RESTRAINT METHODS.

Abstract

Fastening methods are provided. One method comprises contacting a fastener with a first layer of an assembly at a first location. The assembly comprises the first layer, a third layer, and a second layer positioned between the first and third layers. The first layer, the third layer, and the fastener are electrically conductive. The second layer defines a gap, and the first location is in communication with this gap. Electrical communication is established between the assembly and the fastener. The first layer is fastened to the third layer through the gap in the second layer by the fastener. The fastening comprises resistance welding the fastener to the third layer.

Description

RESTRAINT METHODS FIELD OF INVENTION The present invention relates to clamping methods. BACKGROUND OF THE INVENTION Current methods for fastening workpieces together, such as clamping sheets together, may include the use of self-drilling rivets and / or flux-cored rivets. Other fastening methods may utilize a resistance spot welding system. There are challenges associated with using rivets to fasten workpieces together. SUMMARY OF THE INVENTION In one aspect, a fastening method is provided. The method comprises contacting a fastener with a first layer of an assembly at a first location. The assembly comprises the first layer, a third layer, and a second layer positioned between the first and third layers. The first layer, the third layer, and the fastener are electrically conductive. The second layer defines a space, and the first location is in communication with this space. An electrical connection is established between the assembly and the fastener. The first layer is fastened to the third layer through the space in the second layer by the fastener. The fastening comprises resistance welding the fastener to the third layer. In another aspect, a clamping method is provided. The method comprises contacting a fastener with a first layer of an assembly at a first location. The assembly comprises the first layer, a third layer, and a second layer positioned between the first and third layers. The first layer, the third layer, and the fastener are electrically conductive. The second layer defines a space, and the first location is in communication with this space. The material of the second layer differs from the material of the first layer or the material of the third layer. An electrode of a resistance welding device is made contact with the fastener, and an electrically conductive path is formed between the electrode, the fastener, and the assembly. The first layer is clamped to the third layer. The clamping comprises resistance welding the fastener to the third layer through the space in the second layer using the electrode.A metallurgical bond is formed between the backer and the third layer. The second layer is bonded to either the first or third layer. The bonding process involves resistance welding the second layer to the first or third layer using an electrode. The metallurgical bond is formed between the second layer and either the first or third layer. It is understood that the inventions disclosed and described in this specification are not limited to the aspects summarized herein. The reader will appreciate the foregoing details, as well as others, after considering the following detailed description of various non-limiting and non-exhaustive aspects in accordance with this specification. BRIEF DESCRIPTION OF THE DRAWINGS The features and advantages of the examples, and how to achieve them, will become clearer, and the examples will be better understood, by reference to the following description taken in conjunction with the accompanying drawings, where: Figure 1 is a top view of a non-limiting modality form of MA / a / ZUZZ / Ul There is a first layer, a second layer, and a third layer arranged side by side according to the present disclosure; Figure 2 is a cross-sectional side view of a non-limiting modality of a fastener and assembly formed from the layers of Figure 1 arranged in a stack according to the present disclosure; Figure 3 is a cross-sectional side view of the fastener of Figure 2 in contact with the assembly of Figure 2, further showing electrodes of a resistance spot rivet welding system mating with the fastener and assembly; Figure 4 is a cross-sectional side view of the fastener and assembly of Figure 3 after deformation of a first layer of the assembly; Figure 5 is a cross-sectional side view of the fastener and assembly of Figure 4, where a metallurgical bond was formed between the fastener and a third layer of the assembly; Figure 6 is a cross-sectional side view of the fastener and assembly of Figure 5, where a metallurgical bond was formed between a second layer and the third layer of the assembly; and Figure 7 is a cross-sectional side view of the fastener and assembly of Figure 5, where a metallurgical bond was formed between the first layer and a second layer of the assembly. The corresponding reference characters indicate corresponding parts along the various views. The examples shown herein illustrate certain non-limiting forms of embodiment, and such examples shall not be construed as limiting the scope of the appended claims in any way. DETAILED DESCRIPTION OF NON-LIMITED MODALITIES This document describes and illustrates various examples to provide a general understanding of the structure, function, and use of the disclosed systems, apparatus, and methods. The various examples described and illustrated herein are neither limiting nor exhaustive. Therefore, the inventions are not limited by the description of the various non-limiting and non-exhaustive examples disclosed herein. Rather, the inventions are defined solely by the claims. The functions and features illustrated and / or described in connection with various examples may be combined with the functions and features of other examples. Such modifications and variations are intended to be included within the scope of this specification.As such, the claims may be amended to include any functions or features expressly or inherently described in this specification or otherwise expressly or inherently supported by it. Furthermore, the applicant