【菜鳥成長記】20歲后，我在機(jī)械的每一天

黑森林的鹿

【20160324】Slider-Crank Mechanism
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Another mechanism that is commonly encountered is a slider-crank. This mechanism also consists of a combination offour links, with one being designated as the frame. This mechanism, however, isconnected by three pin joints and one sliding joint. A mechanism that drives a manual water pump is shown in Figure 1.37a. The corresponding kinematic diagram is givenin Figure 1.37b.
8 j/ _8 e6 f2 G0 S曲柄滑塊機(jī)構(gòu)也很常見。事實(shí)上它也是由4個構(gòu)件組成，只是其中之一被指定為機(jī)架。另外，此機(jī)構(gòu)是以3個轉(zhuǎn)動副、一個滑動副連接的。圖示為手搖泵及其運(yùn)動圖示。




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Because the slider-crank mechanism has one degree of freedom, it is constrained or fully operated with one driver. The pump in Figure 1.37 is activated manually by pushing on the handle (link 3). In general, the pivoted link connected to the frameis called the crank. This link is not always capable of completing a full revolution. The link that translates is calledthe slider. This link is the piston/rod of the pump in Figure1.37. The coupler or connecting rod “couples” the motion of the crank to the slider.
, L$ H3 r; \5 B* g因?yàn)闄C(jī)構(gòu)只有一個自由度，因此只需要一個主動力。一般來說曲柄無法完成整周運(yùn)動。作滑移運(yùn)動的構(gòu)件稱滑塊，連接滑塊和曲柄的稱連桿。
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黑森林的鹿

風(fēng)雪關(guān)懷 發(fā)表于 2016-3-24 13:13
, u! C/ ^- s) x, ]" j4 r3 c) G樓主有志氣，佩服佩服，加油

. L3 ~6 y$ ~, a7 O9 l不敢不敢，謝謝鼓勵！
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angle121

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黑森林的鹿

【20160325】Position and Displacement Analysis

7 ]1 `, S. `- |4 z" Y8 b3 ?8 nObjectives：
0 f6 K( S& j2 h- E: x2 z& n1. Determine the position of all links in a mechanism as the driver links are displaced.
/ _  W' o/ p# k( [4 m, B6 D: \4 m2. Determine the limiting positions of a mechanism.
/ d2 ]& C0 J) H: W' _目標(biāo)：
$ X. }! c: u! F* j6 X( P1.在主動件位置已知的情況下確定其余構(gòu)件的位置；
2.確定機(jī)構(gòu)的極限位置。
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Two types of methods

• GraphicalAnalysis
• AnalyticalAnalysis
  

兩種方法：圖示法、解析法

% f) R1 B! z8 n/ ~! c9 ^Position and displacement analysis：
* V7 p  @5 Q3 T% U# `! {1 ?' I1 hlocating the position of all links (configuration) in amechanism as the driver link(s) is displaced.
9 Y( b$ T: W# ~$ U& c/ w定義：在主動件位置已知的情況下確定其余構(gòu)件的位置。

Graphical Analysis
/ g+ u% \  {1 {6 v- H  A" m圖解法分析步驟

1.Point B moves to B’
2.Point C must always lay on its constrained path
3.The length between B and C must stay constant
: l# t) L; P+ U& S# A, _畫主動件→畫定軸轉(zhuǎn)動軌跡→連桿長度不變→交點(diǎn)
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1 f( J! P5 N/ k0 }2 ]: u7 g. B9 }Analytical Analysis
2 Q; s1 ~( o1 n+ H- h9 x解析法
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Limiting position
) i  T* J( ?6 f0 S* AThe configuration of a mechanism that places one of the follower links in an extreme location is called a limiting position.
! S, E/ i. x8 O從動件之一處于其極限位置的機(jī)構(gòu)位置稱極限位置。

3 ]5 S  M! _6 t5 y; F) kThe crank and coupler become collinear.
Imbalance angle - the angle between the coupler configuration at the two limiting positions.
曲柄和連桿共線時達(dá)到極限位置；
極位夾角：連桿在兩極限位置之間時所形成的角。
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0 j' m9 V9 {6 q: T% s% f5 u; uTransmission Angle
( M! X8 o9 Z4 @/ _The mechanical advantage ( output force/ input force) is proportional to the sine of the transmission angle.
傳動角：機(jī)械增益（輸出力比輸入力）與傳動角的正弦成正比。

