / or with other systems as desired.

[0061] In block 802, the method includes applying a clamping force 602 to the metal substrates 102, 104 using electrodes 106A-B. In some embodiments, applying the clamping force brings the metal substrates 102, 104 into contact with each other and / or may position the metal substrates 102, 104 relative to each other. In some embodiments, the metal substrate 102 is an aluminum plate and the metal substrate 104 is cast aluminum, and block 402 may include positioning the metal substrates 102, 104 and / or the resistance spot welding system 100 so that the plate-side electrode 106A having a weld positioning feature (e.g., surface feature 124) will contact the aluminum plate. The method may include performing the steps illustrated in blocks 804, 806, and 808 while applying the clamping force.

[0062] In block 804, the method includes applying the current 604 during the first time period 614. In various embodiments, block 804 includes ramping the current 604 from the first level 616 to the second level 618 during the first time period 214. In other embodiments, such as the welding profile plan 700, block 804 may include ramping the current 604 from the first intermediate level 626 and / or ramping to the second intermediate level 628.

[0063] In block 806, the method includes applying the current 204 at the second level 618 for a second time period 620. In block 808, the method includes ramping down the current 604 from the second level 618 during a third time period 622.

[0064] Figure 9-11 Non-limiting examples of RSW joints formed using weld profile plan 600 or weld profile plan 700 are illustrated.

[0065] Fig. 9 The diagram shows the use of a welding curve plan 600 and having a Figure 3B The RSW joint 901 is formed with the morphology shown in FIG. In this embodiment, the metal substrate 902 is a 6xxx series aluminum alloy plate having a thickness of 2.0 mm, and the metal substrate 904 is cast aluminum having a thickness of 3.0 mm. Figure 3B The electrode of the topography is in contact with the metal substrate 902. In this embodiment, the first time period is 40 milliseconds (ms), the second time period is 80 ms, and the third time period is 200 ms. The second level of current is 38 kA. The applied pressing force is 6 kN. Fig. 9 As illustrated, the spot weld nugget 908 formed at the interface of the substrates 902, 904 penetrates approximately 0.943 mm into the aluminum plate, which is approximately 47% of the thickness of the aluminum plate.

[0066] Fig.10 The diagram shows a welding curve plan 600 and a welding curve plan 600 having a welding curve plan 600 and a welding curve plan 600 having a welding curve plan 600 and a welding curve plan 600 using ... Figure 4B The RSW joint 1001 is formed with the morphology shown in FIG. In this embodiment, the metal substrate 1002 is a 6xxx series aluminum alloy plate having a thickness of 2.0 mm, and the metal substrate 1004 is cast aluminum having a thickness of 3.0 mm. Figure 4B The electrode of the topography is in contact with the metal substrate 1002. In this embodiment, the first time period is 40ms, the second time period is 80ms, and the third time period is 200ms. The second level of current is 38kA. The applied pressing force is 6kN. Fig.10 As illustrated, the spot weld nugget 1008 formed at the interface of the substrates 1002, 1004 penetrates into the aluminum plate by approximately 0.873 mm, which is approximately 43% of the thickness of the aluminum plate.

[0067] Fig.11 The diagram shows the use of a welding curve plan 700 and having one of the electrodes having Figure 5 1. The RSW joint 1101 is formed with the morphology shown in FIG. In this embodiment, the metal substrate 1102 is a 6xxx series aluminum alloy plate having a thickness of 2.0 mm, and the metal substrate 1104 is cast aluminum having a thickness of 3.0 mm. Figure 5 The electrode with a reduced tip radius is in contact with the metal substrate 1102. In this embodiment, the first time period is 70 ms, the second time period is 80 ms, and the third time period is 200 ms. The second level of current is 32 kA. The applied pressing force is 6 kN. Fig.11 As illustrated, the total thickness of the spot weld nugget 1108 formed at the interface of the substrates 1102 , 1104 is 3.439 mm, which is approximately 69% of the thickness of the stacked substrates 1102 , 1104 .

[0068] A series of exemplary embodiments are provided below, including at least some embodiments expressly listed as "illustrative", to provide additional description of various exemplary embodiments according to the concepts described herein. These illustrations are not meant to be mutually exclusive, exhaustive, or limiting; and the present disclosure is not limited to these illustrative illustrations, but includes all possible modifications and variations within the scope of the issued claims and their equivalents.

