Leistritz, best known for its whirling technology, is first to develop an innovative solution to machining difficult internal threads. The process–called internal whirling, which will be described in an in-depth article to appear in the March 2005 issue of Gear Solutions magazine–was originally developed for the ball screw industry, and it is featured in the Innovation 200 machine. Internal whirling eliminates and solves the inherent problems of thread grinding.
Internal whirling has none of the disadvantages of thread grinding yet produces a high quality, precision thread. The Leistritz Internal Tool System uses a supporting mandrel with a bearing placed close to the cut, enabling very large length to diameter ratios. Internal whirling eliminates a rough threading operation. Leistritz has developed its CBN technology to a state that their system can reliably and economically remove the full hardened steel to reveal a precision, finished thread in one pass. This is unheard of with grinding, which normally requires minimal stock removal.
As the tool rotates at cutting speed, it also oscillates axially. The amount of oscillation is calculated from the thread data. This very unique cutting action maintains the most true profile and ideal cutting characteristics. When the tool rotates out of the cut, it oscillates back to the beginning while continuing to rotate. This continues for each spindle rotation, and the workpiece is rotated in the same direction as the tool and the longitudinal axis of the machine is advanced at lead until the desired thread length is achieved.
The entire concept has recently premiered, but it has already proven itself in Europe with several ball screw manufacturers. In one installation an Innovation 200 machine is producing an automotive component with a six-start thread used in a light truck for automatic vehicle leveling. This tier 1 supplier is performing hard turning and hard internal whirling to produce 200,000 finished nuts annually.
Leistritz is a machine tool builder offering internal and external whirling solutions, rolling and burnishing equipment, and hydraulic keyseating machines. The company’s products are sold, supported with spare parts, and serviced by Leistritz Corporation of Allendale, New Jersey.
For more information call Ralph Wehmann, national sales manager, at (201) 934-8262, or send e-mail to rwehmann@leistritzcorp.com. The company’s Web site is [www.leistritzcorp.com].
