10 - Chapter 10 Threaded Fasteners and Power Screws 10.1...

Info iconThis preview shows pages 1–6. Sign up to view the full content.

View Full Document Right Arrow Icon
1 Chapter 10 Threaded Fasteners and Power Screws 10.1 Introduction A layman might consider threaded fasteners (screws, nuts, and bolts) to be the most mundane and uninteresting of all machine elements. In fact fasteners are used everywhere. There are more than 2 million fasteners on an airplane, cost over a million dollars. Engineers are concerned with the selection and use of fasteners, and they need to know choices available, governing factors and standards. Power screws are also commonly used machine components. Their engineering and design has much in common with that of threaded fasteners. 10.2 Thread Forms, Terminology, and Standards Fig. 10.1 illustrates a helical thread wound around a cylinder, as used on screw-type fasteners, power screws and worms. L = lead, p = pitch, λ = lead angle, and hand of thread. Virtually all bolts and screws have a single thread, power screws and worms have double, triple and even quadruple threads. Unless otherwise noted, all threads are assumed to be right-hand. Fig. 10.2 shows the standard geometry of screw threads used on fasteners. Figure 10.1 (p. 386) Helical threads of pitch p , lead L and lead angle λ .
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
2 Standard sizes for the two, Unified and ISO systems are given in Tables 10.1 and 10.2. Figure 10.2 (p. 386) Unified and ISO thread geometry. The basic profile of the external thread is shown.
Background image of page 2
3 Table 10.1a (p. 387) Basic Dimensions of Unified Screw Threads (Continued on next two slides.) Table 10.1b (cont.)
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
4 Unified threads are specified as size-threads per inch and series. For example: ½ in.-20UNF, 1 in.-8UNC. Metric threads are identified by diameter and pitch as M8 x 1.25. Fig. 10.4 illustrates most of the standard thread forms used for power screws. Standard sizes are given in Table 10.3. Table 10.3a (p. 390) Standard Sizes of Power Screw Threads (Continued on next slide.)
Background image of page 4
5 10.3 Power Screws Power screws, sometimes called linear actuators or translation screws, are used to convert rotary motion of either the nut or the screw to relatively slow linear motion of the mating member along the screw axis. The purpose of
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 6
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 12/01/2010 for the course MEM MEM 431 taught by Professor Jackzhou during the Fall '10 term at Drexel.

Page1 / 11

10 - Chapter 10 Threaded Fasteners and Power Screws 10.1...

This preview shows document pages 1 - 6. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online