[0069] Example 1. A method for connecting metal substrates, the method comprising: providing a first electrode and a second electrode, wherein at least one feature of the first electrode is different from that of the second electrode; applying a pressing force to at least two stacked metal substrates using the first electrode and the second electrode, wherein at least one of the at least two metal substrates comprises aluminum or an aluminum alloy; during a first time period, applying a current at a first level and ramping the current from the first level to a second level greater than the first level; after the first time period, applying the current at the second level for a second time period; and after the second time period, ramping down the current from the second level during a third time period, wherein the rate at which the current is ramped down is less than the rate at which the current is ramped up during the first time period.

[0070] Example 2. The method according to any one of the preceding or following examples or combinations of examples, wherein a first metal substrate of the at least two metal substrates comprises cast aluminum, and wherein a second metal substrate of the at least two metal substrates comprises an aluminum plate.

[0071] Example 3. A method according to any one of the preceding or following examples or combinations of examples, wherein the first time period is shorter than the third time period.

[0072] Example 4. The method according to any one of the preceding or following examples or combinations of examples, wherein the third time period is longer than the first time period and longer than the second time period.

[0073] Example 5. A method according to any one of the preceding or following examples or combinations of examples, wherein the at least one feature includes a topography of the end of the first electrode, and wherein the method includes stamping the first electrode and printing the topography on the end of the first electrode.

[0074] Example 6. A method according to any one of the preceding or following examples or combinations of examples, wherein a first metal substrate among the at least two metal substrates comprises an aluminum plate, wherein a second metal substrate among the at least two metal substrates comprises cast aluminum, and applying the clamping force comprises contacting the first electrode with the first metal substrate.

[0075] Example 7. A method according to any one of the preceding or following examples or combinations of examples, wherein the at least one feature includes a terminal radius of the terminal end of the first electrode, and wherein the terminal radius of the first electrode is smaller than the terminal radius of the second electrode.

[0076] Example 8. A method according to any one of the preceding or following examples or combinations of examples, wherein a first metal substrate among the at least two metal substrates comprises an aluminum plate, wherein a second metal substrate among the at least two metal substrates comprises cast aluminum, and applying a clamping force comprises contacting the first electrode with the first metal substrate.

[0077] Example 9. A method for connecting metal substrates, the method comprising: providing a first electrode and a second electrode, wherein at least one feature of the first electrode is different from that of the second electrode; applying a pressing force to at least two stacked metal substrates using the first electrode and the second electrode, wherein at least one of the at least two metal substrates comprises aluminum or an aluminum alloy; applying a current at a first level during a first time period and ramping the current from the first level to a second level greater than the first level; after the first time period, applying the current at a third level for a second time period; and after the second time period, ramping down the current from the third level during a third time period.

[0078] Example 10. The method according to any preceding or following example or any combination of examples, wherein the third level is greater than the second level.

[0079] Example 11. A method according to any of the preceding or following examples or combinations of examples, wherein the at least one feature includes a terminal radius of the terminal end of the first electrode, and wherein the terminal radius of the first electrode is smaller than the terminal radius of the second electrode.

[0080] Example 12. A method according to any one of the preceding or following examples or combinations of examples, wherein a first metal substrate among the at least two metal substrates comprises an aluminum plate, wherein a second metal substrate among the at least two metal substrates comprises cast aluminum, and applying a clamping force comprises contacting the first electrode with the first metal substrate.

[0081] Example 13. A method according to any one of the preceding or following examples or combinations of examples, wherein the tip radius of the first electrode is less than 100 mm, and wherein the tip radius of the second electrode is greater than 100 mm.

[0082] Example 14. The method of any preceding or following example or combination of examples, wherein the third time period is longer than the first time period and longer than the second time period.

[0083] Example 15. The method of any preceding or following example or combination of examples, wherein the rate at which the current is ramped down is less than the rate at which the current is ramped up during the first time period.

[0084] Example 16. A method for connecting metal substrates, the method comprising: providing a first electrode and a second electrode, wherein at least one feature of the first electrode is different from that of the second electrode; applying a pressing force to at least two stacked metal substrates using the first electrode and the second electrode, wherein at least one of the at least two metal substrates comprises aluminum or an aluminum alloy; and applying current by: ramping up the current at a ramp-up rate during a first time period; applying current at a welding level during a second time period after the first time period; and ramping down the current at a ramp-down rate during a third time period after the second time period, wherein the ramp-down rate is less than the ramp-up rate.

[0085] Example 17. A method according to any one of the preceding or following examples or combinations of examples, wherein the at least one feature includes a topography of the end of the first electrode, wherein a first metal substrate of the at least two metal substrates includes an aluminum plate, wherein a second metal substrate of the at least two metal substrates includes cast aluminum, wherein the method includes stamping the first electrode and imprinting a topography on the end of the first electrode, and wherein applying a clamping force includes contacting the first electrode with the first metal substrate.

