Patent Application
20180029168
The present disclosure relates to a laminate of metal sheets including a core layer disposed between and connected to the metal sheets, and specifically, to a laminate including metal sheets of an aluminum material.
A laminate sheet made of metal sheets including a viscoelastic core disposed therebetween is less dense than a monolithic (solid) metal sheet of the same thickness. The monolithic metal sheet may be noisier, e.g., may exhibit less favorable noise-vibration-harshness (NVH) characteristics as compared with the laminate sheet, due to the modulus differences of the materials, where the monolithic metal sheet is more susceptible to vibration and resonance and more sensitive to frequency management than the laminate sheet. Further, structural components formed from sheet material can include complex shapes such as bends, ribs, beads, offsets, depressions, channels, contours and the like, which can be added to improve stiffness and/or bending strength to the structural component. Such complex features can protrude from the sheet, increasing the packaging space required by the structural component and increasing radiated noise through the monolithic component. As such, structural components formed from monolithic metal sheet often require modification by adding damping coatings and/or damping componentry such as damping patches to provide acceptable NVH behavior. Such added treatments, coatings and/or damping componentry add cost and weight to the monolithic component. Accordingly, the total weight of a structural component made of a laminate structure is substantially less than the total weight of a structural component made of a monolithic sheet and subsequently treated with added damping coatings or damping componentry.
Monolithic metal sheet and monolithic structural components formed from monolithic sheet can be joined by welding to other metal components. Welding of laminate sheet and welding of laminate components formed from laminate sheet differs from welding of monolithic sheet, due to the insulating (non-conductive) characteristics of the viscoelastic layer of the laminate sheet which inhibits current flow through the weld zone during welding, and liquefying and/or vaporizing of the viscoelastic layer which can occur during the welding process, where the liquefied and/or vaporized viscoelastic material can contaminate the weld being formed and/or contribute to the formation of porosity in the weld. Porosity and/or contamination in the weld can decrease the durability, fatigue strength and overall integrity of the weld.
As such, it is desirable to provide a laminate sheet material which may be formed into a laminate structural component which, relative to a monolithic structural component formed from a monolithic metal sheet, exhibits relatively lower total weight and relatively better damping characteristics, and is attachable to other components by welding.
A weldable laminate structure and method of forming a welded joint is described. The laminate structure, which includes a viscoelastic adhesive layer between and bonding aluminum sheets, is advantaged by being formable into a structural component which provides desired levels of vibration damping, sound transmission loss, structural separation, etc. at a lower total weight relative to a structural component formed of a monolithic metal sheet, by eliminating the treatments, such as sound dampening coatings or patches, which must be added to the structural component made from monolithic aluminum to achieve the desired NVH performance. A structural component, as that term is used herein, refers to a component formed from sheet material which has a complex shape, e.g., a shape other than flat sheet, and is used in a structural application. The structural component can be formed from the laminate structure, by any forming process suitable for forming monolithic sheet material into a structural component, including, by way of non-limiting example, stamping, extrusion, blanking, bending, etc., such that the better damping performance and total system weight reduction can be achieved by forming the structural component from a laminate structure without requiring significant change to the forming process used to form the structural component formed from monolithic aluminum.
For example, the complex shape of a structural component can be defined by one or more features, such as one or more of a bend, rib, aperture, bead, offset, chamfer, depression, channel, curve, contour, extruded portion, or other feature formed into the laminate structure to define the structural component. As such, the laminate structure described herein can be formed into structural components where there is a particular need for noise dissipation, vibration and/or sound damping, structural separation, thermal insulation and/or acoustic absorption, for example, between spaces or areas separated by the structural component(s) formed of the laminate structure. The term “structural component” is non-limiting, such that a structural component may have nominal or minimal load bearing requirements. In a non-limiting example, the laminate structure described herein is formable into structural components for vehicle applications, such as close-out panels, also known as dash panels or floor pans, which provide structure to the vehicle by separating, respectively, the engine compartment or trunk compartment from the passenger compartment. Other non-limiting examples of vehicle structural components which may be formed from the laminate structure include wheel wells, transmission tunnel covers, cowl plenums, etc.
A laminate structure and method of forming is provided. The laminate structure includes a first metal sheet having a first thickness, a second metal sheet having a second thickness, and an adhesive core having an adhesive thickness. The adhesive core is disposed between and bonded to the first and second metal sheets. The first and second metal sheets are made of an aluminum based material and the adhesive core is made of an adhesive material which may also be described herein as a viscoelastic adhesive material. The viscoelastic adhesive material, in a non-limiting example, can be made of one of a phenolic modified rubber material, an acrylic based material, and a polyester based material.
In one example, the laminate structure is a weldable laminate structure formed by including a plurality of electrically conductive filler particles dispersed in the adhesive material of the core layer. The filler particles are made of a first filler material and a second filler material which is a different material than the first filler material, where at least one the first and second filler materials has a filler electrical resistivity greater than the aluminum electrical resistivity. The plurality of electrically conductive filler particles are dispersed in the adhesive core to define a conduction path by which an electrical current applied to one of the first and second metal sheets is conducted through the adhesive core to the other of the first and second metal sheets to generate a resistive heat which is sufficient to at least partially melt the first and second metal sheets in a weld zone including the conduction path. The percentage weight of the filler particles is in a range of about 12% to 49% of the total weight of the adhesive core. The volume percent of the filler particles is less than about 15% of the total volume of the adhesive core. A method of welding the laminate structure formed with the electrically conductive filler particles is provided.