reserves the right to amend the claims to affirmatively reject functions or features that may be present in the prior art. The various non-limiting embodiments disclosed and described in this specification may comprise, consist of, or essentially consist of the functions and features as described in various ways herein. Any reference herein to “various forms of modality,” “some forms of modality,” “a form of modality,” or a similar phrase means that a particular function, structure, or characteristic described in relation to the example is included in at least one form of modality. Therefore, occurrences of the phrases “in various forms of modality,” “in some forms of modality,” “in a form of modality,” or similar phrases in the descriptive memory do not necessarily refer to the same form of modality. Furthermore, the particular functions, structures, or characteristics described may be combined in any appropriate way in one or more forms of modality. Thus, the particular functions, structures, or characteristics illustrated or described in relation to one form of modality may be combined, in whole or in part, with the functions, structures, or characteristics of one or more other forms of modality, among others.It is intended that such modifications and variations be included within the scope of the present forms of modality. In this specification, unless otherwise stated, all numerical parameters are understood to be preceded and modified in all cases by the expression "around," where the numerical parameters possess the characteristic of inherent variability due to the underlying measurement techniques used to determine the numerical value of the parameter. At a minimum, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter described herein shall at least be interpreted in light of the number of significant digits reported and by applying customary rounding techniques. Furthermore, any numerical range mentioned herein includes all subranges within that range. For example, a range of “1 to 10” includes all subranges between (and inclusive of) the minimum value of 1 and the maximum value of 10; that is, it has a minimum value equal to or greater than 1 and a maximum value equal to or less than 10. Any maximum numerical limitation mentioned in this specification is intended to include all limitations IVIA / a / ZUZZ / UI 1 l Lower numerical ZZ ranges included herein, and any minimum numerical limitation mentioned herein is intended to include all upper numerical limitations included herein. Accordingly, the applicant reserves the right to amend this specification, including the claims, to expressly mention any subrange included within the expressly mentioned ranges. All such ranges are inherently described herein. The grammatical articles “un,” “una,” “el,” and “la,” as used herein, include “at least one” or “one more,” unless otherwise indicated, even if “at least one” or “one more” is explicitly used in certain cases. Therefore, the above grammatical articles are used herein to refer to one or more of the identified items (i.e., “at least one”). Furthermore, the use of a singular noun includes the plural, and the use of a plural noun includes the singular, unless the context of use requires otherwise. As used herein, a referenced element or region being “intermediate” between two other elements or regions means that the referenced element / region is positioned between the other two elements / regions but is not necessarily in contact with them. Accordingly, for example, a referenced element being “intermediate” between a first element and a second element may or may not be adjacent to or in contact with the first and / or second elements, and other elements may be positioned between the referenced element and the first and / or second elements. Self-drilling rivets and / or flow-pierced rivets may not be able to penetrate and / or fasten various high-hardness steels and aluminum materials. Therefore, the applications of self-drilling rivets and / or flow-pierced rivets may be limited. Resistance Spot Rivet (RSRT) technology enables the joining of a variety of parts and assemblies made from diverse material combinations, such as high-hardness steels and aluminum. RSR™ technology uses rivets (e.g., metal rivets) of various geometries and materials to offer a selection of solutions tailored to each joining scenario. With RSR™ technology, rivets can be applied to a joint using conventional resistance spot welding guns (e.g., transguns). These welding guns can be combined with a robotic manipulator and / or a pedestal welder and integrated into a system of auxiliary components.The components can perform operations including, for example, rivet handling, rivet sorting and orientation, rivet distribution and feeding, rivet transfer, and rivet presentation to the welding gun electrode. Each joint created by an RSR™ rivet system typically consumes a single rivet. However, when materials are joined with rivets, the rivet head and / or tail typically protrude beyond the sheet metal edge of the material being joined. The distance the rivet protrudes from the sheet metal edge can lead to unwanted interference in subsequent manufacturing stages. For example, in automotive applications, rivets placed in window frames, roofs, and door openings can interfere with seals placed over the rivets. Therefore, the seals may need to incorporate intricate features to properly seal the rivets, and / or the moisture-tightness of the seal may be reduced, potentially rendering rivets unsuitable for these applications.Therefore, this disclosure provides a method that can reduce the distance the rivet protrudes from the material's sheet line, so that the rivets will minimally, if at all, interfere with subsequent manufacturing steps. For example, the distance the rivets protrude from the material's sheet line may not interfere, or may only minimally, with seals in window frames and door openings, and / or reduce the complexity of seal design. In various non-limiting ways, this disclosure can allow for a reduced flange width of an automotive window frame assembly, thereby decreasing the weight of the window frame assembly and / or improving visibility through the window