[0086] Example 18. A method according to any one of the preceding or following examples or combinations of examples, wherein the at least one feature includes a terminal radius of the terminal end of the first electrode, wherein the terminal radius of the first electrode is smaller than the terminal radius of the second electrode, wherein the first metal substrate of the at least two metal substrates includes an aluminum plate, wherein the second metal substrate of the at least two metal substrates includes cast aluminum, and wherein applying the clamping force includes contacting the first electrode with the first metal substrate.

[0087] Example 19. The method according to any one of the preceding or following examples or combinations of examples, wherein the first time period is longer than the second time period.

[0088] Example 20. The method of any preceding or following example or combination of examples, wherein the third time period is longer than the first time period and longer than the second time period.

[0089] Example 21. A weld formed by a method according to any one of the preceding or following examples or combinations of examples.

[0090] The subject matter of the embodiment is specifically described herein to meet the statutory requirements, but such description is not necessarily intended to limit the scope of the claims. The claimed subject matter may be embodied in other ways, may include different elements or steps, and may be used in combination with other existing or future technologies. Such description should not be interpreted as implying any particular order or arrangement in or between various steps or elements, unless the order of the various steps or the arrangement of the elements is clearly described. Directional references such as "upper", "lower", "top", "bottom", "left", "right", "front" and "back" are intended to refer to the orientation illustrated and described in the figure (or each figure), and the parts and directions refer to the orientation. Throughout this disclosure, the reference numerals with letters refer to the specific examples of the elements, and the reference numerals without the accompanying letters refer to the elements in a general or collective manner. Therefore, as an example (not shown in the figure), the device "12A" refers to an instance of a device class, which can be collectively referred to as a device "12", and any of which can be generally referred to as a device "12". In each figure and description, similar numbers are intended to represent similar elements. As used herein, the meanings of "a", "an", and "the" include both singular and plural references unless the context clearly dictates otherwise.

[0091] In this description, reference is made to alloys identified by the AA number and other related designations, such as "Series" or "7xxx". For information on the numerical designation system most commonly used to name and identify aluminum and its alloys, see "International Alloy Designations and Chemical Composition Limitations for Wrought Aluminum and Wrought Aluminum Alloys" or "The Aluminum Association Register of Alloy Designations and Chemical Composition Limitations for Aluminum Alloys Used in Castings and Ingot Form", both published by the Aluminum Association.

[0092] As used herein, a plate generally refers to an aluminum product having a thickness of less than about 4 mm. For example, the thickness of the plate can be less than about 4 mm, less than about 3 mm, less than about 2 mm, less than about 1 mm, less than about 0.5 mm, or less than about 0.3 mm (e.g., about 0.2 mm).

[0093] As used herein, terms such as "cast metal product", "cast product", "cast aluminum alloy product" and the like are interchangeable and refer to products produced by methods such as die casting, mold casting or sand casting.

[0094] All ranges disclosed herein should be understood to include any and all sub-ranges contained therein. For example, the range of "1 to 10" should be considered to include any and all sub-ranges between (and including) a minimum value of 1 and a maximum value of 10; that is, all sub-ranges starting from a minimum value of 1 or greater (e.g., 1 to 6.1) and ending with a maximum value of 10 or less (e.g., 5.5 to 10). Unless otherwise stated, when referring to the composition amount of an element, the expression "up to" means that the element is optional and includes a zero percent composition of the particular element. Unless otherwise stated, all component percentages are weight percentages (wt.%).

[0095] The various aspects described above are only possible examples of embodiments, and are stated only for the purpose of clearly understanding the principles of the present disclosure. Without significantly departing from the spirit and principles of the present disclosure, many variations and modifications may be made to the above-mentioned (multiple) embodiments. All such modifications and variations are expected to be included herein within the scope of the present disclosure, and all possible claims for the combination of individual aspects or elements or steps are expected to be supported by the present disclosure. In addition, although specific terms are used herein and in the claims that follow, they are used only in a general and descriptive sense, and are not intended to limit the purpose of the described invention, nor are they intended to limit the purpose of the claims that follow.

Claims

1. A method for connecting a metal substrate, the method comprising: providing a first electrode and a second electrode, wherein at least one characteristic of the first electrode is different from that of the second electrode; Applying a compressive force to at least two stacked metal substrates using the first electrode and the second electrode, wherein at least one of the at least two stacked metal substrates comprises aluminum or an aluminum alloy; applying a current at a first level during a first time period and ramping the current from the first level to a second level greater than the first level; After the first time period, applying current at the second level for a second time period; and After the second time period, the current is ramped down from the second level during a third time period, wherein the rate at which the current is ramped down is less than the rate at which the current is ramped up during the first time period.