As used herein “substantially,” “generally,” and other words of degree are relative modifiers intended to indicate permissible variation from the characteristic so modified. It is not intended to be limited to the absolute value or characteristic which it modifies but rather possessing more of the physical or functional characteristic than its opposite, and preferably, approaching or approximating such a physical or functional characteristic. As used herein with respect to any disclosed values or ranges, the term “about” indicates that the stated numerical value allows for slight imprecision, e.g., reasonably close to the value or nearly, such as ±10 percent of the stated values or ranges. If the imprecision provided by the term “about” is not otherwise understood in the art with this ordinary meaning, then “about” as used herein indicates at least variations that may arise from ordinary methods of measuring and using such parameters. In addition, disclosure of ranges includes disclosure of all values and further divided ranges within the entire range.
The above features and advantages, and other features and advantages, of the present teachings are readily apparent from the following detailed description of some of the best modes and other embodiments for carrying out the present teachings, as defined in the appended claims, when taken in connection with the accompanying drawings.
The elements shown in
The laminate structure 100 described herein may be formed into structural components where there is a particular need for enhancing structural reinforcement, vibration and/or sound damping, thermal insulation and/or acoustic absorption, for example, between spaces or areas separated by the structural component(s) formed of the laminate structure 100. The laminate structure 100 described herein, including aluminum sheets 12, 14 and core layer 10, is advantaged by being formable into a structural component which provides desired levels of vibration damping, sound transmission loss, structural separation, etc. at a substantially lower weight relative to a structural component formed of a steel based material. The laminate structure 100 is advantaged by being formable into a structural component which provides significantly improved levels of vibration damping, sound transmission loss, etc. at an equal or lower weight relative to a structural component formed from a monolithic metal sheet, and without requiring added treatments, such as sound dampening coatings or patches, to achieve the desired NVH performance. A structural component, as that term is used herein, refers to a component formed from sheet material which has a complex shape, e.g., a shape other than flat sheet, and is used in a structural application. For example, the complex shape of a structural component can be defined by one or more features, such as one or more of a bend, rib, aperture, bead, offset, chamfer, depression, channel, curve, contour, extruded portion, or other feature formed into the laminate structure to define the structural component. The formed features defining a structural component formed from the laminate structure 100 create discontinuities in the laminate structure 100 which change the modal frequencies of the laminate structure 100. For example, discontinuities created by formed features in a component formed from the laminate structure 100 modify and/or change resonant frequencies of sound waves transmitted through the laminate structure 100, relative to the transmission of sound waves through a monolithic (solid) material. As such, the laminate structure 100 described herein can be formed into structural components where there is a particular need for noise dissipation, vibration and/or sound damping, thermal insulation and/or acoustic absorption, for example, between spaces or areas separated by the structural component(s) formed of the laminate structure 100. The term “structural component” is non-limiting, such that a structural component can include components having formed features which have nominal or minimal load bearing requirements, although it would be understood that formed features such as ribs, channels, beads, or other geometric formed features included in a component formed from the laminate structure 100 can increase the stiffness and/or rigidity of the component. In a non-limiting example, the laminate structure 100 described herein is formable into structural components for vehicle applications, such as close-out panels, also known as dash panels or floor pans, which provide structure to the vehicle by separating, respectively, the engine compartment or trunk compartment from the passenger compartment. Other non-limiting examples of vehicle structural components which may be formed from the laminate structure 100 include wheel wells, transmission tunnel covers, floor pans, cowl plenums, etc. In a non-limiting example, the core layer 10 may be electrically conductive and/or the aluminum sheet 12, 14 may be coated such that the laminate structure 100 can be joined by welding to another metallic component 50 (see
In a preferred example the aluminum based material comprising aluminum sheets 12, 14 is one of a 5xxx and 6xxx series aluminum alloy having elongation greater than about 15%, preferably greater than about 20%, and more preferably having an elongation of at least about 25%, and having an n value of at least 0.1 and an r value of at least 0.8, where the n and r values characterize formability of the aluminum sheet 12, 14. The “n value” as used herein is understood as being the strain hardening exponent obtained by calculating the slope of the true stress and true strain curve of the material, where it is understood that increasing the n value increases the formability of the material. The “r value” as used herein is understood as being the Lankford value, also referred to as the Lankford coefficient, plastic strain ratio, and/or plastic anisotropy factor, and is a measure of the ratio of the true width (or lateral) strain to the true thickness strain in a tensile test of the aluminum sheet 12, 14. The r value indicates the capacity of an aluminum sheet to resist thinning, where it is understood that the higher the r value, the greater the resistance to thinning during deep drawing. By way of example, a 5xxx or 6xxx series aluminum alloy can be used for aluminum sheets 12, 14 to provide high elongation and a heat stable structure such that the base substrates, e.g., the aluminum sheets 12, 14, provide strength and stiffness while being formable, for example, by stamping, extrusion, deep drawing, etc. The aluminum material forming the aluminum sheets 12, 14 may be ¼ hard or lower, such that the aluminum sheets 12, 14 are readily formable. For example, the aluminum sheets 12, 14 may be provided in an annealed temper condition also known as an “OT” temper, or in a strain hardened tempered ¼ hard condition also known as an “H2” temper. In one example, a laminate structure 100 usable for forming automotive components such as dash panels is formed of aluminum sheets 12, 14 of a 6xxx series aluminum alloy provided with an OT temper, such that the laminate structure 100 is readily formable by pressing and/or stamping into complex shapes such as dash panels, and is heat treatable, for example, during paint baking of the dash panels and/or vehicle including the dash panels formed from the laminate structure 100. The example of a 5xxx or 6xxx series aluminum alloy material used for forming aluminum sheets 12, 14 is non-limiting, and it would be understood that other aluminum alloys may be used to form aluminum sheets 12, 14.
