The Four-Part Kinematic-chain - which you may call a 'four-bar mechanism', 'four-bar linkage', or even 'four-bar' - is the basis of the most frequently used mechanism in packaging machines.
This tutorial uses the Pin-Joint and Slide-Joint elements. We combine the joint with the Parts in different ways to configure the mechanism in different ways.
|•||To build kinematic-chains that have a total of four Parts and four Joints.|
|•||To learn about Dyads.|
Elements are the objects we add to the model. They represent the objects in a machine.
Nearly always: the sequence of steps we use:
In addition to elements that you can see in the graphic-area [Parts, Pin-Joints, ...], there are elements you cannot see [Constraints, ...]
The elements in Tutorial 1:
Parts are the elements that move relative to each other. They are 'rigid-bodies'. They remain coplanar to the Mechanism-Plane. [The Mechanism-Plane' is the Plane you select to add the Mechanism-Editor].
Base-Part: the fixed element on the Mechanism-Plane. Think of it as the machine frame.
Added-Parts [a different name for a Part]: the moving elements. They can move relative to the Base-Part.
Part-Outline: the 'symbol' for the element that represents a Part.
The Base-Part has a rectangular Part-Outline. A Part, or Added-Part, has an oval Part-Outline.
You cannot edit the shape of a Part-Outline. You select it when you want to edit a Part.
Part-Editor, Mechanism-Editor, Model-Editor.
Use the Part-Editor to edit an Added-Part and the Base-Part. You can add sketch-elements to Parts. You can edit the length of a Part. You can add constraints between sketch-elements.
Sketch-elements can define the position of Joints.
Use the Mechanism-Editor to build kinematic-chains, with Parts and Joints.
The kinematic-chain in Tutorial 1 has one Joint:
Kinematic-Chains are identified in the Kinematics-Tree.
A kinematic-chain has two or more Parts and one or more Joints.
The kinematic-chain in Tutorial 1 has two Parts:
The Added-Part became the 'Rocker', as defined in the Kinematic-Tree.
A Part that rotates, or oscillates.
The Rocker is made up of three elements:
Function-Blocks specify the motion for Rockers and Sliders.
Master Machine Angle
Master Machine Angle: the master-clock in the machine - it beats the drum for all kinematic-chains. It has a range of 0 to 360.
Mobility, Degrees-of-Freedom, kinematically-defined Parts
Parts have Green Part-Outlines or Blue Part-Outlines.
When a Part has a:
Kinematically-defined chains have a Mobility equal to Zero. Their position is completely defined by one or more Motion-Dimensions.
Kinematically-defined chains have an equal number of Motion-Dimensions as the Kinematic-Chain has degrees-of-freedom.
Kinematics of Beranys Steam Engine
This Bernays Engine has a number of Dyads, with only one Motion-Dimension.
At the end of this tutorial, you will be able to model kinematic-chains such as this.
Look at the YouTube video to see the solid model http://youtu.be/o3krPdVZW2g.
I apologise for the poor video. Make sure your speakers are off if you are in an open-plan office!