| Hybrid resistance/ultrasonic welding system and method -> Monitor Keywords |
|
|
  Hybrid resistance/ultrasonic welding system and methodUSPTO Application #: 20080041922Title: Hybrid resistance/ultrasonic welding system and method Abstract: A hybrid resistance heating/ultrasonic welding method is used to join substrates. The resistance heating sufficiently softens or melts the substrates at an interface, and an ultrasonic wave is used solid state bond the substrates at the interface. The hybrid method can be used for both spot welding as well as continuous welding. (end of abstract) Agent: Daimlerchrysler Intellectual Capital Corporation Cims 483-02-19 - Auburn Hills, MI, US Inventors: Mariana G Forrest, Feng Lu, Stephen D. Logan USPTO Applicaton #: 20080041922 - Class: 2281411 (USPTO) The Patent Description & Claims data below is from USPTO Patent Application 20080041922. Brief Patent Description - Full Patent Description - Patent Application Claims
FIELD OF THE INVENTION [0001]The present disclosure relates to a hybrid resistance/ultrasonic welding system and method. BACKGROUND OF THE INVENTION [0002]The statements in this section merely provide background information related to the present disclosure and may not constitute prior art. [0003]As automotive technology has advanced, weight reduction requirements have increased. In pursuit of these lower weight requirements, investigation into materials for use in automotive components that are lighter in weight and higher in strength has also increased. Materials such as aluminum, magnesium, and advanced high strength steels, therefore, are beginning to become more common in automotive applications. The use of these materials, however, has caused problems in that these materials are generally difficult to join together by welding. [0004]For example, a material known as twinning induced plasticity (TWIP) steel shows dramatic improvement in both strength and ductility. TWIP steel, however, contains carbon and manganese in a content that results in a carbon equivalent (CE) value that ranges from 3.33 to 4.7. The CE value is commonly used to evaluate the weldability of steel. When this value exceeds 0.5, the material is considered difficult to weld. Because the CE value of TWIP steel is 6.7 to 9.4 times larger than more commonly used steel sheets that are presently used in automotive applications, the weldability of TWIP is difficult. Accordingly, there is a need for an improved welding technology that makes it possible to join the lightweight and increased strength materials that are now considered for use in automotive applications. SUMMARY OF THE INVENTION [0005]To satisfy the above need, the present teachings provide a spot welding method that includes providing a pair of substrates, and applying an electric current to the substrates to soften the substrates at an interface between the substrates. After the substrates are softened, an ultrasonic wave is applied to the substrates to solid-state bond the substrates at the interface. [0006]The present teachings also provide a continuous welding method that includes feeding a pair of substrates through a first set of rollers. The first set of rollers are adapted to apply an electric current through the substrates at an interface between the substrates. The pair of substrates are also fed through a second set of rollers. The second set of rollers are adapted to apply an ultrasonic wave through the substrates at the interface. The substrates are subsequently joined at the interface by applying the electric current and the ultrasonic wave to the substrates. [0007]Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention. BRIEF DESCRIPTION OF THE DRAWINGS [0008]The drawings disclosed herein are for illustration purposes only and they are not intended to limit the scope of the present disclosure in any way. [0009]FIGS. 1A and 1B are schematic cross-sectional representations of a spot welding method according to the present teachings; [0010]FIGS. 2A and 2B are schematic cross-sectional representations of a seam welding method according to the present teachings; [0011]FIGS. 3A and 3B are schematic cross-sectional representations of another spot welding method according to the present teachings; and [0012]FIGS. 4A and 4B are a schematic cross-section representations of an electrode/sonotrode used in accordance with the present teachings. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [0013]The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses. [0014]Referring to FIG. 1, a first embodiment of the present teachings will now be described. In FIG. 1, a pair of substrates 10 and 12 are being welded together according to the method of the present teachings. The substrates 10 and 12 are formed of advanced high strength steels (AHSS), and particularly twinning induced plasticity steel (TWIP). Although the present teachings are advantageous in welding AHSS such as TWIP steel, it should be understood that other materials that may be welding in this manner include substrates formed from steel, stainless steel, aluminum (Al), magnesium (Mg), tungsten (W), titanium (Ti), cobalt (Co), silver (Ag), copper (Cu), brass, bronze, Fe-Austenite, nickel (Ni), platinum (Pt), platinum iridium (Pt--Ir), chromium (Cr), iridium (Ir), Fe-Martensite, molybdenum (Mo), niobium (Nb), tantalum (Ta), and other difficult-to-weld alloys such as Inconel, Monel, and nickel-based (Ni) superalloys. Substrates formed of dissimilar materials (i.e., one substrate formed of a first material and another substrate formed of a second and different material) may also be joined together using the present teachings. [0015]Additionally, metal substrates that include a coating such as zinc (Zn) or an oxide may also