2. The method according to claim 1, wherein: A first metal substrate of the at least two stacked metal substrates comprises cast aluminum, and wherein a second metal substrate of the at least two stacked metal substrates comprises an aluminum plate.

3. The method according to claim 1, wherein: The first time period is shorter than the third time period.

4. The method according to claim 1, wherein: The third time period is longer than the first time period and longer than the second time period.

5. The method according to claim 1, wherein: The at least one feature comprises a topography of a terminal end of a first electrode, and wherein the method comprises stamping the first electrode and printing the topography on the terminal end of the first electrode.

6. The method according to claim 5, wherein: A first metal substrate of the at least two stacked metal substrates comprises an aluminum plate, wherein a second metal substrate of the at least two stacked metal substrates comprises cast aluminum, and applying the pressing force comprises contacting the first electrode with the first metal substrate.

7. The method according to claim 1, wherein: The at least one feature comprises a terminal radius of a terminal end of the first electrode, and wherein the terminal radius of the first electrode is smaller than a terminal radius of the second electrode.

8. The method according to claim 7, wherein: A first metal substrate of the at least two stacked metal substrates comprises an aluminum plate, wherein a second metal substrate of the at least two stacked metal substrates comprises cast aluminum, and applying the pressing force comprises contacting the first electrode with the first metal substrate.

9. A method for connecting a metal substrate, the method comprising: providing a first electrode and a second electrode, wherein at least one characteristic of the first electrode is different from that of the second electrode; Applying a compressive force to at least two stacked metal substrates using the first electrode and the second electrode, wherein at least one of the at least two stacked metal substrates comprises aluminum or an aluminum alloy; applying a current at a first level during a first time period and ramping the current from the first level to a second level greater than the first level; After the first time period, applying current at a third level for a second time period; and After the second time period, the current is ramped down from the third level during a third time period.

10. The method according to claim 9, wherein: The third level is greater than the second level.

11. The method according to claim 9, wherein: The at least one feature comprises a terminal radius of a terminal end of the first electrode, and wherein the terminal radius of the first electrode is smaller than a terminal radius of the second electrode.

12. The method according to claim 11, wherein: A first metal substrate of the at least two stacked metal substrates comprises an aluminum plate, wherein a second metal substrate of the at least two stacked metal substrates comprises cast aluminum, and applying the pressing force comprises contacting the first electrode with the first metal substrate.

13. The method according to claim 11, wherein: The first electrode has a tip radius of less than 100 mm, and wherein the second electrode has a tip radius of greater than 100 mm.

14. The method according to claim 9, wherein: The third time period is longer than the first time period and longer than the second time period.

15. The method according to claim 9, wherein: The rate at which the current is ramped down is less than the rate at which the current is ramped up during the first time period.

16. A method for connecting metal substrates, the method comprising: providing a first electrode and a second electrode, wherein at least one characteristic of the first electrode is different from that of the second electrode; applying a compressive force to at least two stacked metal substrates using the first electrode and the second electrode, wherein at least one of the at least two stacked metal substrates comprises aluminum or an aluminum alloy; and The current is applied by: During a first time period, ramping up the current at a ramp rate; applying current at a welding level during a second time period after the first time period; and During a third time period after the second time period, the current is ramped down at a ramp-down rate, wherein the ramp-down rate is less than the ramp-up rate.

17. The method according to claim 16, wherein: The at least one feature comprises a topography of an end of the first electrode, wherein a first metal substrate of the at least two stacked metal substrates comprises an aluminum plate, wherein a second metal substrate of the at least two stacked metal substrates comprises cast aluminum, wherein the method comprises stamping the first electrode and imprinting the topography on the end of the first electrode, and wherein applying the compacting force comprises contacting the first electrode with the first metal substrate.

18. The method according to claim 16, wherein: The at least one feature comprises a terminal radius of a terminal end of the first electrode, wherein the terminal radius of the first electrode is less than a terminal radius of the second electrode, wherein a first metal substrate of the at least two stacked metal substrates comprises an aluminum plate, wherein a second metal substrate of the at least two stacked metal substrates comprises cast aluminum, and wherein applying the compressive force comprises contacting the first electrode with the first metal substrate.

19. The method according to claim 16, wherein: The first time period is longer than the second time period.

20. The method according to claim 16, wherein: The third time period is longer than the first time period and longer than the second time period.

21. A weld formed by the method of any one of claims 1, 9 or 16.

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