HI

MAKING YOUR ASSEMBLIES DYNAMIC BY PRO – MECHANISM

Mechanism

      A mechanism is a device designed to transform input forces and movement into a desired set of output forces and movement.

Pro-Mechanism is a very useful module to design the mechanism and to know the dynamic path of the parts, interference in an assembly.

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Bodies

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Connections of Bodies

ØMost Used Connections

ØPin

ØCylinder

ØPlanner

ØSlot

ØBall

ØSlider

ØAlso, we have

ØBearing

ØRigid & weld

ØGeneral

Ø6DOF

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Connection - Pin

The pin connection is used to rotate the part about an axis.

Examples:-

üDoor that swings open

üWheel that turns

Pin - axis alignment and a translational constraint 

Joint Axis settings on Rotational motion

   Joint Axis setting is used for control the rotation of a part with some specified angle like 0 deg to 180 deg.

 

Drag - Drag is the option is used for check the motion of the rotating part manually.

Servo Motor – Animate the part  & Run the assembly.

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Connection - Cylinder

The cylinder connection is used to capture a component moving in a direction, and able to rotate about that direction

Examples:- 

üCycle air pump

üPiston action on cylinders

Joint Axis settings on Parallel Motion

  Joint Axis setting is used for control the distance  of a moving part within specified distance like 1 to 50 mm.

Reverse Servo Motor – Animate the part

Run the assembly.

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Connection - Planer 

A Planar connection is used to ensure that a datum plane or planar surface always touches another plane or planar surface,

Examples:-

üLM Guide Rail & Runner Block

üA box sliding across a floor

üAny object that rests on a flat surface, but can be moved about that surface.

üPlaner  - Plane moves on Plane

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Connection - Slot

Slot Connection is used to move a component along a path.

 

Examples:

Bevel Gauge

Geneva Mechanism

Slot – Point Moves on Curve

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Connection - Ball

ball connection is used to simulate a joint where the translation is completely fixed, but all rotational degrees of freedom are available.

Examples:-

Toggle Switch

Ball joint gas springs

Ball Connection - require two points or vertices to be aligned, and they have no joint settings.

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Cam Follower

A Cam-Follower is used to simulate an object moving along the surface of another object.

Example-  All Cam design applications

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Gear Connection

Gear pairs are used to simulate two gears in mechanism

Standard – Use this when you want your two gears to rotate in the same or opposite directions, such as a spur-spur or worm and wheel gear.

Rack and Pinion – Use this when you want to be able to translate rotational motion into translational motion.

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Interference checking & Create a movie file 

We can capture a playback result set as an MPEG file, or as a series of JPEG, TIFF, or BMP files by using playback option.

· Start Time = 0

· End Time = 10

· Frame Rate = 10

· Minimum Interval = .1

· Frame Count = 101     

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Summary

COMPONENTS OF MECHANISM

  

Step 1 – Assemble Components

Step 2 – Modify Joint Axis Settings

Step 3 – Create Cams or Gear Pairs

Step 4 - Drag Components

Step 5 – Create Servo Motors

Step 6 – Create and Run Analyses

Step 7 – Check interference & Create a movie file

Connection Type	Translational DOF	Rotational DOF	References Needed
Pin	0	1	2 Axes or Edges & 2 Planes, Planar Surfaces, Datum Points or Vertices
Slider	1	0	2 Axes or Edges & 2 Planes or Planar Surfaces
Cylinder	1	1	2 Axes or Edges
Planar	2	1	2 Planes or Planar Surfaces
Ball	0	3	2 Datum Points or Vertices
Bearing	1	3	1 Datum Point and 1 Axis or Edge
Weld	0	0	2 Coordinate Systems

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PRACTICE MAKES YOU PERFECT

THANK YOU

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Ref- Sharptechdesign web.

Pro-Mechanism

COMPONENTS OF MECHANISM

In addition to being able to assemble components using realistic degrees of freedom, mechanism also does a lot more.  The typical progression to using mechanism is as follows.

Step 1 – Assemble Components

Create your assembly using mechanism connections to capture realistic degrees of freedom.  These connections are covered in great detail in the upcoming lessons.

Step 2 – Modify Joint Axis Settings

Control your connections by modifying the joint axes created by the connection.  This is explained in greater detail in the connection lessons individually.

Step 3 – Create Slots, Cams or Gear Pairs

Slots, Cams and Gear Pairs are special tools in mechanism that capture complex interactions between components.  These will each have their own lesson.

Step 4 - Drag Components and Create Snapshots

Dynamically pull or push on components that have open DOF to see them move in the assembly.  Take snapshots of your assembly at different states of motion to use in drawings or to come back to for reference.

Step 5 – Create Servo Motors or Force Motors

Servo motors and Force Motors are used to drive analysis and move your assembly on their own without using drag tools.  Each of these topics will be covered in great detail in their own lessons.