frame. Accordingly, this disclosure enables the efficient and effective use of rivets in the desired applications. With reference to Figure 1, a non-limiting embodiment of a first layer 106, a second layer 108, and a third layer 110 is provided. Layers 106, 108, and 110 can be configured to form an assembly 104 as described with reference to Figure 2. Each of the first layer 106 and the third layer 110 can comprise a metal or a metal alloy. Furthermore, each of the first layer 106 and the third layer 110 can be electrically conductive. For example, the first layer 106 and the third layer 110 can be configured to communicate electrically with a resistance spot welding system. The first layer 106 and the third layer 110 can comprise the same material or different materials.In various non-limiting forms, the first layer 106 and the third layer 110 may comprise at least one of aluminum, an aluminum alloy, iron, an iron alloy (for example, a steel), titanium, and a titanium alloy. IVIA / a / ZUZZ / UI 1 1 The second layer 108 may comprise, for example, at least one of a metal, a metal alloy, and a composite material. The second layer 108 may be electrically conductive or electrically insulating. The composite material may comprise at least one of a polymer and a laminated sheet or panel (for example, the REYNOBOND® composite panel, which includes two coated aluminum sheets laminated to either side of a fire-resistant core). The second layer 108 and the third layer 110 may comprise the same or different materials, and the second layer 108 and the first layer 106 may comprise the same or different materials. In various non-limiting embodiments, the second layer 108 comprises a different material than at least one of the first layer 106 and the third layer 110. For example, the second layer 108 may comprise a material that is not weldable to at least one of the first layer 106 and the third layer 110. In various non-limiting embodiments, the first layer 106 may comprise aluminum (for example, the first layer 106 may be an aluminum sheet) and the third layer 110 may comprise steel (for example, the third layer 110 may be a steel sheet). In various non-limiting embodiments, the second and third layers 108 and 110 comprise steel, which may be of the same grade or different grades. Regardless of the grade of steel, the second and third layers 108 and 110 may comprise materials that can be welded together. In other non-limiting embodiments, the first and second layers 106 and 108 comprise aluminum, which may be of the same grade or different grades. Regardless of the grade of aluminum, the first and second layers 106 and 108 may comprise materials that can be welded together.In certain non-limiting forms, the second layer 108 comprises a composite material, which may not be weldable to either the first layer 106 or the third layer 110. The second layer 108 can define a space 114 (also shown in Figure 3). Space 114 can be defined by removing at least a portion of the second layer 108 to form the space 114. For example, removing at least a portion of the second layer 108 can involve stamping, machining, cutting, grinding, punching, and / or drilling the second layer 108. Space 114 can create a void suitable for receiving a portion of the first layer 106. Therefore, space 114 can allow for deformation of the first layer 106 within space 114. Furthermore, space 114 can reduce the weight of assembly 104, which, for example, in automotive applications, can increase fuel economy and reduce the cost of assembly 104. Space 114 in the second layer 108 may comprise a dimension, d2, not greater than 200 mm, such as, for example, not greater than 100 mm, not greater than 50 mm, not greater than 40 mm, not greater than 30 mm, not greater than 25 mm, not greater than 20 mm, or not greater than 15 mm. The dimension, d2, may be at least 5 mm, such as, for example, at least 10 mm, at least 12 mm, at least 15 mm, at least 20 mm, at least 25 mm, at least 30 mm, at least 40 mm, at least 50 mm, or at least 75 mm. For example, the dimension, d2, may be in the range of 5 mm to 200 mm, such as, for example, 15 mm to 75 mm, 10 mm to 15 mm, 12 mm to 15 mm, 5 mm to 50 mm, 20 mm to 100 mm, 25 mm to 100 mm, or 25 mm to 50 mm. In various non-limiting embodiments, the second layer 108 may comprise multiple spaces (not shown). In certain non-limiting embodiments, the multiple spaces may be arranged substantially linearly near an edge of the assembly 104.In various non-limiting ways, the dimension, d2, can be adjusted to reduce the weight of assembly 104 and / or achieve a desired spacing of fasteners and / or metallurgical joints. One non-limiting embodiment of a fastening method according to this disclosure may comprise placing the second layer 108 intermediate between the first layer 106 and the third layer 110 to form the assembly 104 as illustrated in Figure 2. For example, the second layer 108 may be placed in contact with the first layer 106 and the third layer 110. In various non-limiting embodiments, an additional layer or layers (not shown) may be placed within the assembly 104. In certain non-limiting embodiments, the outermost layers of the assembly 104 may be electrically conductive.In other non-limiting embodiments, an outermost layer of assembly 104 may be electrically insulating and comprise a pilot hole through the electrically insulating outermost layer, so that a fastener may pass through the pilot hole and make contact with an electrically conductive layer of assembly 104. The first layer 106 may comprise a thickness, ti, the second layer 108 may comprise a thickness, t2, and the third layer 110 may comprise a thickness, t3. In various non-limiting embodiments, each thickness, ti, t2, and t3, may be in a range from 0.1 mm to 20 mm, such as, for example, from 0.25 mm to 5 mm, from 0.8 mm to 3.5 mm, from 0.5 mm to 3 mm, from 0.8 mm to 4 mm, from 0.5 mm to 5 mm, from 0.75 mm to 2 mm, from 2 mm to 15 mm, from 1 mm to 10 mm, from 1 mm to 5 mm, or from 5 mm to 10 mm. For example, the thickness, ti, may be 1 mm, and each of the thicknesses, t2 and t3, may be 1.6 mm. In various non-limiting embodiments where a selected layer comprises steel, the thickness of the selected steel layer may