By way of non-limiting example and referring to
The core layer 10 is disposed between the aluminum sheets 12, 14 such that the core layer 10 spans substantially the entirety of (i.e., is coextensive with) the metal layer 12 and the metal layer 14. The laminate structure 100 is formed by laminating the metal sheets 12, 14 with the core layer 10 disposed therebetween such that the core layer 10 adheres (i.e., rigidly attaches) the two aluminum sheets 12, 14 together. The core layer 10 includes an adhesive core 16, which substantially defines and/or provides the NVH (noise, vibration, harshness) and damping performance characteristics of the laminate structure 100. The core layer 10 and/or the adhesive core 16 has sufficient adhesive properties to attach the two aluminum sheets 12, 14 to each other, and has viscoelastic properties such that it dissipates vibrational energy by converting the vibrational energy into thermal energy through internal shearing of the adhesive material 38.
Referring again to
The adhesive material 38 forming the adhesive core 16 may be applied to one of the aluminum sheets 12, 14 in a single layer prior to laminating the aluminum sheets 12, 14 together with the adhesive core 16 therebetween to form the laminate structure 100. In another example, the adhesive material 38 forming the adhesive core 16 may be applied in two adhesive layers 18, 20, as shown in
The thickness of each of the two adhesive layers 18, 20 is controlled to provide the desired total dry film thickness T3 of the adhesive core 16 in the finished laminate structure 100. By way of non-limiting example, the overall thickness of the laminate structure 100, exclusive of exterior layers 26, 28 and isolation layers 34, may be in the range of about 0.813 mm to 4.76 mm. For example, a laminate structure 100 may include aluminum sheets 12, 14 each having a thickness T1, T2 of 0.4 mm and an adhesive core having a thickness T3 of 0.013 mm for a total thickness (T1+T2+T3) of 0.813 mm and an aluminum to adhesive thickness ratio of 61.5, where the aluminum to adhesive thickness ratio is calculated as (T1+T2)/T3. In another example, a laminate structure 100 may include aluminum sheets 12, 14 each having a thickness T1, T2 of 2.0 mm and an adhesive core having a thickness T3 of 0.076 mm for a total thickness of 4.076 mm and an aluminum to adhesive thickness ratio of 52.6. In a preferred example, the overall thickness of the laminate structure 100 may be in the range of about 1.45 mm to 1.66 mm. For example, a laminate structure 100 in the preferred thickness range may include aluminum sheets 12, 14 each having a thickness T1, T2 of 0.6 mm and an adhesive core 16 having a thickness T3 of 0.025 mm for a total thickness of 0.1.45 mm. In another preferred example, a laminate structure 100 may include aluminum sheets 12, 14 each having a thickness T1, T2 of 0.8 mm and an adhesive core having a thickness T3 of 0.06 mm for a total thickness of 1.66 mm. In a preferred example, the ratio of the combined thickness (T1+T2) of the aluminum sheets 12, 14 to the thickness T3 of the adhesive core 16 is within the range of about 25 to 50, where it would be understood that the thickness T1, T2 of the aluminum sheets 12, 14 substantially contributes the tensile strength and rigidity to the laminate structure 100, and the thickness T3 of the adhesive core 16 substantially contributes to the damping characteristics of the laminate structure 100, and where the thickness ratio influences the CLF behavior of the laminate structure 100. The optimal thickness for efficient vibration dissipation can be calculated for every metal gage used. By way of example, the laminate structure 100 may be characterized by an adhesive thickness ratio in the range of about 8:1 to 50:1. The laminate structure 100 having an aluminum to adhesive thickness ratio ((T1+T2)/T3) of 8:1 or more is characterized by a density substantially similar to that of monolithic (solid) aluminum, which has a density of 2.7 gm/cc. In a preferred example, a laminate structure 100 having an aluminum to adhesive thickness ratio ((T1+T2)/T3) of 25:1 has a density of at least 2.56 gm/cc, such that the density of the laminate structure 100 is at least about 95% that of monolithic aluminum, contributing to the tensile properties and rigidity of the laminate structure 100. In a preferred example, the laminate structure 100 has a density of at least 2.64 gm/cc.
