【菜鸟成长记】20岁后，我在机械的每一天

黑森林的鹿 · 发表于 2016-3-28 20:12:57

【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.
曲柄连杆机构设计：给定极位夹角求四杆长度。
未命名图片.png

Questions:
The desired throw angle, (Δθ4)max, and imbalance angle, β are given.
Determining appropriate lengths of all four links.
典型问题：
给定极位夹角求四杆长度。
未命名图片.png

计算公式：

apmc111 · 发表于 2016-3-28 21:05:47

加油，贵在坚持，希望你五年后还能来一篇总结

黑森林的鹿 · 发表于 2016-3-28 21:59:48

apmc111 发表于 2016-3-28 21:05
1 @% g! J: r/ C: @* Y加油，贵在坚持，希望你五年后还能来一篇总结

恩恩，会一直坚持下去的！感谢关注！

swj1234 · 发表于 2016-3-29 20:09:02

可以

黑森林的鹿 · 发表于 2016-3-29 21:35:31

【20160329】VelocityAnalysis

Velocity analysis : determination of velocity in a linkage.
速度分析：决定构件速度的分析。

Two common analysis methods：
Relative velocity method
Instantaneous center method
两种常用方法：相对速度法和速度瞬心法。

Relative velocity: the velocity of one object is related to that of another reference object, which can also be moving.
相对速度：两个均运动的杆件之间相对的运动速度。

VA = absolute velocity of point A
VB/A= relative velocity of pointBwith respect to A
相对速度的一些记法。

Instant center: a instantaneous pivot point about which the particular link instantaneously appears to be in pure rotation.
速度瞬心：在运动的瞬时可看做是旋转中心的点。

黑森林的鹿 · 发表于 2016-3-30 22:31:31

【20160330】Acceleration Analysis

Tangential acceleration 切向加速度

Normal acceleration 法向加速度

Total acceleration 和加速度
未命名图片.png

Relative motion: the difference between the motion of two points.
相对运动：两点运动的差（矢量）。
Relative acceleration: the acceleration of one object as observed from another reference object that is also moving.
相对加速度：一点相对于运动的另一点的加速度。
未命名图片.png

Coriolis Acceleration 科氏加速度
未命名图片.png

The magnitude of the Coriolis component:
未命名图片.png

Both the relative linear velocity and the absolute angular velocity can be determined from a thorough velocity analysis.
计算科氏加速度的量可以从运动学分析中得到。

黑森林的鹿 · 发表于 2016-3-31 21:27:03

【20160331】Cams: Design and Kinematic Analysis

Cha 07-2016.jpg

The camshaft is driven by the engine.
As the cam rotates, a rocker arm drags on its oblong surface.
The rocker arm imparts a linear, reciprocating motion to a valve stem.
The spring is used around the valve stem. The rocker arm follower needs to maintain contact with the cam surface to achieve the desired motion.
发动机中控制阀门进排气的凸轮。应用弹簧使杆件与凸轮保持接触。

The unique feature of a cam
Cams can be used to obtain unusual or irregular motion that would be difficult or impossible, to obtain from other linkages, because the motion of cams can be prescribed.
凸轮的特点：凸轮可实现一般杆件不能或难于实现的功能。

however1241 · 发表于 2016-4-1 18:18:30

又来看楼主了，楼主还在更新着。

黑森林的鹿 · 发表于 2016-4-1 20:03:19

【20160401】Type of Cams
$ q) B b% e5 F1 u! }: N$ ~8 k0 ~0 m凸轮分类

Plate or disk cams
This type of cam is formed on a disk or plate.
The radial distance from the center of the disk is varied.
平面凸轮：在平面内形成的凸轮，与中心的径向距离是变化的。

Cylindrical or drum cams
A groove is cut into the cylinder, with a varying location along the axis of rotation.
The follower is attached to the groove, thus giving the follower motion along the axis of rotation.
圆柱凸轮：柱体上刻有凹槽，沿轴向变化分布，从动件被限制在凹槽内，因此沿轴向运动。

Linear cam
A groove is cut into the block with a distance that varies from the plane of translation.
Attaching a follower in the groove gives the follower motion perpendicular to the plane of translation.
线凸轮：在板内刻有线型凹槽，从动件运动垂直于板的传动方向。

however1241 · 发表于 2016-4-2 08:11:11

however1241 发表于 2016-4-1 18:18
) M7 A5 A4 b, G* h# b9 g3 x9 [% P Q又来看楼主了，楼主还在更新着。

老鹰版主会鼓励吧。

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【菜鸟成长记】20岁后，我在机械的每一天

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