be in the range of 0.5 mm to 3.0 mm. In various non-limiting embodiments where a selected layer comprises aluminum, the thickness of the selected aluminum layer may be in the range of 0.8 mm to 3.5 mm.In certain non-limiting forms where a selected layer comprises a composite material, the thickness of the selected composite material layer may be in a range of 0.8 mm to 4.0 mm. A welding adhesive may be deposited on at least one of the first layer 106, the second layer 108, and the third layer 110 before forming the assembly 104. The welding adhesive may be intermediate between the first layer 106 and the second layer 108 and / or intermediate between the second layer 108 and the third layer 110 in the assembly 104. A welding adhesive may not inhibit a welding operation performed on the assembly 104. The welding adhesive may be cured to form a bond between the desired layers. For example, the welding adhesive may be used between layers comprising different materials (e.g., materials that cannot be welded together). In various non-limiting embodiments, the welding adhesive may be cured after clamping the first layer 106 to the third layer 110 with the clamp 102 as described with reference to Figure 5 below. The dimension, d2, can be at least as large as a diameter, di, of the head 116 of the fastener 102, such as, for example, at least 1 mm larger than the diameter, di; at least 2 mm larger than the diameter, di; at least 3 mm larger than the diameter, di; at least 4 mm larger than the diameter, di; at least 5 mm larger than the diameter, di; at least 10 mm larger than the diameter, di; at least 15 mm larger than the diameter, di; at least 20 mm larger than the diameter, di; or at least 25 mm larger than the diameter, di. For example, the dimension, d2, can be sized to allow a desired deformation of the first layer 106 to create a recess (for example, the recess 428 described with respect to Figure 4 below) that can receive the MA / a / ZUZZ / UI There less partially the head 116 of the fastener 102. In addition, in various non-limiting ways, the thickness, t2, can be dimensioned to allow a desired deformation of the first layer 106 to create a recess that can receive at least partially the head 116 of the fastener 102. The fastener 102 can be configured to contact and clamp layers 106, 108, and 110 of assembly 104 together using a resistance spot rivet welding process. The fastener 102 comprises a head 116 and a stem 118, as shown in Figure 3. The head 116 can be configured to engage an electrode 324 of a resistance spot rivet welding system, as illustrated in Figure 3, for example. Furthermore, the head 116 can be configured to contact a layer of assembly 104 after installation, as described with reference to Figure 5.For example, again with reference to Figure 2, the head 116 can be configured to engage with a layer of the assembly 104 (e.g., applying a clamping force) and penetrate minimally, if at all, through the engaged layer, whereas the stem 118 can be configured to pierce through the engaged layer during a resistance spot rivet welding process. Furthermore, the stem 118 can be metallurgically bonded to a layer of the assembly 104. The head 116 can extend around a periphery of the stem 118 and can comprise, for example, an annular shape. In various non-limiting embodiments, a cavity 122 can extend through the head 116 and at least partially into the stem 118. Also, in various non-limiting embodiments, the stem 118 can taper towards an end 120 of the fastener 102. The end 120 can be configured to engage and apply localized pressure to a layer of the assembly 104. The fastener 102 may comprise a metal or a metal alloy. For example, the fastener 102 may comprise an electrically conductive material suitable for withstanding a resistance spot welding process for riveting. In various non-limiting embodiments, the fastener 102 may comprise at least one of aluminum, an aluminum alloy, iron, an iron-titanium alloy, and a titanium alloy. For example, in certain non-limiting embodiments, the fastener 102 may comprise at least one of iron, an iron-titanium alloy, and a titanium alloy. In various non-limiting embodiments, the fastener 102 may comprise the same material as the third layer 110. For example, each of the fastener 102 and the third layer 110 may comprise a material that is weldable to the other. For example, the fastener 102 and the third layer 110 may comprise steel.In various non-limiting forms, when the fastener 102 comprises aluminum, a pilot hole can be provided in the first layer 106. In various non-limiting forms, the fastener 102 is a rivet. The head 116 of the fastener 102 may comprise a diameter, di, of at least 4 mm, such as, for example, at least 5 mm, at least 6 mm, at least 7 mm, at least 10 mm, at least 12 mm, at least 14 mm, at least 15 mm, at least 16 mm, at least 18 mm, at least 20 mm, at least 22 mm, at least 24 mm, or at least 25 mm. In various non-limiting forms, the head 102a of the fastener 102 may comprise a diameter, di, not greater than 30 mm, not greater than 25 mm, not greater than 24 mm, not greater than 22 mm, not greater than 20 mm, not greater than 18 mm, not greater than 16 mm, such as, for example, not greater than 15 mm, not greater than 14 mm, not greater than 12 mm, not greater than 10 mm or not greater than 7 mm.For example, in certain non-limiting forms, the head 116 of the fastener 102 may comprise a diameter, di, in a range of 4 mm to 30 mm, such as, for example, 5 mm to 25 mm, 10 mm to 18 mm, 10 mm to 14 mm, 14 mm to 18 mm, 20 mm to 25 mm, or 12 mm to 14 mm. With reference to Figure 4, the head 116 cannot initially pierce through a layer of the assembly 104 to which the fastener 102 is attached after installation, and therefore the distance, ds, by which the head 116 extends protrudes from the surface of the layer. In various non-limiting embodiments, the distance, ds, may be at least 0.5 mm, such as, for example, at least 1 mm, at least 1.5 mm, at least 2 mm, or at least 3 mm. In various non-limiting embodiments, the distance, ds, may be no greater than 5 mm, such as, for example, no greater than 4 mm, no greater than 3 mm, no greater than 2 mm, or no greater than 1.5 mm. For example, the distance, ds, may