03-10-2012, 03:36 PM
Threads and Thread Cutting
Threads_and_Thread_Cutting.ppt (Size: 1.02 MB / Downloads: 222)
Threads
Thread
Helical ridge of uniform section formed on inside or outside of cylinder or cone
Used for several purposes:
Fasten devices such as screws, bolts, studs, and nuts
Provide accurate measurement, as in micrometer
Transmit motion
Increase force
Thread Terminology
Screw thread
Helical ridge of uniform section formed on inside or outside of cylinder or cone
External thread
Cut on external surface or cone
Internal thread
Produced on inside of cylinder or cone
Pitch diameter
Diameter of imaginary cylinder that passes through thread at point where groove and thread widths are equal
Equal to major diameter minus single depth of thread
Tolerance and allowances given at pitch diameter line
Thread Forms
ISO Metric
American National Standard Thread
British Standard Whitworth (BSW) Thread
Unified Thread
American National Acme Thread
Square Thread
Brown & Sharpe Worm Thread
International Metric thread