Advanced Sheet Metal Design Using NX Cad Challenge_2_Box Assembly

Advanced Sheet Metal Design Using NX CAD- Box Assembly Design

Objective:

The main objective of this project is to design a sheet metal casing in NX cad sheet metal application workbench. Also, to perform the drafting for the BOX ASSEMBLY part.

Software used: NX 12.0

• To design and model the sheet metal Box assembly in NX by using some basic features.

• To learn to create sketches on defined planes as per requirement.

• To master the user interface and basic features of Sheet metal application in NX like Tab, Flange, Break corner, Unbend, Creating holes, Re-bend, Dimple, Bead, cutout, Mirror feature, and Flat pattern etc…

Introduction:

Sheet metal is any metal that has a thickness in between 0.5 mm and 6 mm. Any metal piece thicker than 6mm are considered as Structural Metal (for ex. Structural Steel) and any metal piece having thickness lower than 0.2mm is called Metal Foil (for ex. Aluminum Foil).

Sheet metal is one of the fundamental forms used in metalworking, and it can be cut and bent into a variety of shapes. It is found in various industrial application ranging from small and light Fixture to an Automotive Body Part. Sheet metal applications have wide range due to its properties like: High Strength, Low weight and Corrosion Resistance.

General Sheet Metal materials are Steel, Aluminum, Brass, Titanium. There are 2 ways of producing Sheet Metal – Hot Rolling and Cold Rolling. For precision applications, cold rolled steels are preferred as manufacturers have more control over the final dimensions. This is because in hot rolled steels, after cooling, the steel shrinks slightly and the shape might change a little.

Sheet Metal Forming processes are as follows:

• Sheet metal Bending

• Sheet metal curling

• Sheet metal decambering

• Sheet metal expanding

• Deep Drawing

• Hydroforming

• Incremental Sheet Forming

• Ironing

• Laser Cutting

• Photo chemical Machining

• Press Brake Forming

• Punching

• Rolling

• Wheeling

Introduction about project:

Sheet metal is a metal forming process through industrial process into thin, flat pieces. Here, I have created a Sheet Metal Box assembly of Various thickened parts. Box assembly contains 3 main parts.

1. Box (base part)

2. Box Lid

3. Hinge

To design this parts I have used NX sheet metal workbench. Design methodology I have used to design this is described below.

Design Methodology:

Description:

The sheet metal Box assembly has been done with the above flow chart process. While designing the default thickness, bend radius relief depth and relief width value are set to 1mm at the Menu → Preferences → Sheet Metal here you can change the Sheet Metal thickness whenever necessary.

The sketch is drawn in the XY plane and the tab command is used for creating the base of the part.

Explanation and Procedure:

1.Direct Sketch: We use its tools to create a base sketch. (for eg: Rectangle, Circle, Line, etc.)

2.Tab: This tool act as an extrude (i.e) 2D sketch to 3D sketch can be done.

Tab Creation:

1. XY Plane - Create a sketch by drawing a symmetric rectangle wrt X axis at origin. Exit the sketch mode.

2. Change the design Parameters as per requirement.

3. Use Tab feature to create a rectangular metal sheet.

3.Flange: Adds a flat flange at an angle to a planar face and adds a bend between the two.

Flange Creation:

1. Use Flange Feature and select appropriate edges to create flanges normal to XY & XZ Plane respectively.

4.Closed Corner: Closes a corner where two adjacent flanges meet by extending the bends and flanges.

Closed Corners creation:

1. Use Closed Corner and select bends of adjacent flanges to close the corners.

5.Flange Creation:

1. Use Flange Feature and select the edge of previously created flange.

2. Create one more flange using above flange edge.

6.Hem Flange Creation:

  1.Create an open type Hem flange by selecting edge of flange created in step 5. Do the same on the other edge too.     

7.Mirror body: This command is used to mirror the body created with respect to the plane selection.

Mirror Body creation:

1. Select the Created body and mirror it about YZ Plane.

8.Unite: Combines the volume of two or more solid bodies into a single body.

Unite creation:

1. Use the two bodies (Created & mirror body) to unite.

9.Dimple: The dimple feature can be placed on any flat face including flanges and will extend in the direction of the face. Dimple dies are designed to reduce the weight in sheet metal fabrications, while adding strength and rigidity.

Dimple Creation (Side face):

1. Select the Side face of the Box and Create a sketch in the shape of "X". Apply sketch fillets to the edges to round the corners and connecting edges.

2. Use Dimple feature to create a stamp on it.

Mirror the above created dimple about XZ Plane using Mirror feature.

Dimple Creation (Bottom face):

1. Select the Bottom face of the Box and Create a sketch using rectangle. Apply sketch fillets to the edges to round the corners.

2. Use Dimple feature to create a stamp on it.

10.Bead:

A Bead is a long, drawn out impression, which is impressed to increase stiffness in metal sheets or plates. It is also important that how the bead runs over the work piece.

Bead Creation (Bottom face):

1. Select the Bottom face of the Box and Create a sketch using Circle.

2. Use Bead feature to create a stamp on it.

Mirror the above created dimple about X & Y Axis using Mirror feature.

11.Hem Flange: Modifies the model by folding the edge of sheet metal flange over onto itself for the purpose of safe handling or to increase edge stiffness.

Hem Flange Creation (Top face):

1. Select the top edges and use Closed type Hem flange to fold the material.

12.Datum Plane: Creates a datum plane used to construct other features.

Lid Creation (Top face):

1. Create a Datum plane at an offset of 203mm from bottom face.

2. Now sketch on newly created plane using lines and arcs in such a way that it forms a lid shape.

3. Use Tab feature and select the sketch to create Lid.

4. Extend the edges of lid by using Flange feature.

13.Hinge Creation (Side face):

1. Create a Sketch on side face by drawing a rectangle. Exit the Sketch.

2. Create a Tab by selecting above sketch.

3. Use Break corners and select the bottom left edge to round it.

4. Create a flange at an angle by selecting edge of previously extruded Tab.

5. Now use Open loop type Hem. flange by selecting proper edge to create a fold.

6. Unbend the fold and created a sketch by drawing few rectangle. Exit the Sketch and do Normal cutout.

7. Re-bend the fold.

Now Mirror the Hinge about XZ Plane.

14.Hinge Creation (Top face):

1. Create a Sketch on top face by drawing a rectangle. Exit the Sketch.

2. Create a Tab by selecting above sketch.

3. Use Break corners and select the top left & right edges to round it.

4. Create a flange at an angle by selecting edge of previously extruded Tab.

5. Now use Open loop type Hem. flange by selecting proper edge to create a fold.

6. Unbend the fold and created a sketch by drawing few rectangle. Exit the Sketch and do Normal cutout.

7. Re-bend the fold.

Views:

1.Front view:

2.Top view:

3.Side view:

4.Isometric view:

Drafting:

We can create 2D drawing sheets in NX CAD from the sheet metal component designed. For that we have to follow the process below:

Application >> Drafting >> Base View >> In model view to use - FLAT PATTERN created >> Adjust appropriate scale >> Drawing Sheet formed >> Give Proper Dimensions.

Drawing sheet:

Detailed view:

CONCLUSION:

• Finally the box assembly of the sheet metal is designed on the Siemens NX12.0

• The tools and features used for the box assembly is learned.