be in the range of 0.5 mm to 5 mm, such as, for example, from 1 mm to 3 mm or from 1 mm to 2 mm.The space 114 and the distance, ds, by which the head 116 extends can be dimensioned relative to each other, so that when the fastener 102 is installed in the assembly 104, the head 116 protrudes minimally, if at all, beyond a sheet line, Sh, of the first layer 106. For example, the distance, ds, of the head 116 can be selected based on the thickness, ts, of the second layer 108, so that when the fastener 102 is installed in the assembly 104, the first layer 106 can be deformed in the space 114 in the second layer 108 to form the recess 428, so that the head 116 can be received by the recess 428 and protrudes minimally, if at all, beyond the sheet line, Sh, of the first layer 106. As used herein, and as illustrated in the In Figure 5, the phrase “sheet line” refers to an imaginary line that extends along the outer surface of a sheet when assembly 104 is viewed in cross-section. Again, with reference to Figure 2, the stem 118 can be extended a distance, d4, which can be at least 3 mm, such as, for example, at least 4 mm, at least 5 mm, or at least 6 mm. In various non-limiting embodiments, the distance, d4, can be no greater than 10 mm, such as, for example, no greater than 9 mm, no greater than 8 mm, or no greater than 6 mm. For example, the distance, d4, can be in the range of 3 mm to 10 mm, such as, for example, from 4 mm to 9 mm or from 5 mm to 8 mm. The stem 118 may have a diameter of no more than 10 mm, such as, for example, no more than 7 mm, no more than 6 mm, no more than 5 mm, no more than 4 mm, or no more than 3 mm. In various non-limiting embodiments, the stem 118 may have a diameter of at least 1 mm, such as, for example, at least 2 mm, at least 3 mm, at least 4 mm, at least 5 mm, at least 6 mm, or at least 7 mm. For example, the stem 118 may have a diameter in the range of 1 mm to 10 mm, such as, for example, from 2 mm to 5 mm, from 2 mm to 7 mm, or from 3 mm to 6 mm. In certain modes, the diameter of the shank 118 may decrease in a direction away from the head 116. The diameter of the shank 118 may be smaller than the diameter of an electrode in a resistance spot rivet welding system, so that the shank 118 can apply a greater localized force to a layer of the assembly 104 to deform the layer. With reference to Figure 3, the fastener 102 can contact the first layer 106 of the assembly 104 at a first location 312. For example, the stem 118 can contact the first layer 106 at the first location 312. The use of the stem 118 can provide greater localized pressure at the first location 312 than if a first electrode 324 of the system There, resistance spot rivet welding will be applied directly to the first location 312. The first location 312 may be in communication with the space 114. The first electrode 324 may be made contact with the fastener 102 and a second electrode 326 of the resistance spot rivet welding system may be made contact with the third layer 110 to apply a clamping force to the assembly 104 and the fastener 102. In various non-limiting forms, before making contact between the assembly 104 and the fastener 102, at least a portion of the second layer 108 is removed to form the space 114. In various non-limiting embodiments, the yield strength of the first layer 106 may be lower than the yield strength of the third layer 110. Therefore, if a compressive force and / or heat is applied to the assembly 104, the first layer 106 may deform earlier and / or to a greater degree than the third layer 110. In various non-limiting embodiments, the thickness, ti, of the first layer 106 may be dimensioned relative to the third layer 110, such that if a compressive force and / or heat is applied to the assembly 104, the first layer 106 may deform earlier and / or to a greater degree than the third layer 110. Depending on the yield strength of the first layer 106 and / or the thickness, ti, of the first layer 106, the first layer 106 may deform in a space 114 defined in the second layer 108. The deformation of the first layer 106 may create a recess 428 suitable for receiving the head 116 of the fastener 102 as described with respect to Figure 4 below. Again, with reference to Figure 3, electrical communication can be established between assembly 104 and fastener 102. For example, the first electrode 324 and a second electrode 326 can form an electrically conductive path between electrodes 324 and 326, fastener 102, and assembly 104. This electrically conductive path can be suitable for conducting an electric current through electrodes 324 and 326, fastener 102, and assembly 104, which can resistively heat and / or metallurgically bond at least two layers of assembly 104, and / or resistively heat and / or metallurgically bond a fastener to one layer of assembly 104. In various non-limiting configurations, the second electrode 326 can be a cooled electrode, such as, for example, a cooled copper electrode. Therefore, the temperature of the third layer 110, which is in contact with the second electrode 326, can be maintained at a lower temperature than that of the first layer 106 at the first location 312. Thus, the resistive heating caused by the electric current can be concentrated in the first layer 106. The first layer 106 can be clamped to the third layer 110 through the gap 114 in the second layer 108 using the clamp 102. For example, the clamp 102 can be resistively welded to the third layer 110 by applying an electrical potential across the assembly 104 and the clamp 102 and by passing an electric current through them. In various non-limiting modes, the electrical potential can be applied across the assembly 104 and the clamp 102 using the electrodes 324 and 326 of the resistance spot rivet welding system. The electric current can resistively heat and soften the first location 312 of the first layer 106, so that the pressure applied by the end 120 of the fastener 102 to the first layer 106 deforms the first layer 102 in space 114, forming a recess 428 as illustrated in Figure 4.Heating the first layer 102 at the first location 312 may allow high-strength materials (e.g., high-strength aluminum and / or high-strength steel) to deform