The adhesive material 38 of the adhesive layers 18, 20 may be, in a non-limiting example, one of a polyester based material which may be a cross-linking polyester, an acrylic based material which may optionally include a cross-linking agent to provide relatively higher resistance to chemical attack, and a phenolic modified rubber. In one example, the adhesive core 16 formed from the phenolic modified rubber material may be characterized by a matrix structure including rubber dispersed in a phenolic matrix such that bond strength of the laminate structure 100 is substantially defined by, e.g., resultant from, the bonding of the phenolic to the aluminum sheets 12, 14 and the bonding of the phenolic to the dispersed rubber particles. The adhesive material 38 may be applied to the aluminum sheet 12, 14 by any suitable technique, including, for example, spraying, hot melt and/or rolling techniques by which the adhesive material 38 is applied to the aluminum sheet 12, 14, as a solvent based adhesive material, to provide full coverage of the aluminum sheet 12, 14 at the desired thickness prior to laminating the aluminum sheets 12, 14 together. In another example, the adhesive material 38 may be provided as a dry adhesive film and applied to one or both of the aluminum sheets 12, 14 prior to laminating. The dry adhesive film can be applied, for example, in a continuous process where the dry adhesive film is interleaved between the aluminum sheets 12, 14 prior to laminating. The adhesive material 38 is heated and/or cured during the laminating process forming the laminate structure 100 by a means suitable to the type of the adhesive material 38 being applied, which may include one or a combination of exposing the adhesive material 38 to elevated temperatures, for example, using flame bars, incinerator ovens, hot air ovens, etc., and/or hot melt, infrared, and ultraviolet systems as understood by those knowledgeable in the field of laminating. The examples are non-limiting, and it would be understood that other forms of adhesive materials 38 such as dry powder or web forms, application methods and curing processes may be used within the scope of forming the laminate structure 100 including the aluminum sheets 12, 14 and the core layer 10 described herein.
The adhesive material 38 forming the core layer 10 and/or the adhesive core 16 is characterized by an elongation which is substantially greater than the elongation of the aluminum material comprising the aluminum sheets 12, 14, such that during deformation of the laminate structure 100, for example, during stamping, extrusion, and/or bending of the laminate structure 100 to form a component therefrom, the core layer 10 remains in an elastic range and does not separate from the edges of and/or between the aluminum sheets 12, 14 of the laminate structure 100, where it would be understood that separation of the adhesive core 16 from the aluminum sheets 12, 14 would affect the damping characteristics of the laminate structure 100 in the localized area where the separation occurred. By way of non-limiting example, the core layer 10 and/or the adhesive core 16 is characterized by a minimum elongation of about 150%. In a preferred example, the core layer 10 and/or the adhesive core 16 is characterized by a minimum elongation of about 300%, and in a more preferred example, an elongation in the range of about 300% to 400%. Preferably, a minimum elongation ratio of about ten (10) is maintained for the laminate structure 100, where the elongation ratio is expressed as the elongation of the core layer 16 relative to (divided by) the elongation of the thinner of the aluminum sheets 12, 14, to prevent fracture of the core layer 16 and maintain the damping capacity of the laminate structure 100. In a more preferred example, the laminate structure 100 is characterized by a minimum elongation ratio of about twenty (20). In a most preferred example, the laminate structure 100 is characterized by a minimum elongation ratio in the range of about twenty (20) to thirty (30). In one example, the laminate structure 100 includes 5XXX (series aluminum sheets 12, 14 each having a thickness T1, T2 of 0.80 mm and an elongation in the range of about 18% to 22% and a modified rubber adhesive core 16 having a nominal thickness T3 of 0.025 mm and an elongation of about 300% such that the example laminate structure 100 is characterized by an elongation ratio of about 13.6 to 16.7.
In a preferred example for forming the core layer 16 and laminate structure 100, an adhesive material 38 is selected, applied to one or both of the aluminum sheets 12, 14, cured and laminated to provide a laminate structure 100 which is characterized by an adhesive strength as measured by T-peel of at least ten pounds-force/inch (10 lbf/in or approximately 1.75 Newtons/millimeter (N/mm)) using a T-peel strength test performed for example, in compliance with ASTM D1876 at a 10 inch/minute pull rate, a lap shear strength of at least two mega Pascal (2 MPa) a lap shear strength test performed for example, in compliance with ASTM D1002, a yield strength of 100-120 kilo-pounds per square inch (KSI) with an ultimate tensile strength of 200-250 KSI where plastic failure of at least one of the aluminum sheets 12, 14 occurs prior to plastic failure of the adhesive core 16. In a most preferred example, the laminate structure 100 is characterized by an adhesive strength as measured by T-peel of at least fifteen foot-pounds/inch (15 lbf/in or approximately 2.63 N/mm).
In a preferred example, the laminated structure 100 retains a minimum of 80% of the original bond strength, as indicated by lap shear strength and T-peel strength, after heat cycle aging, after thermal cycle (cold shock or cold/hot thermal cycling testing, for example, between −30 degrees C. and +105 degrees C.) testing, and after cyclic corrosion testing (for example, SAE J2334 testing), where the criteria for each of these is application specific for the intended use of the laminate structure 100 or a component formed therefrom. In one example, the laminate structure 100 is characterized by retaining greater than 80% of the original bond strength after being subjected to heat cycle aging at 205 degrees Celsius for 40 minutes, to provide a laminate structure 100 which can be subjected during a coating process cycle such as electro-coating (electrostatic coating or E-coat) cycle or painting cycle to a baking operation where the laminate structure 100 is heated in a paint or e-coat oven in excess of 100 degrees Celsius and up to 205 degrees Celsius, without degradation of the laminate structure 100 or component formed therefrom. For example, such a laminate structure 100 is suitable for forming into an automotive component such as a dash panel, etc., which may be e-coated or painted. In the preferred example, the laminate structure 100 is able to withstand a 90 degree 1 T radius bend at 0.75 inch flange length without degradation, where T is the thickness of the laminate structure 100 expressed in inches, where in the present example the laminate structure 100 includes aluminum sheets 12, 14 made of 5xxx series aluminum material and an adhesive core 16 made of modified rubber, the laminate structure 100 having a total thickness of approximately 0.072 inches. In a preferred example, a laminate structure 100 includes aluminum sheets 12, 14 made of 5xxx series aluminum material with an “O” temper to provide high elongation with relatively low tensile strength such that minimal springback occurs during and after forming of a component from the laminate structure 100, e.g., such that the laminate structure 100 exhibits forming characteristics similar to a deep draw grade ferrous material.
