機(jī)械設(shè)計(jì)5第56章連接(已修改)
2025-01-20 15:12 本頁面
【正文】 Part I Connections Types Static connection→Releasable connections such as thread, key and pin connections。 Nondetachable connections such as weld, bonding and riveting c onnections Motion connection→Kinematic pair 167。 5— 1 Thread Righthand and lefthand threads: A righthand thread is one that advances into a nut when turned clockwise (figure a). A lefthand thread is on the advances into a nut when turned counterclockwise (figure b). A thread is always considered to be righthanded unless specified otherwise. A lefthanded thread is always labeled (LH) on a drawing. (I) Main parameters of threads: Single and Multiple Threads: A single thread is posed of one ridge (脊 ) and the lead is equal to the pitch (齒距 ) (figure a). A double thread is posed of two ridges and the lead is equal to twice the pitch (figure b). A triple thread is posed to three ridges and the lead is equal three times the pitch (figure c). Three diameters： ｄ (Major Dia.(大徑 )－ Standard Dia.(標(biāo)準(zhǔn)直徑 )) ； ｄ 1(Minor Dia. (小徑 )) ； ｄ 2(Pitch Dia. (中徑 )) Two heights： p(pitch, 螺距 )；Ｓ (Lead, 導(dǎo)程 ) ； ｎ (Number of threads, 螺旋線數(shù) )。 Ｓ＝ n p。 Ψ(Helix angle, 升角 )。 a— (Thread angle, 牙型斜角 )。 tgψ＝ n p／ πｄ 2 Πｄ 2 S ψ (II) Types and applications of threads (Table 51) Connecting threads (聯(lián)接螺紋 ): Plain thread, Gas thread (管螺紋 ) Transmission threads (傳動(dòng)螺紋 ): Rectangular thread, trapezoidal thread (梯形 )。 Sawtooth thread (鋸齒形 ) 1. Connecting (triangular) threads Plain thread(普通螺紋 ): α＝ 60176。 large α leads to large f ′, easy to selflock Coarse thread (粗牙 ): small d1, big ψ Thury thread (細(xì)牙 ): large d1, small ψ, more easy to selflock Gas thread： (British system, 英制 )→α＝ 55176。 →tight (Metric system, 米制） →α＝ 60176。 →tight 2. Transmission thread small α, big ψ, multiple threads, high efficiency ┌ Trapezoidal thread (Tr) α＝ 30176。 β＝ 15176。 ├Sawtooth thread (S) α＝ 33176。 βw＝ 3176。 βnw＝ 30176。 └Rectangular thread (R) α＝０ 176。 ( or α＝ 1０ 176。 ) Working surface Feed screw of a machine tool Forcing press (壓力機(jī) ) I． Fundamental types of the threaded connection* 167。 5— 2 Types of the threaded connection and the standard connecting pieces 1. Bolt Connection(螺栓聯(lián)接 ) Plain bolt connection: There is clearance between the hole and the bolt, it is convenient to install and monly used. Connection with reamed hole (鉸制孔 ), hole basis (基孔制 )，transition fit (過渡配合 , H7/m6,H7/n6） ： No clearance, with high costs 2. Studded Connection(雙頭螺柱聯(lián)接 ) It is used when one of the connection pieces is very thick 3. Screw connection (螺釘聯(lián)接 ) 4. Holding screw connection（ 緊定螺釘連接 ） 5. Special screw connection Ground screw connection (地腳螺釘聯(lián)接 ) Lifting bolt connection (吊環(huán)螺釘聯(lián)接 ) I． Standard ponents of threaded connections Bolt－ Bolt ； Screw ； Threaded stud ； Holding screw Nut (螺母 )－ Hexagon nut(六角螺母 )； Round nut。 Round nut with grooves Gasket (墊片 )－ Flat gasket(平墊片 ) ； Spring shim (彈簧墊片 )； Bevel washer (斜墊片 )； Spherical washer (球形墊片 ) According to GB/T , ponents of threaded connections includes three accuracy classes, ., Aclass, Bclass and
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