lecture9 - Inst. Charbel Seif, Mech 220 02/07/11 Mech 220...

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Unformatted text preview: Inst. Charbel Seif, Mech 220 02/07/11 Mech 220 Mech 220 Intro to Engineering CAD Intro to Engineering CAD FALL 2006-07 Inst.: Charbel Seif Office: Wing B - B-303 Extension: 3629 e-mail: [email protected] Non-Permanent Assembly Non-Permanent Assembly Symbols: FASTENERS Symbols: FASTENERS Inst. Charbel Seif, Mech 220 02/07/11 Mech 220: 9th LECTURE Mech 220: 9th LECTURE ASSEMBLY SYMBOLS: ASSEMBLY SYMBOLS: Assembly types Assembly types Elements of Permanent Assembly : • Riveting • Welding Elements of Non-Permanent Assembly: • Fasteners • Keys • Springs ◆ Assembly elements are used to hold parts together to assure proper functioning, or used to align one part to another or transmit motion and force. Inst. Charbel Seif, Mech 220 02/07/11 Mech 220: 9th LECTURE Mech 220: 9th LECTURE ASSEMBLY SYMBOLS: ASSEMBLY SYMBOLS: Fasteners History Fasteners History ◆ The earliest records describing screws are found in the writings of Archimedes. ◆ Most early Screws were made by hand. There we no interchanging of parts and nuts had be tied to their own bolts. ◆ The first attempt to standardize the screw thread production was in Unites states of America in the late 1864. ◆ The most recent standard for the Unified Inch Screw Threads is the ANSI B1.1-1989. Inst. Charbel Seif, Mech 220 02/07/11 Mech 220: 9th LECTURE Mech 220: 9th LECTURE ASSEMBLY SYMBOLS: ASSEMBLY SYMBOLS: Screw-thread terminology Screw-thread terminology External thread: External thread: a thread on the external surface of a cylinder Internal thread: Internal thread: a thread on the internal surface of a cylinder Major diameter: Major diameter: the largest diameter of a screw thread Minor diameter: Minor diameter: the smallest diameter of a screw thread Pitch diameter: Pitch diameter: the diameter of an imaginary cylinder the surface of which cuts the thread forms where the width of the thread and groove are equal. Crest: Crest: the edge that joins the sides of a thread and is farthest point from the cylinder Root: Root: the edge that joins the sides of adjacent thread forms and coincides with the cylinder from which the thread projects Depth of thread: Depth of thread: the distance between the crest and root measured normal to the axis Pitch: Pitch: the distance between corresponding points on adjacent thread forms measured parallel to axis Threads per inch: Threads per inch: the reciprocal of the pitch. Right-hand (left-hand) thread: Right-hand (left-hand) thread: thread that when viewed axially winds in a clockwise (counterclockwise) and receding direction. Inst. Charbel Seif, Mech 220 02/07/11 Mech 220: 9th LECTURE Mech 220: 9th LECTURE ASSEMBLY SYMBOLS: ASSEMBLY SYMBOLS: Thread form Thread form Form: the Form: the profile (cross section) of the thread ◆ “Thread form” describes the shape of the thread if one generates a section passing through the center of the thread....
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This note was uploaded on 02/07/2011 for the course MECH 220 taught by Professor Charbelseif during the Fall '06 term at American University of Beirut.

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lecture9 - Inst. Charbel Seif, Mech 220 02/07/11 Mech 220...

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