The laminate structure 100 exhibits a bending rigidity at room temperature (approximately 23 degrees Celsius) which is at least 35% that of a solid (monolithic) aluminum sheet having a thickness equal to the combined thickness (T1+T2) of the aluminum sheets 10, 12. In a preferred example, the laminate structure 100 exhibits a bending rigidity at room temperature of 50% or more relative to a monolithic aluminum sheet having a thickness equal to the combined thickness (T1+T2) of the aluminum sheets 10, 12. In a more preferred example, the laminate structure 100 exhibits a minimum bending rigidity at room temperature of about 60% to 75% of that of a monolithic aluminum sheet having a thickness equal to the combined thickness (T1+T2) of the aluminum sheets 10, 12.
As shown in
The aluminum sheet 12, 14 may be prepared, e.g., pretreated, prior to applying the intermediate layer 22, 24 by cleaning the aluminum sheet 12, 14 with a deoxidation cleaner such as an alkaline cleaner or an acidic cleaner to remove soil, oil, grease, etc. from the surface of the aluminum sheet 12,14 and to remove any aluminum oxide product from the surface of the aluminum sheet 12, 14, to prepare the surface of the aluminum sheet 12, 14 to receive the intermediate layer 22, 24. As such, the deoxidation cleaner creates a “fresh” aluminum surface which, if not subsequently treated, e.g., coated, within a period of time, will reoxidize. As such, the deoxidation cleaner removes the oxide layer from surface of the aluminum sheet 12, 14 to temporarily increase bonding receptivity of the aluminum sheet, for example, to one of the layers 22, 24, 24, 32 described further herein. In a non-limiting example, the aluminum sheet 12, 14 may be cleaned and/or pretreated applying the cleaning solution using, for example, immersion cleaning, spray cleaning, rolling on the cleaning solution, or using other suitable chemical cleaning means to apply the deoxidation cleaner. In another example, the aluminum sheet 12, 14 may be mechanically cleaned to deoxidize, e.g., remove the oxide layer from, the surfaces of the aluminum sheet 12, 14.
In one example, the intermediate coating 22, 24 may be applied at a coating weight thickness (CWT) in the range of about 2.0 to 10.0 milligram/square meter (mg/m2) by spraying the intermediate coating 22, 24 in solution form onto the aluminum sheets 12, 14 or immersing the aluminum sheets 12, 14 in the coating solution. In one example, the intermediate coating 22, 24 is applied as a solution containing titanium and zirconium which passivates the aluminum surface of the aluminum sheet 12, 14, and prevents activation of the aluminum surface over time. In another example, the intermediate coating 22, 24 is applied as a solution containing tri-chromium oxide. The coating solution may also be applied to the exterior surfaces, e.g., the outwardly facing surfaces, of the aluminum sheets 12, 14 to form exterior coating layers 28, 26, as shown in
As shown in
In one example, the laminate structure 100 may include at least one of the auxiliary layer 30, 32 which is a corrosion prevention layer to prevent contaminant ingression at the bonded interface between the adhesive core 16 and the adjacent aluminum sheet 12, 14, for example, by preventing contaminant ingression at an exposed edge of the laminate structure 100. In another example, the laminate structure 100 may include at least one auxiliary layer 30, 32 configured as a thermal coating to modify the thermal emissivity and/or thermal conductivity of the laminate structure 100. For example, at least one auxiliary layer 30, 32 may be made of a heat dissipating material to dissipate heat away from the adhesive core 16, or may be made of a heat absorptive material to absorb heat into the laminate structure 100. In another example, the laminate structure 100 may include at least one auxiliary layer 30, 32 configured as an electrically conductive layer to modify the electrical conductivity of the laminate structure 100. For example, the laminate structure 100 shown in
Referring to
In one example, at least one of the exterior layers 26, 28 may be configured as an isolation layer 34, as shown in
By way of non-limiting example, a method of forming the laminate structure 100 includes presenting the various layers required to form the laminate structure 100 in the required sequence to a laminating process which includes applying a laminating pressure to the sequenced layers and curing the layered structure such that the layers are bonded together to form the laminate structure 100. By way of non-limiting and illustrative example and referring to
Still referring to the illustrative example shown in
Following the lamination process, e.g., after laminating and curing the sequenced layers forming the laminate structure 100, the laminate structure 100 may be subjected to additional treatments, including, as previously described herein, the application of one or more of the exterior layers 26, 28, 34. The laminate structure 100 may be used to form components therefrom. For example, the laminate structure 100 may be cut, stamped, pressed, bent, extruded, punched, drilled, etc. to form a component, where the component may define one or a combination of one or more bends, fillets, chamfers, shoulders, openings, holes, slots, ribs, flanges, hems, etc. By way of non-limiting example, the laminate structure 100 may be used to form a variety of structural components which may be used in vehicles, such as a dash panel, package tray, panel shelf, seat panel, cowl panel, instrument panel frame, floor panel, tunnel panel, wheel well, back-up panel, trunk panel, etc. The examples are non-limiting, and it would be understood that various components which may be structural or non-structural components, may be formed using the laminate structure 100 described herein.
