A. |
The diameter of the blank to be rolled approximates to the pitch diameter of the thread to be rolled. Adjust the head to size by using a rolled component or plug gage, then roll a thread and measure the pitch diameter. Then increase the blank diameter until the major diameter falls within limits. Keep in mind that for every .001” increase in the blank major diameter will increase .003. The component must have a chamfer from 10 degrees to 30 degrees from the axis of the component starting from .020 to .040 below the minor diameter of the thread. If there is an undercut the chamfer must be the same. During the rolling operation the chamfer will grow to 15 degrees making a 30-degree chamfer 45 degrees. |
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B. |
Blanks should be round and straight, as a rolling head will not correct inaccuracies. Uneven distribution of rolling pressure will over load the rolls; reduce roll life and cause unnecessary head maintenance. |
C. |
Blank diameter tolerances have a definite relationship to the thread being produced, as a general rule the blank diameter tolerances for unified and metric threads approximates to one third of the pitch diameter tolerances. |
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