Shafting Fairfield University（轴系费尔菲尔德大学）.pdfVIP

Shafting Mission: Transmit power durably. Requirements: 1. Convey torque 2. Limit deflections (for gears, bearings, sprockets) 3. Limit stresses Features: 1. Steps or shoulders to locate bearings, gears, sheaves 2. Keyways or splines to transfer torque 3. Typically steady torque and alternating bending loads Stress and Deflection: Stress analysis is local 1. Bending moments and torsional shears are loads - independent of geometry 2. C/I and r/J are local geometries 3. Stress concentrations are local Deflection is a function of geometry everywhere 1. Deflection and slope are integrated buildup of bending/stiffness Attachments §11.6 Keys Keyways are usually sledrunner (K ~ 1.4), end milled (K 1.8), or Woodruff t t Key Failure Modes (P. 460): ß Shear on key = Torque / (key width * length * shaft radius) Ssy ß Compression = Torque / (0.5 * key height * length * radius) 0.9 S = S y cy Pins are limited by the shear area of the pin §10.56 Press/Shrink Fits (P. 420) Torque capability = Pressureinterface x Areainterface x interface x radiusinterface K is up to 2 at entrance and exit. t Screw Holding Set Screws (Cup Point; Source: SPS Unbrako) Size Force Tables show holding power (force) in LBs vs screw diameter. #8 385 LB Torque capability = holding power x radius of contact #10 540 LB ¼ 1000 L