Referring to
In the example shown in
Referring to
In the illustrative example, the metal component 50 may be, for example, a monolithic component made of a metal such as aluminum or other metal weldable to the laminate structure 100. In another example, the metal component 50 may be a laminate structure such as a laminate structure 100 described herein. For simplicity of illustration, the example illustrated in
In the illustrative examples described herein, except for the first example, the electrically conductive filler particles 36 are composed of at least two filler materials, illustratively shown in
The second criteria for configuration of the filler particles 36 is alloying compatibility with the aluminum of the aluminum sheets 12, 14 during weld formation, e.g., the filler particles 36 should be configured and dispersed in the adhesive core 16 at an additive level which will, when combined with aluminum from the aluminum sheets 12, 14, form an acceptable weld. The filler particles 36 may be provided at an additive level which is controlled to provide, increase, and/or enhance characteristics of the weld which are favorable to formation of an acceptable weld. For example, one of the filler materials 54, 56, 58 may be copper, manganese or magnesium, included at an additive level which enhances one or more of weld ductility, strength, and/or corrosion resistance.
One or more of the filler materials 54, 56, 58 forming the filler particles 36 may be provided at an additive level which is controlled at a balanced level to provide a beneficial effect, such as increasing resistivity of the filler particle 36, while preventing a detrimental effect, such as an alloying incompatibility. For example, one of the filler materials 54, 56, 58 may be iron or nickel, included at a sufficient additive level to increase resistivity however controlled at a sufficiently low additive level to prevent the formation of intermetallic compounds in the resulting weld.
The filler particles 36 can include two or more filler materials 54, 56, 58 provided in various configurations to satisfy the criteria described above. By way of non-limiting example, a filler particle 36 may be provided as a compound formed of the two or more filler materials 54, 56, 58, a mixture, such as a powder mixture, of two or more filler materials 54, 56, 58, coated particles where the particle may be formed of a first filler material 54 and coated with a second filler material 56. The filler particles 36 may be provided as a mixture of a first filler particle made of one or more of the filler materials 54, 56, 58, a second filler particle made of one or more of the filler materials 54, 56, 58 where at least one of the composition, configuration, and/or additive level of the second filler particle is different from the composition, configuration and/or additive level of the first filler particle. In this example, the mixture may include a third, fourth, etc filler particle of a different composition than each of the first and second filler particles.
A third criteria is the volume of filler particles 36 in the adhesive core 16. As the volume of filler particles 36 increases in the adhesive core 16, the bond strength may decrease proportionally. In one example, the criteria for the volume of filler particles 36 is to limit the volume of filler particles 36 in the adhesive core 16 to a level such that the bond strength of the laminate structure 100 including the filler particles 36 is at least 90% of the bond strength of the laminate structure 100 formed without the filler particles 36. The volume of filler particles 36 in the core layer 10 can be expressed as a volume percentage and/or as a corresponding weight percentage based on the configuration and density of the filler particles 36. In one example, the volume of electrically conductive filler particles 36 is preferably less than 18% of the total volume of the core layer 10 and less than 50% of the total weight of the core layer 10. In a more preferred example, volume of electrically conductive filler particles 36 is preferably less than 10% of the total volume of the core layer 10 and less than 30% of the total weight of the core layer 10.
Example 1 is a laminate structure 100 including a core layer 10 including filler particles 36 made of aluminum material containing at least 99.8% aluminum (Al), such that the material chemistry and the electric potential of the filler particles 36 are substantially similar to that of the aluminum sheets 12, 14. The aluminum filler particles 36 are distributed in the adhesive material 36 at an additive level expressed as a percentage weight of the adhesive core 16 in the range of about 5% to 20%, and preferably, at a percentage weight in the range of about 5% to 10%. In this example, the laminate structure 100 having a total thickness T (T1+T2+T3) as shown in
Example 2 is a laminate structure 100 including a core layer 10 including filler particles 36 made of a first filler material 54 which is aluminum (Al) and a second filler material 56 which is zinc (Zn). The filler particles 36 are configured as aluminum particles which are coated with zinc using a zincating process. During the zincating process, the aluminum particles are deoxidized prior to coating with the zinc, such that aluminum oxide is not present in the filler particles 36. The aluminum and the zinc are electrically conductive and zinc has a relatively higher resistivity than aluminum, such that the filler particles 36 made of zincated (zinc coated) aluminum particles provide an electrically conductive path through the core layer 10, which has sufficiently high resistivity to generate heat when electrical current is passed through the laminate structure 100 during a welding operation. The zincated aluminum filler particles 36 are distributed in the adhesive material 36 at an additive level expressed as a percentage weight of the adhesive core 16 in the range of about 5% to 37.5% of the total weight of the adhesive core 16, and preferably, at a percentage weight in the range of about 15% to 25% of the total weight of the adhesive core 16. The volume of zincated aluminum filler particles 36 distributed in the core layer 10 is within the range of about 6% to 15% of the total volume of the core layer 10, and preferably within the range of about 6% to 10% of the total volume of the core layer 10. In this example, the laminate structure 100 having a total thickness T (T1+T2+T3 as shown in
