| 摘要 |
<p>This invention relates to tubular ferromagnetic inductive elements and to a process for producing air gaps in them. Ferrites used to make ferromagnetic inductive elements are ceramics and, therefore, elements made from ferrites are hard and brittle. Their brittleness subjects them to breakage, and their hardness makes alteration of them after they are fired expensive, since grinding or carbide cutting is usually required. There is a need for an economical gapped tubular inductive element. Prior art techniques cannot economically produce such an element because of the hardness and brittleness of the material. According to the present invention, tubular ferromagnetic elements are held in a fixture which moves them axially past a laser beam focused on the tube so that an axially elongated slot is formed in the wall by vaporization of material. Effect of the laser beam on the inner wall opposite the slot is minimized by defocusing of the beam as it passes through the bore of the tube, adjustment of the rate of movement, and/or use of a temporary filler piece in the bore. Interruption of the beam while the tubular element continues to move can produce "ties" between slots which give a mechanically stronger product.</p> |
