Patent Application
20080182119
The disclosure relates generally to a method of welding, and more particularly to a method of projection welding.
Projection welding is a known technique for joining two overlapping metal sheets. In conventional projection welding, a small projection is provided on one of the sheets and extends transversely to a side of the sheet so that the tip thereof contacts the other sheet. A current producing device (such as an electrode of a welding gun) is pressed into contact with one of the sheets in alignment with the projection, and a combination of force and welding current is applied to the electrode to cause the projection to collapse and form a weld nugget which joins the two sheets together at the contact area defined by the projection.
Resistance projection welding is a solid state joining method, which eliminates the need for pre-heat that arc-welding methods require. Projection welding is also fast, which reduces manufacturing time. However, the properties of some metals render theses metals incapable of being directly welded to each other via this process. In addition, joints are very difficult to form in highly conductive materials, such as copper. Heat is conducted away from the joints rapidly, producing joints with defects. In welds, this can lead to lack of fusion and porosity. None-the-less, copper joints are essential in many applications, particularly in the magnetic coils of MRI equipment. Thus, there is a need for a more efficient forming of joints, and means for projection welding metals that are incapable of being directly welded to each other.
Disclosed is a projection welding method including providing a first metal substrate, a second metal substrate, and a projection material of separate construction from the first metal substrate and the second metal substrate, disposing the metal projection material between the first metal substrate and the second metal substrate, applying a current and pressure to at least one of the first metal substrate and the second metal substrate, melting the metal projection material via the application of the current and pressure, creating a weld between the first metal substrate and the second metal substrate via the melting, and fixedly associating the first metal substrate and the second metal substrate via the weld.
Also disclosed is a projection weld including a first metal substrate, a second metal substrate, a projection material separate from the first metal substrate and the second metal substrate, and a projection weld nugget including a mixture of the first metal substrate, the second metal substrate and the projection material.
Further disclosed is a projection welding method including providing a first metal substrate, a second metal substrate, and a metal projection material of separate construction from the first metal substrate and the second metal substrate, affixing the metal projection material to the first metal substrate, disposing the second metal substrate with the projection material and the first metal substrate such that the projection material is disposed between the first metal substrate and the second metal substrate, applying a current and a pressure to at least one of the first metal substrate and the second metal substrate, melting the metal projection material via the application of the current and the pressure, creating a weld between the first metal substrate and the second metal substrate via the melting, and fixedly associating the first metal substrate and the second metal substrate via the weld.
The following descriptions should not be considered limiting in any way. With reference to the accompanying drawings, like elements are numbered alike:
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It should be appreciated that prior to application of the current 26 to at least one of the substrates 12 and 14, one end 18 or 20 of the separately constructed projection 16 may be first fixed to one of the surfaces 22 or 24 via any desirable means, such as but not limited to conventional welding. The other of the surfaces 22 or 24 may then be disposed in proximity to (or in contact with) the other of the ends 18 or 20, and the current 26 and pressure 36 may be applied. As above, the current 26 and pressure 36 will then create a weld that will completely consume projection material 16. Thus, it should be appreciated that a projection (such as projection 16) would be contemplated to be of separate construction from the substrates 12 and 14, even when the projection 16 is fixed to one or both of the substrates 12 and 14 prior to application of the current and pressure (i.e. prior to creation of the projection weld nugget 33), as is discussed above with reference to one of the substrates 12 and 14. The projection 16 may also comprise the same composition as one or both of the substrates 12 and 14, and be considered to be of separate construction from the substrates 12 and 14, regardless of whether or not the projection 16 is fixed to one or both of the substrates 12 and 14 prior to application of the current and pressure.
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While the invention has been described with reference to an exemplary embodiment, it should be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or substance to the teachings of the invention without departing from the scope thereof. Therefore, it is important that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the apportioned claims. Moreover, unless specifically stated any use of the terms first, second, etc. do not denote any order or importance, but rather the terms first, second, etc. are used to distinguish one element from another.
