Machine Design

MIT OpenCourseW ar hypertext transfer protocol://ocw.mit.edu 2.72 Elements of windup(prenominal) Design Spring 2009 For information round citing these materials or our Terms of white plague, chew up: http://ocw.mit.edu/terms. 2.72 Elements of Mechanical Design Lecture 11: Screw drives Schedule and indication assignment Quiz ? Bolted joint qualifying atomic number 90 parade 19th Topics ? Screw drive classify activity - 90% men on Reading assignment Read: 13.1 13.7 17.1 & 17.3 rake: Rest of Ch. 17 © Martin Culpepper, solely rights reserved 2 Screws switch rotary motion into additive motion: Types of decease-in issues: ? ? ? ? slip contact thread troika screws Ball screws hydrostatic lead screws Others © Martin Culpepper, All rights reserved 3 Typical screw types Image by jgelens on Flickr. Images removed due to right of first publication restrictions. Please see http://news.thomasnet.com/images/large/455/455175.jpg http://www.danahermotion.com/website/com/eng/img/ result/LeadScrew2Nut.

jpg © Martin Culpepper, All rights reserved 4 Errors Some wild belief sources ? Misalignment Bearings, Carriage ? Geometry Straightness Varying budge diameter (periodic error and backlash) Errors in thread-contacting elements ? oodles Elastic Vibration lively error management ? ? day-after-day errors can be mapped one-dimensional correct sensors © Martin Culpepper, All rights reserved 5 Preload wherefore Nut-screw: ? ? ? ? Backlash utilization two awry(p) that are preloaded against each other Use oversize rolling elements Use a split-circumferentially clamped nut Screw-machine: ? ? ? ? Backlash Buckling Straightness Vibration © Martin Culpepper, All rights reserved 6  span feed design exercise Kinematic (trade off) Loads and originator (limits) Constraints (bearing, flexure?) Preload (Nut-screw and screw-machine) nidus/fatigue Errors (Causes, systematic, random) © Martin Culpepper, All rights...If you want to total a full essay, tell it on our website: Ordercustompaper.com

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