Step 6 – Create and Run Analyses

Start your animations to calculate the results you are looking for.  With servo motors in your assembly, you will be able to produce motion animations.  With Force motors, you will be able to calculate resultant forces and other measures while the animation is running.

Step 7 – View Results and Take Measurements

Run the animation to create MPEG movies, or to calculate interference along the path of the moving objects.  Create and view graphs that measure certain factors over time, such as position or force.

CONNECTION TYPES

The table at the top of the next page lists the different connections available through the component placement window at the time you assemble in a component.  In addition, the number of translational and/or rotational degrees of freedom are shown for each connection type.

Connection Type	Translational DOF	Rotational DOF	References Needed
Pin	0	1	2 Axes or Edges & 2 Planes, Planar Surfaces, Datum Points or Vertices
Slider	1	0	2 Axes or Edges & 2 Planes or Planar Surfaces
Cylinder	1	1	2 Axes or Edges
Planar	2	1	2 Planes or Planar Surfaces
Ball	0	3	2 Datum Points or Vertices
Bearing	1	3	1 Datum Point and 1 Axis or Edge
Weld	0	0	2 Coordinate Systems

There are two additional connection types in the list, but they don’t fit into the categories above.  These are the Rigid and General connections, and they allow you to use standard assembly placement constraints, such as Align, Mate, Insert, Tangent, etc.  We will see its usage in Mechanism later.

Ref - http://www.sharptechdesign.com/Tutorials/Mechanism_WF2/MDX_WF2_Lesson01.htm

Top Down Design

TOP-DOWN DESIGN

The idea behind Top-Down design is to try to build in intelligence between the fit, form and function of parts that reside in an assembly.  You try to capture this fit, form and function into the assembly first, and then pass the appropriate information down to the part level so that a change made at the assembly level or to one component in the assembly can drive updates to the rest of the critical parts.

In this method, many of the components are created in the assembly, instead of being assembled into the assembly.

SKELETON MODELS

The best way to capture fit, form and function for the assembly is to create a special kind of component called a Skeleton Model.  A Skeleton model is similar to a regular part, but it is treated specially in the assembly.  For example, a skeleton model is automatically excluded from the Bill of Material, where if you just created a regular part and used it like a skeleton, it would still be reported.

There are also restrictions that can be placed on regular parts that skeleton models are exempt from, or get special rights to deal with.  For example, you can make it so you are not allowed to copy surfaces from a regular part to another regular part, but you can still pass surfaces from the skeleton model to a regular part.  In defining such restrictions, you avoid creating parent-child relationships between individual part files, making the model more robust.

To demonstrate this principal, we will first create a new assembly file called Stacker.  Be sure to use a Design sub-type for this assembly, just as we did for the last lesson.  Also, once you have the assembly started, be sure to turn on the features in the model tree.

Bottom Up Design

PLACEMENT CONSTRAINTS

If you recall, when we first got into the placement window for a new component, the current constraint was listed as Automatic.  It was awaiting entity selection to determine automatically which of the pre-defined constraints made the most sense.  I would recommend starting off with Automatic and then adjust the constraints accordingly.  In this section we will look at the pre-defined constraints that can be assumed or selected directly.

Mate

A mate takes two surfaces and points their normals towards each other and lines up both surfaces, as shown in the next figure.

Mate Offset

This is the same as a Mate except that the distance between the surfaces can be less than or greater than zero.

Align

An Align takes two surfaces and points their normals in the same direction and lines up both surfaces, as shown in the next figure.

Align Offset

This is the same as an Align except that the distance between the surfaces can be less than or greater than zero.

Orient (Parallel)

This is similar to an Align offset, except that you don’t specify the distance between the surfaces. 

Insert (Coaxial)

An insert takes two cylindrical surfaces and lines up their axes, as shown in the next figure.

Tangent

A Tangent constraint takes two cylindrical surfaces, or a planar and cylindrical surface and makes them tangent to each other, as shown in the next figure.

Point on Surface

Places a datum point or vertex on a surface, as shown in the following figure.

Edge on Surface

Places a straight edge on a cylindrical or planar surface, as shown in the next figure.

Sheet Metal Best way of modeling

Step 1 - Add first flange
Step 2 - thickness value should be mentioned in relation ex t=1.2
Step 3 - Say inner radius in relation ex IR=1.5
Step4 - For manual Relief cuts, add relation &ad15 = IR+t

If we create a sheet metal model by using relations, we change thickness of the part without failures when iteration during analysis.

Cheers!  

Thread callout in pro-e

&METRIC_SIZE &THREAD_SERIES - &THREAD_CLASS &STD_HOLE_TYPE &VAR_THREAD &THREAD_DEPTH
&NUMBER_SIZE DRILL ( &DIAMETER ) &VAR_DEPTH &DRILL_DEPTH  -( &PATTERN_NO ) HOLE