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黑森林的鹿

【20160326】Mechanism design
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  {  D+ T4 G% A& D+ e  j: O" n. H& tThe task of mechanism design: given a desired motion, a mechanism form and dimensions must be determined.
結(jié)構(gòu)設(shè)計：根據(jù)運(yùn)動確定構(gòu)型。

8 M0 k+ w2 L  b5 J* e9 Z" }$ NSynthesis: describe the process of designing a mechanism that produces a desired output motion for a given input motion.
構(gòu)型綜合：描述給定輸入運(yùn)動實(shí)現(xiàn)輸出運(yùn)動的機(jī)構(gòu)設(shè)計過程。
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6 S/ h; ^: J7 C9 l分類：
3 c" J5 L6 o0 CType synthesis: selecting a mechanism type
Dimensional synthesis: determining the link lengths
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  r, p1 v2 B" @! x% S! NTime Ratio

Kinematically balanced mechanisms：the motion characteristics of the outward stroke are identical to those of the inward stroke.
: x% g( s" P0 U運(yùn)動對稱機(jī)構(gòu)：內(nèi)外沖程等時。
' d  `# Y8 h& L& v4 \1 K( PQuick-return mechanisms：difference in the speed of the forward and return strokes.
急回機(jī)構(gòu)：沖程不等時。
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* x$ k' b4 K) k# p5 xWorking stroke: smoothing the surfaces of metal. ( slower) 工作沖程
- y3 v. ^+ z) m5 TReturn stroke:nothing to do. ( quicker) 急回沖程

8 i) V6 q  l# I" f! jTime ratio: a measure of the quick return action of a mechanism
8 M5 ^5 ~, ]: ~- }7 B3 u* u時間比：用于度量急回機(jī)構(gòu)
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黑森林的鹿

【20160327】Design of Slider-Crank Mechanisms
曲柄滑塊機(jī)構(gòu)設(shè)計

In-line slider-crank mechanism: has the crank pivot coincident with the axis of the sliding motion of piston pin.
曲柄軸心與滑塊運(yùn)動軌跡共線。

2 T; W' v4 m% v# BIn-line slider-crank mechanism produces balanced motion.
該機(jī)構(gòu)產(chǎn)生平衡運(yùn)動。
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3 `2 b' |5 |6 @! C4 h; h" ?Offset slider-crank mechanism: has the crank pivot not coincident with the axis of the sliding motion of pin.
曲柄軸心與滑塊運(yùn)動軌跡不共線。

Determining an appropriate offset distance, L1, and the two links lengths, L2 and L3, to achieve the desired stroke, |ΔR4|max, and imbalance angle.
$ D: N6 e+ ]+ ^- j; o3 y確定補(bǔ)償距離及構(gòu)件桿長以獲得需要的沖程、極位夾角。

Questions
  P5 z) i" K# t. V  }. BThe stroke, |ΔR4|max, and imbalance angle are given, determining an appropriate offset distance, L1, and the two links lengths, L2and L3.
- @# E( q; d" K常見題型，給定沖程、極位夾角，確定補(bǔ)償距離及構(gòu)件桿長。

解題公式：

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黑森林的鹿

【20160328】Design of Crank –Rocker Mechanisms

The design of a crank-rocker mechanism-determining appropriate lengths of all four links to achieve the desired throw angle, (Δθ4)max, and imbalance angle, β.
# t1 a: [1 N+ S8 E4 Y, {曲柄連桿機(jī)構(gòu)設(shè)計：給定極位夾角求四桿長度。
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, v% r2 a  y3 U0 c8 ]! N2 i% F8 uQuestions:
% @5 U- U! Y5 ]The desired throw angle, (Δθ4)max, and imbalance angle, β are given.
Determining appropriate lengths of all four links.
8 y; D% D- Q6 {- e; F典型問題：
1 S# F# M" t% {( [8 f# E給定極位夾角求四桿長度。
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# O: B7 n0 ]* v9 Y2 t1 o6 Q( D, O計算公式：


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