JUSTAR
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rapid traverse Machining Technology in Brief Faster Setup for Centerless Grinders By Mark alBert enterless cylindrical grinding is fast, precise and productive, especially for manufacturing small, long or slender workpieces. However, setting up or retooling the typical centerless machine can require many hours from a skilled operator, often relying on experience and intuition “to get it right.” For this reason, the process generally has been favored for high-volume applications, and less so for small- to medium-sized batches. The new series of Jupiter centerless cylindrical grinding machines from Erwin Junker Machinery (Elgin, Illinois) addresses this limitation. A heightadjustable work rest blade and control software to establish exact blade position were developed by the company’s parent in Germany. These developments shorten setup, thereby reducing the time required to produce the first good part. The machines in this series (the Jupiter 125, 250 and 500) are capable of straight (through-feed) and angular plunge-cut grinding. Angular grinding is required for any part on which shoulders are ground, including workpieces recessed with different diameters. To make this grinder particularly suitable for high-precision applications, the company combined both grinding operations in a single machine. The regulating wheelhead can be pivoted horizontally and has a permanently affixed work rest blade. During grinding, the regulating wheel presses the part against the grinding wheel profile at an angle. This also makes it possible to grind highly complex par ts with multiple rece sse s. T he grinding The Jupiter 125 centerless cylindrical grinder combines straight and angular plunge-cut grinding. Machines in this series are designed for fast, simplified setup.

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rapid traverse Machining Technology in Brief Centerless grinding is characterized by a grinding wheel and a regulating wheel rotating in opposite directions. The workpiece is supported underneath by a blade that can be adjusted automatically for the optimum height setting on the Jupiter grinders. Straight plunge-cut grinding of a shaft is shown here. wheelhead is designed to be rigid and has just one infeed axis. The height-adjustable work rest blade is a programmable feature that comes with special control software to automatically calculate the optimum position of the blade. These...

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rapid traverse Machining Technology in Brief angles; that is, the contact angle of the regulating wheel and the angle to the work rest blade, resulting in different contact points. So as the wheel wears down, different angles are produced, and the roundness gets worse.” Existing software that compensates for these changes generally sets the process more or less in the middle between minimum and maximum wear, he says. In an application that requires roundness values of a few tenths of a micron, this compromise is often inadequate. “At best, you can get down to an accuracy of one or two...

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