Advanced Sheet Metal Design Using NX Cad Challenge Odd Shaped Enclosure

ODD SHAPED ENCLOSURE

OBJECTIVE :- To design an odd shaped enclosure and create a draft of it using Siemens NX Sheet metal application.

INTRODUCTION :-

Sheet metal is metal 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. Countless everyday objects are fabricated from sheet metal. Thicknesses can vary significantly; extremely thin sheets are considered foil or leaf, and pieces thicker than 6 mm (0.25 in) are considered plate steel or "structural steel".

Sheet metal is available in flat pieces or coiled strips. The coils are formed by running a continuous sheet of metal through a roll sitter.

NX CAD Sheet Metal Module - Creating fast, accurate flat patterns is the goal of any organization that manufactures products which contain sheet metal parts. NX Sheet Metal provides a set of tools within the NX design environment that allows for simple and fast design of sheet metal parts, dependent on their material and manufacturing process, the most common of which is straight brake sheet metal forming.
With NX Sheet Metal, formed and unformed representations of the parts are created closely following the industry workflows and best practices for bending calculations, tooling, and sheet metal features. The value lies in improving quality and reducing cost of sheet metal parts by producing an accurate sheet metal pattern as the correct input for part manufacture, whether internally or to a supplier.

This project is to create the enclosure, by creating the solid model and wraping the sheet metal over the solid surface. Then we need to add the features in the wrapped sheet metal.To add more features like Dimple, Louver, Beads then the sheet metal has to be unbend. Finally flat pattern has to be created to check the manufacturing fesability of that product.

DESIGN METHODOLOGY

Design methodology is explained by the flow chart as follows :

Features Used In the Modelling :-

The software used to design this component is NX-CAD also called as Unigraphics. We are exploring the Sheet metal Module of NX CAD in this project. Some of the commonly used features through this modelling are explained as below.

• Sketch - It is the basic of any design.
• Extrude - It creates a feature by extruding a section along a vector.
• Sheet Metal from solid - It builds a sheet metal model that takes its shapes from a collection of planar faces. This command is used to convert the solid body into a sheet metal body. After selecting the command and the solid body, we can also remove the edge sharpness by removing the material at these places.
• Tab - Tab is a command used to create a base for any sheet metal part that can be extruded from a sketch. The sketching plane can be selected as per the designer’s choice.
• Flange - It is used to create an extended part (bend) of a sheet metal. It is created at the edge of one side of the model. This command will allow us to select the edge of the base to create a projecting flat extruded surface. The angle, width, length, and type of flange can be determined as per the requirements.
• Jog - It modifies the model by lifting material on one side of a sketch line, adding a flange between the two sides. Jog is created at another end of the model opposite to the flange. Jog is a command to lift off one whole side of the part. By selecting a line and the plane, the material can be pushed down or lifted off depending on the situation.
• Unbend - This feature is used to unbend the adjacent bends and flatten them. Here it is used to create more features. This command is used to unbend the sheet metal parts to create geometries and work on complicated designs. In this command, we have to select a stationary face and then select the corners of flanges to unbend.
• Rebend - It is used to rebend the corners that were bent before along with any features added after the unbend feature.
• Bead - It lifts material along the contour of a sketch that simulates a stamping tool, it is used for giving strength to the sheet metal. Here two beads are created on the unbent surface. The selected sketch is lifted off from the base to provide strength to the material. Similar to dimple, the material can be removed in both directions.
• Hole - It adds a hole to one or more solid bodies in a part or an asembly with options for counterbored, countersunk and threaded. Here six simple holes are created on the unbent surface with a diameter of 10mm. It can be used to make customized or standardized holes along with a defined point or path. The dept of the hole can be controlled.
• Flat pattern - It creates a flat pattern feature from the formed sheet metal part. The user chooses this command to create a flat view of the sheet metal after unbending all the sides and faces. This view can be used in drawing the flat pattern along with the bend radius and other dimensions.

Steps Followed during modelling :-

Step-1 : Creating the solid body

The sketch for the solid body has to be created. Then the sketch is to be extruded using Extrude command which is avaliable in the modelling workbench.

Step 2: Extrusion of the skectch

The sketch is extruded upto 200mm. Thus the solid body is ready to wrap up with the sheet metal over the surface. By wraping the sheet metal we can get the solid shape profile in the sheet metal.

Step 3: Wrap the solid body

The solid body is now wrapped with the sheet metal using the command Sheet metal from the solid. This command helps in building a sheet metal model that takes its shape from a collection of plannar surface.

Step 4: Adding Features

The features like flange is added at the edge of the sheet metal. Jog Feature is added by creating a sketch on the face of the sheet metal. Then the jog command is used with the required height to make the feature.

Step 5: Unbend

The sheet metal is unbend using unbend command. This is done to add a features like dimple, bead in the bending region.

Step 6: Creating Bead

For creating the Bead, sketch profile is created on the face of the sheet metal and the bead command is used with the requires depth value. Then the feature is mirrored using the mirror feature command.

Step 7: Hole creation

The hole is created, using hole feature command. Here the position of the hle is created and the diameter is mentioned as per the requirement.

Step 8: Rebend

After creating all the required features, then the model is to be Rebend. This enable us to check the manufacturability of the product without any interference while bending

Step 9: Flat pattern

This option is to create the flat pattern feature from the formed sheet metal part. This finally gives the whole sheet metal part with the added feature which helps us in the manufacturing process.

Conclusions :-

The sheet metal design of an odd-shaped enclosure was completed using the basic commands such as Tab, Flange, Sheet Metal from solid, Jog, Hole, Unbend, Bead, Flat pattern, and Bend table. These basic commands have influenced the designer to maintain geometric constraints and achieve the final product.

Some collections of Model: