Week 10- Assembly Workbench

Assembly workbench

Aim

To create assemblies of quick return mechanism and CV joint and to also create 2D drawing of the given assemblies in CATIA.

Assembly:

Assembly model is a technology and method used by CAD and product visualization computer software systems to handle multiple files that represent components within a product. The components within an assembly are represented as solid or surface models. The assembly constraints allow you to restrict the degrees of freedom of components on their respective work positions.

Assembly workbench:

The assembly files in Catia are called product files, there are two methods to invoke the assembly Design work bench in Catia, the primary method to start a new product file is by selecting File>New from the menu bar to open the new dialog box from this dialog box from this dialog box select product. The other method of invoking the assembly Design workbench is by choosing start>Mechanical Design>Assembly Design from the menu bar.

• Types of assembly design approach:

In Catia you can create assembly models by adopting two types of approaches. The first design approach is the bottom-up approach, And the second one is the top-down approach, both these design approaches are discussed below.

• Bottom-up Assembly:

The bottom-up assembly is the most preferred approach for creating assembly models, In this approach the components are created in the part design workbench as (*.CAT part) file. Then the product (*. Cat product) file is started and all the previously created components are inserted and placed in it using the tools provided in the assembly design workbench.

After inserting each component, constraints are applied to position them properly in the 3D space with respect to the other components.

• Top-down Assembly –

In the top-down assembly design approach, components are created inside the Assembly design Workbench. Therefore, there is no need to create separate part files of the components. This design approach is completely different from the bottom-up design approach, here you have to start the product file first and then, one by one, create all components, note that even though the components are created inside the product life, they are saved as individual part files and can be open separately later.

Note: An assembly can also be created by using the combination of both the top-down and bottom-up assembly design approaches.

How does constant velocity joint work?

Constant velocity, or CV joints are used to connect your Vehicles transmission to your wheels, CV joints are part of the Driveshaft and are used primarily on front wheel drive vehicles but they are also used in rear- and four wheel drive vehicles, Each drive wheel has two CV joints, inner point connects the transmission to the axle, and the outer joint connect the axle to the wheel, The CV joints name comes from its ability to move with your vehicles suspension in any direction (If your vehicle hits a pothole or an uneven surface) and still be able to keep the drive wheels moving at a constant velocity. The CV joint is a very special joint: it connects two different rotating shafts; these two rotating shafts are stuck in a fixed position.

So, The CV joint must be able to move and bend to keep these two shafts connected, CV joints are being used in newer vehicles and are taking the place of the old ‘’U ‘’ joints. The CV joint is able to transmit Even levels of the torque to the wheels continually no matter what angle it’s in. This means that no matter how many potholes you hit, or if the vehicle is turning, The CV joint keeps the drive wheel moving at a constant velocity.

Now we will see CV joint Assembly which consist of 5 parts in which few parts are identical which we can duplicate/copy later.

Moving and rotating using manipulation tool

The manipulation tool is used to move or rotate the component freely by dragging the cursor, To translate or rotate any component, Choose the manipulation button from the move toolbar,

CV Joint Assembly:

• Create an all sketch by using positioned sketch command.
• Ensure all the sketches in iso constrained.

• Use pad command to thicken solid for all the above sketch.

ASSEMBLE ALL CAT part

• Create a new CAT product and insert all the above separate CAT part by using existing component command.
• Create a reference element for all CAT parts.
• Add reference element like axis, points, whenever we need
• Use publication tool to make all the necessary elements like planes, points, axis, to make visible.
• Make the reference part fixed.
• Now using Constrain, offset tools assemble each part to one another.

TREE STRUCTURE:-

DRAFTD DRAWINGS

ASSEMBLY 2

Quick return mechanism:

1. A quick return mechanism is an apparatus to produce a reciprocating motion in which the time taken for travel in return stroke is less than in the forward stroke. It is driven by a circular motion source (typically a motor of some sort) and uses a system of link with 3 turning pairs and a sliding pair, A quick return mechanism is a sub class of a slider crank linkage, with an offset crank.
2. Quick return is a common feature of tools in which the action is performed in only one direction of the stroke. Such as shapers and powered saws because it allows less time to be spent on returning tool to its initial position.

Procedure:

1. Create an all sketch by using positioned sketch command.
2. Ensure that all the sketches in iso constrained.

1. Use pad command for thicken solid for all the above sketch.

Assemble All CAT part

• Create a new CAT product and insert all the above separate CAT part by using existing component command.
• Create a reference element for all CAT parts.
• Add reference element like axis, points, whenever we need
• Use publication tool to make all the necessary elements like planes, points, axis, to make visible.
• Make the reference part fixed.
• Now using Constrain, offset tools assemble each part to one another.

TREE STRUCTURE:-

DRAFTED DRAWINGS: