Advanced Sheet Metal Design Using NX Cad Challenge_5_Odd Shaped Enclosure

INTRODUCTION

In this project we will learn the step by step procedure to design a ‘Sheet metal Box Assembly’ using “Siemens NX Sheet Metal Application”.

Let’s see how the casing part is built with a flowchart of features involved in the drawing and then discuss the features and their uses and at last see how everything is blended together to deliver this phenomenal product.

FEATURES USED:

• Sketch: The sketch is the fundamental base element for any feature in the design of any sheet metal component. Most of the features require a sketch. The very first step is to sketch which is then used to create a tab or the base feature. So, the first sketch can be called a base sketch. For other features which are the children features of the tab, the sketch may require again on a particular plane or a face.
• Bend: Bend feature is added wherever a bend in the sheet metal component is required. It may be at any position or at any angle. A sketch is required to create a bend. It can be an open profile and it can be either a straight line or a curve. For this project of casing design, two straight lines symmetric with respect to X-axis are drawn for the bending curve.
• Flange: The flange is an additional face created automatically from any edge of the existing sheet metal component. It is additional material connected to any face or edge which is bent from the respective edge or face. It can be at any position or at any angle. For this casing design, four simple flanges are created with the material inside the edge of the existing component.
• Break Corner: This feature breaks the sharp edges in the corners and makes it round or adds chamfer. It is like the fillet feature in some other CAD software. It prevents the fracture breaking of the sharp corners.
• Unbend: This is a very powerful and very useful tool in Siemens NX. It allows all the bends made by the various features to the unbent state at once. In order to achieve a flat configuration of the sheet metal as per the design intent, it is necessary to choose the bends in order. It is also possible to box select all the bends at once. Once the unbend feature is used, further features can be carried out using the sketches created in the unbent state.
• Hole: Hole feature in sheet metal design workbench is just like in the model workbench. It can create either simple or counter bore or countersink or tapped holes. For this casing, first, the four points are sketched symmetric to the x-axis in position and the hole feature is applied.
• Dimple: Dimples in sheet metal components provide more strength and rigidity to the flat structure of the component. Dimple feature in Siemens NX is created using the sketch created in any face or any flange of the sheet metal component. For this casing design project, a dimple made up of a 16 points curve is used at the center of the component.
• Beads: Beads are the features added in sheet metal components in order to increase the stiffness of the component. Beads require a sketch in order to apply the feature. It can be either an open or closed profile. For this casing design project, four small beads are applied in the symmetric positions as shown in the image below.
• Re-bend: All the features added after the unbend feature are added in the unbend state itself. After the addition of sketches and additional features are completed, the sheet metal component has to be re-bent to the required position. This is done using the re-bend feature and selecting all the bends in order or by box selection. This completes the design process of the casing adding the features.
• Flat Pattern: Flat pattern is the representation of the entire sheet metal component in the 2D form of the flat sheet metal with all the bends, cut-outs, holes, and additional features in the form of lines or edges. The flat pattern ensures the ability to cut the sheet metal out of the raw sheet metal plate. It removes the possible errors such as interference or collision within the same component.
• Datum plane: It creates a datum plane used to construct other features. It is created to form the lid
• Datum coordinate system: It creates a datum coordinate system used to construct other features. It is created as a reference to mirror the bodies and the features.

DESCRIPTION OF THE DESING:

To create this design we start of sketching on the XZ-Plane, a trapezium like structure is made and extruded into a solid metal along y axis at length of 200mm. now this body is wrapped with sheet metal 3mm thick. After which the flanges bends and jogs are made on both the edges as required in our design. Now the sheet metal is unbend along the horizontal face and a sketch is made in the top face of the design to form some beads, dimple and holes. The metal is then re-bent and the structure is ready. To see the outline of the structure we make the flat pattern.