Advanced Sheet Metal Design Using NX Cad Challenge_6_Bracket

Project Title : Sheet Metal design of bracket using NX CAD

Objective : 

To create a bracket using advanced sheet metal tools in NX CAD. 

Introduction : 

What is Sheet Metal - 

The sheet metal is formed by an industrial process into thin, flat pieces. Sheet metal is one of the fundamental forms used in metal working, and it can be cut and bent into a variety of shapes. The metals which are less 6 mm thickness are considered as sheet metals. The sheet metal is available in flat pieces or coiled strips. 

Following are the 9 different types of sheet metal operations:

1. Shearing Operations
2. Blanking Operations
3. Punching Operations
4. Piercing Operations
5. Trimming Operations
6. Drawing Operations
7. Embossing Operations
8. Bending Operations
9. Squeezing Operations

1. Shearing

It is a cut in a straight line across a strip, sheet or bar. It leaves a lean edge on the piece of metal is sheared or cut. In this operation, a sheet metal workpiece is placed or kept between two dies from one end. And, the punch is hit at the other end of the sheet, producing a shearing effect.

It has 3 basic stages:

1. Plastic deformation
2. Fracture
3. Shear

a) Plastic Deformation

When a metal is placed between the upper and lower blades of the shear and pressure is applied, plastic deformation takes place. It extends into metal for about 5 to 40% of metal thickness.

b) Fracture

At the point of greatest stress concentration fracture takes place.

c) Shear

Small fractures are found and the metal is sheared.

2. Blanking

It is an operation of cutting a whole piece from sheet metal. In which enough scrap is left all around as shown in fig. A punch and die is applied for this type of sheet metal operation.

3. Punching

It is an operation of producing circular holes on a sheet of metal by a punch and die. This is the exact opposite of blanking but the operation is nearly the same. A Punch and die are further used here such as blanking operations.

4. Piercing

Piercing is the process in which desired shape holes are produced in a piece of sheet metal without eliminating any material from the sheet or removing a very small amount of material as shown in the figure. Both punch and die are also applied in this operation. The punch used in the piercing operation is usually bullet-shaped.

5. Trimming

The trimming operation is also known as shaving operation. It is a finishing operation by removing the burrs from the cut edges is taken out in order to make edges smooth and also provide dimensional accuracy.

6. Drawing

It is an operation of producing thin-walled hallows or vessel shaped parts from sheet metal. It can be divided into two categories:

1. Deep drawing
2. Shallow drawing

a) Deep Drawing

The length of depth of the object to be drawn is deeper than its width.

b) Shallow Drawing

The length of the object to be drawn is less than its width. The examples of drawing are pans, tubes and cams.

7. Embossing

It is the metalworking operation which is used to create raised surfaces or lettering in sheet metal. There is no change in metal thickness during this operation.

8. Bending

It occurs when forces are applied to localized areas. Here the metal flow is uniform along the bend axis with the inner surface in compression and outer surface in tension.

Types of bending

1. Edge bending
2. V-bending
3. U-bending
4. Offset bending
5. Channel bending

1. Edge Bending

It is a type of bending operation, In which a piece of sheet metal is fixed or held between two dies from one end, as shown in the fig. Then the other end is forced to strike upon the punch which is free or unfixed. Thus, the free or unfixed edge of the sheet metal piece is bent to make the forming process.

2. V-bending

In these type of bending operation, when a piece of sheet metal is pressed between the die and the punch; It is formed into a V-shape in the die.

3. U-bending

In this type of a bending operation, in which when the punch is pressed by a force to move into the die, the sheet metal piece gets formed into a U-shape.

4. Offset Bending

It is a type of bending operation, in which a piece of sheet metal is formed into an offset shape with the help of a punch and die.

5. Channel Bending

In this type of a bending operation, in which when a force is used to the punch to move into the die, the sheet metal piece, in between the punch and die, gets the shape according to the shape of the die and punch i.e. a channel shape.

9. Squeezing

It is a quick and widely used way of forming ductile metals. It has different operations such as sizing, coining, riveting etc.

1. Sizing

Sizing operation is a squeezing operation that reduces the thickness of the metal. The sizing is done in an open die and only the surface where the die and workpiece touch will be sized.

2. Coining

It is a process of pressing metal in a die so that it flows into the die space. For example Medals, Coins, and Jewellery.

NX CAD in sheet metal -

NX sheet metal design software incorporates material and process information in sheet metal-specific modeling features: bends, flanges, tabs, cutouts, beads, dimples, louvers, corner and edge treatments, patterns and other formable features. You can also quickly convert solid models to sheet metal components, and create sheet metal parts that enclose other components.

NX Sheet Metal-specific features such as flanges, tabs, jogs, corner conditions, and drawn cutouts & many more along with productivity enhancements such as – automatic bend reliefs.

The software also provides common modeling features typically used in sheet metal design, such as holes and slots, as well as other essential capabilities such as copy, paste, and mirror.

The application provides defaults for sheet-metal-specific properties such as material – thickness, bend radius, and bend relief. You can easily change these defaults.

 Design methodology /Flow Chart : 

Description : 

Create the base sketch from reference to the given bracket sketch. Create the sketch profile as shown in the below picture

By using contour flange, create the base to a length of 200 mm

Create a sketch on top plane as shown in figure

Create the normal cut out from the drawn profile

Smoothen the sharp corners using break corner option with a radius values of 25 mm

Break corner using radius 30 mm

Break corner using 60 mm radius

Create sketch for bead

Unbend the bracket 

Create bead form the profile created

Rebend the bracket

Local radius

Create a point on top view to locate the holes

Create the holes using hole command

Measure distance

Views : 

Isometric view

Front view

Side view

Top view

Drawing sheet : 

Feature tree : 

Conclusion : 

To understand the different sheet metal operation using NX CAD