Metal parts can be economically fabricated by a metal stamping that comprises preforming a piece of wire to have a shape corresponding to the 2-dimensional configuration of a desired product workpiece, flattening the wire to form a metal blank, and subjecting the metal blank to metal stamping to obtain the desired product workpiece. The process can significantly reduce the amount of scrap material and thereby reduce manufacturing costs.
Metal parts are fabricated by a variety processes such as casting, die casting, and forging. One of the more common processes used for manufacturing metal parts is called metal stamping, which has been in use for over 150 years. Metal stamping,which in general involves taking a flat metal sheet and converting into a shaped article (i.e., a metal part) using a die and press, is a cost-effective process because it permits metal parts to be manufactured at high production rates.
In a conventional metal stamping process, a sheet of metal stock material, such as aluminum, copper, zinc, steel, stainless steel, nickel, titanium, or the like, is introduced into a stamping press such as a mechanical or hydraulic stampingpress. The stamping press has a die means and a punch means which together are used to form blanks from the initial sheet of stock material. These blanks are then subjected to further stamping procedures to form metal parts.
A disadvantage of conventional metal stamping processes is that the formation of the blanks from the initial sheet of stock material and the subsequent further processing of the blanks into metal parts can result in generation of excessiveamounts of scrap material, thereby adding to the cost of manufacture due to both loss of material and cost of waste disposal.
After the preforming stage, the shaped wire or preform is then subjected to a flattening process to achieve a "blank" from which the desired product workpiece will be obtained via a stamping process. The term "wire" as used herein is not to belimited to wires having circular cross sections. Wires of other cross sections such as square, rectangular, etc can also be used. Further, the effective diameter of the wire can vary widely depending on the desired thickness of the metal part and theflattening process. The wire can be flattened by any typical process suitable for applying the requisite pressure to a piece of metal. For example, a shaped section of wire having an effective or nominal diameter of, for example, 3 to 50 mm, preferably5 to 20 mm, can be flattened to a preformed piece of metal having a thickness of, for example, 1 to 30 mm, such as 1 to 25 mm or 8 to 30 mm, preferably 2 to 8 mm, by passage through a mechanical or hydraulic press that applies a pressure of, for example,60 to 1000 tons, preferably 100 to 600 tons. The dimensions and tonnage listed above are merely provided as examples and are not intended to limit the invention.
Thus, the width and thickness of the blank are determined by the selection of the nominal diameter of the wire and the amount of pressure imposed during the flattening process. The length of the blank is determined primarily by the performingstage, by selecting the length of the wire and it's perform shape prior to the flattening step, although the flattening step will also influence the overall length of the blank.
This procedure, in which the blank is made from a flattened preformed wire, results in considerable savings in material costs as the blank obtained from the flattened preformed wire requires far less material than a conventional blank obtainedfrom a metal sheet. In other words, in a conventional procedure blanks are cut and formed from a sheet of flat rolled metal. This procedure inherently imposes material costs due to the resultant scrap material. Yet, in the process according to theinvention, the blank is formed with little or no material loss.
After the preform is converted into a blank, the blank can then be subjected to one or more further conventional metal stamping procedures. In such procedures, the blank can, for example, be "stamped" in a die and press arrangement such as in amechanical or hydraulic press whereby excess material is trimmed from the blank to form a desired product workpiece, either a final product or an intermediate thereof. A typical metal stamping machine is a Minster.RTM. 200 ton mechanical press.
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