Example 3 is a laminate structure 100 including a core layer 10 including filler particles 36 made of a first filler material 54 which is iron (Fe) and a second filler material 56 which is phosphorus (P). The filler particles 36 are configured as a compound form of iron phosphides (FeP, Fe2P) provided as a powder having a particle size of in the range of about 5 micron to 125 micron, with a median particle size of about 25 micron. The iron is electrically conductive and has a relatively higher resistivity than aluminum, such that the filler particles 36 made of the iron phosphorus compound provide an electrically conductive path through the core layer 10, which has sufficiently high resistivity to generate heat when electrical current is passed through the laminate structure 100 during a welding operation. Of significance, both iron and phosphorus have very low solubility in aluminum in the solid state (˜0.04% for iron and <0.01% for phosphorus), such that both iron and phosphorus are considered an impurity in aluminum. Unexpectedly, when the additive level of the filler particles 36, e.g., the additive level of the iron and phosphorus filler materials in combination, is controlled for alloying compatibility at a percentage weight in the range of about 12% to 49% of the adhesive core 16, and preferably, at a percentage weight in the range of about 20% to 30%, the laminate structure 100 is weldable to a solid (monolithic) aluminum component 50 to form an acceptable weld nugget. Surprisingly, the weld nugget is formed without propagation of iron phosphorus out of the weld in a sufficient quantity to cause adverse effects to the weld nugget, suggesting the iron and phosphorus at this additive level remains in solution in the weld nugget thus formed. In this example, the laminate structure 100 having a total thickness T (T1+T2+T3 as shown in
Example 4 is a laminate structure 100 including a core layer 10 including filler particles 36 made of a first filler material 54 which is zinc (Zn) and a second filler material 56 configured as a plurality of hollow carrier objects. The filler particles 36 are provided as the carrier objects coated with zinc. The carrier objects in this example are hollow glass spheres. The zinc is electrically conductive and has a relatively higher resistivity than aluminum, such that the filler particles 36 made of the zinc coated glass spheres provide an electrically conductive path through the core layer 10, which has sufficiently high resistivity to generate heat when electrical current is passed through the laminate structure 100 during a welding operation. The additive level of zinc coated glass spheres (filler particles 36) is controlled for alloying compatibility at a percentage weight in the range of about 8% to 30% of the adhesive core 16, and preferably, at a percentage weight in the range of about 10% to 20%, and the laminate structure 100 is weldable to a solid (monolithic) aluminum component 50 to form an acceptable weld nugget. In this example, the laminate structure 100 having a total thickness T (T1+T2+T3 as shown in
Example 5 is prepared using the same method as Example 4, except the first filler material 54 is a silver (Ag) coating applied to the hollow glass spheres forming the second filler material 56, to provide filler particles 36 configured as silver coated glass spheres. An acceptable weld nugget measuring between 3.5 mm and 5 mm, using an alternating current (AC) resistance welder is formed. No shunting of current between the outer layers 12, 14 of the laminate structure 10 is observed.
Example 6 is prepared using the same method as Example 4, except the first filler material 54 is a nickel (Ni) coating applied to the hollow glass spheres forming the second filler material 56, to provide filler particles 36 configured as nickel coated glass spheres. An acceptable weld nugget measuring between 3.5 mm and 5 mm, using an alternating current (AC) resistance welder is formed. No shunting of current between the outer layers 12, 14 of the laminate structure 10 is observed.
Example 7 is a laminate structure 100 including a core layer 10 including filler particles 36 made of a first filler material 54 which is magnesium (Mg) and a second filler material 56 which is magnesium oxide (MgO). The filler particles 36 are configured as a mixture of magnesium particles and magnesium oxide particles. The magnesium is electrically conductive and has a relatively higher resistivity than aluminum, and the magnesium oxide has a high resistivity such that the filler particles 36 made of the mixture of magnesium particles and magnesium oxide particles provide an electrically conductive path through the core layer 10 which has sufficiently high resistivity to generate heat when electrical current is passed through the laminate structure 100 during a welding operation. Magnesium has good alloying compatibility with aluminum, with excellent weldability and is not prone to hot-cracking. In this example, the laminate structure 100 having a total thickness T (T1+T2+T3 as shown in
Example 8 is prepared using the same method as Example 7, except the second filler material 56 is manganese dioxide (MnO2). The filler particles 36 are configured as a mixture of magnesium particles and manganese dioxide particles. Manganese dioxide has a high resistivity such that the filler particles 36 made of the mixture of magnesium particles and manganese dioxide particles provide an electrically conductive path through the core layer 10 which has sufficiently high resistivity to generate heat when electrical current is passed through the laminate structure 100 during a welding operation. Manganese has good alloying compatibility with aluminum, with good weldability, providing good ductility and improved corrosion properties to the weld. An acceptable weld nugget which is absent of porosity and crack free is formed using this Example.