with minimal cracking and / or fracturing of the first layer 106, if any. In various non-limiting modes, space 114 may allow further heating of the first layer 106 at the first location 312, since the second layer 108 is not in direct contact with the first location 312 and therefore cannot conduct heat directly from the first location 312. With reference to Figure 5, the clamping force can be maintained to push the fastener 102 through the first layer 106 at the first location 312 into the third layer 110. In various non-limiting modes where the fastener 102 and the first layer 106 are different materials, the fastener 102 may not be welded to the first layer 106 and will pierce through the first layer 106 via the gap 114 into the third layer 110. The fastener 102 can then be pushed into contact with the third layer 110. The fastener 102 can be resistance-welded to the third layer 110, forming a metallurgical bond 530 between the fastener 102 and the third layer 110.In various non-limiting forms in which the fastener 102 and the third layer 110 comprise materials that can be welded together, the fastener 102 can be welded to the third layer 110 and secure the first layer 106 intermediate between the head 116 of the fastener 102 and the third layer 110. The head 114 of the fastener 102 may be at least partially positioned within the space 114 and the recess 428 formed therein after deforming the first layer 106. For example, after fastening the first layer 106 to the third layer 110 through the space 114 in the second layer 108 with the fastener 102, the head 116 of the fastener 102 may protrude a distance, ds, beyond the foil line, S1i, of the first layer 106 not greater than 2 mm, such as, for example, not greater than 1.5 mm, not greater than 1 mm, not greater than 0.75 mm, not greater than 0.5 mm, not greater than 0.4 mm, or not greater than 0.25 mm. In various non-limiting forms, the fastener 102 may not protrude beyond the foil line, S1i, of the first layer 106. With reference to Figure 6, electrodes 324 and 326 can be repositioned so that the first electrode 324 engages a second location 612 in the first layer 106 and applies another electrical potential across the assembly 104, thereby resistance welding the second layer 108 to the third layer 110 and forming a metallurgical bond 630 between them, as illustrated in Figure 6, or resistance welding the second layer 108 to the first layer 106 and forming a metallurgical bond 730 between them, as illustrated in Figure 7. Therefore, in various non-limiting modes, the same electrodes 324 and 326 can be used for the resistance spot welding process of rivets and also for the resistance spot welding process.Therefore, minimal capital equipment may be required and process efficiency may be increased by performing resistance spot rivet welding and resistance spot welding using the same 324 and 326 electrodes and associated welding equipment. Whether the second layer 108 can be welded to the first layer 106 or the third layer 110 depends on the material composition of layers 106, 108, and 110, as well as the welding parameters. For example, if the first layer 106 comprises a material that can be welded to the second layer 108, then the first layer 106 and the second layer 108 can be welded together after applying the desired electrical potential. If the third layer 110 comprises a material that can be welded to the second layer 108, then the third layer 110 and the second layer 108 can be welded together after applying the desired electrical potential. In various non-limiting forms, if the first layer 106 and the third layer 110 comprise a material that cannot be welded to the second layer 108, the first layer 106 and the third layer 110 cannot be welded to the second layer 108.In certain non-limiting forms, the material of the second layer 108 differs from a material of the first layer 106 or from a material of the third layer 110. The process of attaching the first layer 106 to the third layer 110 by resistance welding a fastener to the third layer 110 can be repeated throughout the assembly 104 as desired. Furthermore, the process of metallurgically joining the second layer 108 to the first layer 106 and / or the third layer 110, as illustrated in Figures 6 and 7, can be repeated as desired. In certain non-limiting embodiments, the process of attaching the first layer 106 to the third layer 110 by resistance welding a fastener to the third layer can be alternated with the process of metallurgically joining the second layer 108 to the first layer 106 and / or the third layer 110, as illustrated in Figures 6 and 7. Therefore, the non-limiting modality forms of the fastening method according to this disclosure can fasten materials of various compositions together and result in a reduced degree of fastener protrusion beyond a sheet line of a layer to which the fastener is mated. Furthermore, the modality forms of the fastening method according to this disclosure can permit a desired weld quality, such that a Grade A weld can be achieved between a fastener and a layer. Various aspects of certain non-limiting forms of the inventions covered by this disclosure include, among others, the aspects listed in the following numbered clauses. 1. A method of restraint, wherein the method comprises: putting a fastener in contact with a first layer of an assembly at a first location, wherein the assembly comprises the first layer, a third layer and a second layer placed intermediate between the first layer and the third layer, wherein the first layer, the third layer and the fastener are electrically conductive, and wherein the second layer defines a space and the first location is in communication with the space; forming an electrical communication between the assembly and the fastener; and fastening the first layer to the third layer through the space in the second layer with the fastener, wherein the fastening comprises resistance welding the fastener to the third layer. 2. The method according to clause 1, further comprising before contact, removing at least a portion of the second layer to form the space, wherein the removal comprises one or more stamping, machining, cutting, grinding, punching and drilling. 