be used. In the present embodiment shown in FIG. 1, the substrates 10 and 12 are coated with Zn. The coating 11 and 13 formed on the substrates 10 and 12, respectively, prevents rust and other materials from reducing the useful life of the substrates 10 and 12. To join the substrates 10 an 12 together, a pair of electrodes 14 and 16 pass an electric current 18 through the substrates 10 and 12. [0016]The electrodes 14 and 16 press the substrates 10 and 12 with enough force to sufficiently ensure that no gap is between the substrates 10 and 12 at an interface 19 where the substrates 10 and 12 are to be joined together. By having no gap at the interface 19 between the substrates 10 and 12, there is sufficient contact between the substrates 10 and 12 to ensure electrical conductivity between the substrates 10 and 12. To press the substrates 10 and 12 together with the electrodes 14 and 16, the electrodes 14 and 16 may be coupled to a device (not shown) such as a pneumatic or hydraulic device that is sufficient to ensure face-to-face contact between the substrates 10 and 12 at the interface 19. In this regard, the device should be capable of pressing electrodes 14 and 16 against the substrates 10 and 12 with a sufficient force to bring the substrates 10 and 12 into close contact. Preferably, the substrates 10 and 12 are pressed with the electrodes 14 and 16 with a force in the range between about 600-1200 lbs per square inch. Preferable devices include an air cylinder and a servo motor. With respect to a servo motor, this device is more preferable in that it is able to quickly apply and remove the force needed to press substrates 10 and 12 together. In this manner, the force can be stationary or changed throughout the welding process. [0017]The magnitude of the electric current 18 is controlled to prevent, or at least substantially minimize, melting of the substrates 10 and 12 from occurring. In this regard, the electric current 18 heats the substrates 10 and 12, as well as the Zn coating 11 and 13 at the intended joining area or interface 19. It should be understood that controlling the magnitude of the electric current 18 is an important aspect of the present teachings because the Zn coating 11 and 13 has a melting point less than a melting point of the substrates 10 and 12. By controlling the magnitude of the electric current 18 passing through the substrates 10 and 12, as well as the Zn coating 11 and 13, the substrates 10 and 12 can be sufficiently heated to soften the substrates 10 and 12 without melting them. Notwithstanding, the magnitude of the electric current 18 is enough to reach the melting point of the Zn coating 11 and 13. The coating 11 and 13, therefore, is reduced to a molten form that is expelled or "squeezed" out from between the substrates 10 and 12. [0018]The coating 11 and 13 is expelled from the interface 19 between the substrate 10 and 12 at small gaps between the substrates 10 and 12 located in areas outside of and adjacent where the force is applied by the electrodes 14 and 16. Further, although not shown in the drawings, it should be understood that the coating 11 and 13 is sufficiently heated at the electrode/substrate interface such that the coating 11 and 13 is also expelled there. Moreover, it should be understood that the heating of the substrates 10 and 12 at the substrate/electrode interface causes thermal expansion at the substrate/electrode interface. Regardless, the force applied by the electrodes 14 and 16 is sufficient to enable face-to-face contact between the substrates 10 and 12 at the interface 19, but at the area outside and adjacent the interface 19, the substrates 10 and 12 may bend upwards to allow a gap to form. This gap may also be caused by thermal expansion of the substrates 10 and 12 during application of the electric current 18 of the substrates 10 and 12. [0019]The preferred magnitude of the electric current 18 is preferably in the range of 2 kA to 30 kA, and more preferably in the range of 2 kA to 14 kA. Although the ranges described above are preferred, one skilled in the art will readily acknowledge and appreciate that the electric current 18 should not be limited to the above ranges and can be set at any magnitude sufficient to soften any type of substrate known in the art. That is, although the present teachings are being described relative to joining substrates generally used in an automotive application, the present teachings should not be limited thereto. For example, the present teachings may be adaptable to preparing electronic devices where the substrates are formed of a material such as silicon (Si) or some other type of semiconductor material. In this regard, the current 18 needed to sufficiently soften the substrates 10 and 12 will be much less than the above-defined ranges. Continue reading... Full patent description for Hybrid resistance/ultrasonic welding system and method Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Hybrid resistance/ultrasonic welding system and method patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. Start now! - Receive info on patent apps like Hybrid resistance/ultrasonic welding system and method or other areas of interest. ### Previous Patent Application: Friction stir fabrication Next Patent Application: Apparatus and method for forming solder wicking prevention zone and electronic part Industry Class: Metal fusion bonding ### FreshPatents.com Support Thank you for viewing the Hybrid resistance/ultrasonic welding system and method patent info. IP-related news and info Results in 0.63746 seconds Other interesting Feshpatents.com categories: Canon USA , Celera Genomics , Cephalon, Inc. , Cingular Wireless , Clorox , Colgate-Palmolive , Corning , Cymer , |
||