Example 9 is a laminate structure 100 including a core layer 10 including filler particles 36 made of mixture of a first filler material 54 which is manganese dioxide (MnO2), a second filler material 56 which is magnesium (Mg), and a third filler material 58 which is aluminum (Al). The filler particles 36 are mixed to form a powder. The magnesium and aluminum have good electrical conductivity. The magnesium and the manganese dioxide have relatively higher resistivity than aluminum, such that the filler particles 36 made of the mixture of manganese dioxide, magnesium and aluminum provide an electrically conductive path through the core layer 10, which has sufficiently high resistivity to generate heat when electrical current is passed through the laminate structure 100 during a welding operation. As described for Examples 6 and 7, both magnesium and manganese have good alloying compatibility with aluminum. The additive level of filler particles 36, e.g., the additive level of the mixture of filler materials 54, 56, 58 is at a percentage weight in the range of about 12% to 49% of the adhesive core 16, and preferably, at a percentage weight in the range of about 20% to 30%, and the laminate structure 100 is weldable to a solid (monolithic) aluminum component 50 to form an acceptable weld nugget. In this example, the laminate structure 100 having a total thickness T (T1+T2+T3 as shown in
Example 10 is prepared using the same method as Example 9, except the second filler material 56 is silicon (Si), which has relatively higher resistivity than aluminum, such that the filler particles 36 made of the mixture of manganese dioxide, silicon and aluminum provide an electrically conductive path through the core layer 10, which has sufficiently high resistivity to generate heat when electrical current is passed through the laminate structure 100 during a welding operation. A weld nugget measuring between 3.5 mm and 5 mm was formed, and no shunting of current between the outer layers 12, 14 of the laminate structure 10 is observed.
Example 11 is prepared using the same method as Example 9, except the third filler material 58 is zinc, which has relatively higher resistivity than aluminum and good alloying compatibility with aluminum, such that the filler particles 36 made of the mixture of manganese dioxide, silicon and zinc provide an electrically conductive path through the core layer 10, which has sufficiently high resistivity to generate heat when electrical current is passed through the laminate structure 100 during a welding operation. A weld nugget measuring between 3.5 mm and 5 mm was formed, and no shunting of current between the outer layers 12, 14 of the laminate structure 100 is observed.
The illustrative examples provided by the description herein and the related figures are non-limiting, and it would be understood that a plurality of alternative configurations of the layers of the laminate structure 100 exist within the scope of the description incorporating various combinations of the metal sheets 12, 14, configurations of the core layer 10, various configurations of the adhesive core 16, various configurations of the filler particles 36, various combinations and/or configurations of the filler materials 54, 56, 58 comprising the filler particles 36, and various combinations and/or configurations of one or more of intermediate layers 22, 24, auxiliary layers 30, 32, exterior layers 26, 28, separating layers 34, and/or filler particles 36 to provide a laminate structure 100 characterized by a combination of properties and/or features as required by the specified application and/or use of the laminate structure 100 and/or a component formed therefrom. The Examples provided herein are illustrative and the teachings provided by the Examples envision that similar results are expected when any of the values provided in the examples are varied within the ranges provided, and envision that similar results are expected by substitution of materials having substantially similar properties, for example, substantially similar electrical properties such as resistivity and conductivity, as those noted above. By way of illustration, referring to Example 7, it is envisioned that similar results as to weldability of the laminate 100 can be achieved using filler particles 36 comprised of a first conductive metal 54 which shows good alloying compatibility with aluminum, such as one or more of a group consisting of manganese, aluminum (deoxidized), zinc, silicon and copper, and a second conductive metal 56 which is the oxidized counterpart of the metal 54. For example, a laminate structure 100 including particles 36 comprising a mixture of zinc and zinc oxide is envisioned to be weldable to form a weld nugget without shunting. In another illustrative example, referring to Example 2, it is envisioned that the aluminum particles could be coated with another conductive material other than zinc, to provide filler particles 36 to form a laminate structure which is weldable. In yet another illustrative example, referring to Example 4, it is envisioned that the hollow carrier objects may be provided in a shape other than a sphere, e.g., for example, could be provided in a non-spherical ovoid shape, as a cylinder, rod, ellipsoid, etc. or other shape capable of current bridging the first and second aluminum layers 12, 14 and/or nesting in contact to provide a conductive path between the first and second aluminum layers 12, 14 when coated with a conductive material. Referring again to Example 4, it is envisioned that the hollow carrier objects can be formed of materials other than glass, for example, ceramic based materials, and/or that the conductive material coating the glass sphere may be another material which satisfies the criteria for electrical conductivity and resistance and alloying compatibility, such as nickel.
The combination of properties and/or features for which a laminate structure 100 is configured includes a combination of one or more of NVH properties, damping, elongation, tensile strength, shear strength, formability, peel strength, corrosion prevention, thermal properties, electrical conductivity, and/or weldability. The example configurations of laminate structures 100 shown in
The detailed description and the drawings or figures are supportive and descriptive of the present teachings, but the scope of the present teachings is defined solely by the claims. While some of the best modes and other embodiments for carrying out the present teachings have been described in detail, various alternative designs and embodiments exist for practicing the present teachings defined in the appended claims.
This Application claims the benefit of International Patent Application PCT/US2016/029974, filed on Apr. 29, 2016, and of International Patent Application PCT/US2015/028801, filed on May 1, 2015, which are hereby incorporated by reference in their entirety.
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/US2016/029974 | Apr 2016 | US |
| Child | 15729095 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/US2015/028801 | May 2015 | US |
| Child | PCT/US2016/029974 | US |