3. The method according to clause 2, which further comprises, before contact, placing the second intermediate layer between the first layer and the third layer to provide the assembly. 4. The method according to any of clauses 1-3, wherein the fastener comprises a head and a shank, and wherein contacting the fastener with the first layer at the first location comprises contacting the shank with the first layer at the first location. 5. The method according to clause 4, wherein attaching the first layer to the third layer through the space in the second layer further comprises deforming the first layer at the first location in space in the second layer. 6. The method according to clause 5, wherein the head of the fastener is placed at least partially within a recess formed in the first layer after deforming the first layer. 7. The method in accordance with clause 6, wherein after fastening the first layer to the third layer through the space in the second layer with the fastener, the head of the fastener protrudes no more than 1.5 mm beyond a surface of the assembly. 8. The method in accordance with any of clauses 1-7, wherein the space in the second layer comprises a dimension not greater than 50 mm. 9. The method in accordance with any of clauses 1-8, wherein each of the first layer, the third layer and the fastener comprises a metal or a metal alloy, and the second layer comprises one or more of a metal, a metal alloy and a composite material. 10. The method in accordance with any of clauses 1-9, wherein a yield strength of the first layer is less than a yield strength of the third layer. 11. The method in accordance with any of clauses 1-10, wherein the first layer and the third layer comprise different materials. 12. The method in accordance with any of clauses 1-11, wherein the second layer and the first layer or the third layer comprise the same material. 13. The method according to clause 12, further comprising resistance welding the second layer to the first or third layer, thereby forming a metallurgical bond. 14. The method in accordance with any of clauses 1-13, wherein resistance welding the fastener to the third layer comprises: apply an electrical potential across the assembly and fastener, which heats by resistance and softens the first location of the first layer; push the fastener through the first layer at the first location into the third layer; and bring the fastener and the third layer into contact and resistance weld the fastener to the third layer, forming a metallurgical bond between the fastener and the third layer. 15. The method according to clause 14, wherein applying an electrical potential through the assembly and the fastener comprises bringing the fastener into contact with an electrode of a resistance welding device. 16. The method according to clause 15, further comprising resistance welding the second layer to the first or third layer using the electrode of the resistance welding device, thereby forming a metallurgical bond between the second layer and the first or third layer. 17. The method in accordance with any of clauses 1-16, which further comprises: deposit a welding adhesive onto one or more of the first layer, the second layer, and the third layer; and cure the adhesive after clamping the first layer to the third layer through the gap in the second layer with the clamp. 18. A fastening method, comprising: putting a fastener in contact with a first layer of an assembly at a first location, wherein the assembly comprises the first layer, a third layer and a second layer positioned between the first layer and a third layer, wherein the first layer, the third layer and the fastener are electrically conductive, wherein the second layer defines a space and the first location is in communication with the space, and wherein a material of the second layer differs from a material of the first layer or a material of the third layer; to bring into contact an electrode of a resistance welding device IVIA / a / ZUZZ / UI 1 l with the fastener and form an electrically conductive path between the electrode, the fastener and the assembly; securing the first layer to the third layer, wherein the securing comprises resistance welding the securing member to the third layer through the space in the second layer with the securing member using the electrode, whereby a metallurgical bond is formed between the securing member and the third layer; and securing the second layer to the first layer or the third layer, wherein the securing comprises resistance welding the second layer to the first layer or the third layer using the electrode, whereby a metallurgical bond is formed between the second layer and the first layer or the third layer. 19. The method according to clause 18, wherein resistance welding the fastener to the third layer through the space in the second layer comprises deforming the first layer at the first location in space. 20. The method according to clause 19, wherein after deforming the first layer, a fastener head is placed at least partially within a recess formed in the first layer by deforming the first layer. [0052[ A person of mid-level skill will recognize that the items and methods described herein, and the accompanying analysis, are used as examples for the sake of conceptual clarity and that various configuration modifications are contemplated. Therefore, as used herein, the specific examples / modalities presented and the accompanying analysis are intended to be representative of their more general classes. In general, the use of any specific example is intended to be representative of its class, and the omission of specific components, devices, operations / actions, and objects should not be considered restrictive. While this disclosure provides descriptions of various MA / a / ZUZZ / UI While specific aspects are provided to illustrate various aspects of this disclosure and / or its potential applications, it is understood that persons of average skill will come up with variations and modifications. Accordingly, the invention or inventions described herein should be understood to be at least as broad as claimed and not as narrowly defined by the particular illustrative aspects provided herein.

