| 摘要 |
The flame of a cutting torch is passed through a central longitudinal zone of an elongated blank so that the kerf forms two rack sections with substantially identical teeth thereon. Rack sections with such flame cut teeth are secured together in side-by-side relationship, with their teeth in endwise register, to form a rack exceeding the thickness of the blanks from which the rack sections are cut. Before flame cutting of the teeth is commenced, thin slices are flame cut from opposite faces of the blank which are to become the backs of the rack sections, to prevent warping of the flame cut rack sections along their lengths. The machine from which the rack sections are cut is provided with a carriage to support a blank for lengthwise movement through a zone in which the torch is moved back and forth crosswise of the path of blank motion. Blank supporting means on the carriage permits free lengthwise expansion of the blank toward that end thereof which is first moved into the cutting zone, as the blank becomes heated by the flame of the torch, but precludes expansion of the blank toward its opposite end.
|