Claims

1. A fastening method, the method being characterized in that it comprises: contacting a fastener with a first layer of an assembly at a first location, the assembly comprising the first layer, a third layer and a second layer positioned intermediate between the first layer and the third layer, wherein the first layer, the third layer and the fastener are electrically conductive, and wherein the second layer defines a space and the first location is in communication with the space; forming an electrical communication between the assembly and the fastener; and fastening the first layer to the third layer through the space in the second layer with the fastener, wherein the fastening comprises resistance welding the fastener to the third layer.

2. The method according to claim 1, characterized in that it further comprises, prior to contact, removing at least a portion of the second layer to form the space, wherein the removal comprises one or more stamping, machining, cutting, grinding, punching and drilling operations.

3. The method according to claim 2, characterized in that it further comprises, prior to contact, placing the second intermediate layer between the first layer and the third layer to provide the assembly.

4. The method according to claim 1, characterized in that the fastener comprises a head and a stem, and wherein contacting the fastener with the first layer at the first location comprises contacting the stem with the first layer at the first location.

5. The method according to claim 4, characterized in that it comprises attaching the first layer to the third layer through the space in the second layer further comprises deforming the first layer at the first location in space in the second layer.

6. The method according to claim 5, characterized in that the fastener head is placed at least partially within a recess formed in the first layer after deforming the first layer.

7. The method according to claim 6, characterized in that after fastening the first layer to the third layer through the space in the second layer with the fastener, the head of the fastener protrudes no more than 1.5 mm beyond a surface of the assembly.

8. The method according to claim 1, characterized in that the space in the second layer comprises a dimension no greater than 50 mm.

9. The method according to claim 1, characterized in that each of the first layer, the third layer and the fastener comprises a metal or a metal alloy, and the second layer comprises one or more of a metal, a metal alloy and a composite material.

10. The method according to claim 1, characterized in that it comprises a yield strength of the first layer that is less than a yield strength of the third layer.

11. The method according to claim 1, characterized in that the first layer and the third layer comprise different materials.

12. The method according to claim 1, characterized in that the second layer and the first layer or the third layer comprise the same material.

13. The method according to claim 12, characterized in that it further comprises resistance welding the second layer to the first or third layer, thereby forming a metallurgical bond.

14. The method according to claim 1, characterized in that resistance welding the fastener to the third layer comprises: applying an electrical potential across the assembly and the fastener, which resistively heats and softens the first location of the first layer; pushing the fastener through the first layer at the first location towards the third layer; and contacting the fastener and the third layer and resistance welding the fastener to the third layer, which forms a metallurgical bond between the fastener and the third layer.

15. The method according to claim 14, characterized in that it comprises applying an electric potential across the assembly and the fastener, and comprising bringing the fastener into contact with an electrode of a resistance welding device.

16. The method according to claim 15, characterized in that it further comprises resistance welding the second layer to the first or third layer using the electrode of the resistance welding device, thereby forming a metallurgical bond between the second layer and the first or third layer.

17. The method according to claim 1, characterized in that it comprises: depositing a welding adhesive onto one or more of the first layer, the second layer, and the third layer; and curing the adhesive after clamping the first layer to the third layer through the gap in the second layer with the clamp.

18. A fastening method, characterized in that it comprises: contacting a fastener with a first layer of an assembly at a first location, the assembly comprising the first layer, a third layer, and a second layer positioned intermediate between the first layer and a third layer, wherein the first layer, the third layer, and the fastener are electrically conductive, wherein the second layer defines a space and the first location is in communication with the space, and wherein a material of the second layer differs from a material of the first layer or a material of the third layer; contacting an electrode of a resistance welding device with the fastener and forming an electrically conductive path between the electrode, the fastener, and the assembly;securing the first layer to the third layer, wherein the securing comprises resistance welding the securing member to the third layer through the space in the second layer with the securing member using the electrode, whereby a metallurgical bond is formed between the securing member and the third layer; and securing the second layer to the first layer or the third layer, wherein the securing comprises resistance welding the second layer to the first layer or the third layer using the electrode, whereby a metallurgical bond is formed between the second layer and the first layer or the third layer.

19. The method according to claim 18, characterized in that resistance welding the fastener to the third layer through the space in the second layer comprises deforming the first layer at the first location in space.

20. The method according to claim 19, characterized in that after deforming the first layer, a fastener head is placed at least partially within a recess formed in the first layer by deforming the first MA / a / ZUZZ / UI Allá layer.

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