Challenge

Advanced Sheet Metal Design Using NX Cad Challenge_1_Casing Design

AAdarsh P A21 Feb 2022

SHEET METAL CASING DESIGN

OBJECTIVE

To model a casing using the sheet metal application in Siemens NX software.

INTRODUCTION

In this project we are going to learn about the different manufacturing processes that can be performed on a sheet metal. There is a factor known as the "K" factor which aids us in giving appropriate bend radius to the available sheet metal thickness. The K-factor comes from the ratio of the neutral radius divided by the thickness of the material on prepared charts and has a value between 0.3 and 0.5.

Sheet metal is metal formed by an industrial process into thin, flat pieces. Sheet metal is one of the fundamental forms used in metalworking, 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".

DESIGN METHODOLOGY

The sheet metal preferences are set before the creation of a 3D element. Here we gave a 1mm value for the four factors, material thivkness, rend radius, relief depth and relief width. The most important method we follow for the design of any sheet metal component is that, if we want to create holes, dimples, beads and cutouts, we need to first unbent the whole sheet metal model and make it a flat sheet and then do the required features and after all features are created the model is rebented to get its final design. This is done for ease of designing and to get a properly positioned features.

DESCRIPTION

Sketch

The primary step of creating a sheet metal part is to a surface on which we could perform the operations like flange, dimple, bead, cutout etc. So a tool known as tab is used to create this surface for creating the casing. For the creation of tab a closed sketch is needed. The sketch we are going to draw is a rectangle with a x-length of 60 mm and a y-width of 50 mm.

A tab is the base 3D structure that we use to create the whole design. Before producing the tab we need to first give global parameter values in the sheet metal section of the preferences tab. The value assigned is 1 mm.

Normal Cutout

It extracts material volume from sheet metal by using sheet metal production principles. Cutting faces will be perpendicular to the sheet metal surface. A cut of rectangle iis made with 40 mm length and 5 mm width.

Bend

It is a tool used to perform bends on a sheet metal. The input for the producing a bend is an edge. It produce bends on a straight or curved edge. Here we have to create two bends so we created the sketch which is two symmetric straight lines. Only one bend can be performed at a time. The angel is 90 deg for the bends.

Fange

A flange feature consists of a face and bend connected to an existing face along a straight edge. To add a flange feature, we select one or more edges, and specify the size and position of tthee material added. If there is material interuption where the flange is formed then material reliefs are automatically created.

Break Corner

It is used to round the sharp edges with user specific radius. The input parameters are the faces which connects the edges.

Unbend

One or more curved surface such as bends or curved walls to a flat configuration in a sheet metal part. For performing a unbent feature, it must define a fixed planar face or edge. We can select the curved surface of the bend as the input parameter.

Hole

Hole feature in sheet metal design workbench is just like in the model workbench. It can create either simple or counterbore or countersink or trpped hole. For this casing, first the four points are sketched symmetric to the x-axis in position and the hole feature is applied. The type of hole selected for this model is simple clearance hole and the screw size is M2.

Dimple

This feature uses closed sketch to rise or lower sheet metal surface which is similar to embossing in the manufacturing process. The demples can be placed on any flat face including flanges and will extend in the direction of the face. The dimple feature will be governeed by the settings defined in the options form. Dimple also helps the sheet metal part to increase its stiffness. We gave a a depth of 1 mm and rounting its edges with 1 mm punch radius.

Bead

Beads are the features added in sheet metal components in order to increase the stiffness of thee 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, one point is sketched on the flat surface and bead is created with the help of that sketch. The other three are mirrored for ease. The tool known as mirror feature is used.

Mirror Feature

It takes design features as in put and a mirror plane. Here two steps of mirror feature is performed, one with the yz-plane and the other with the xz-plane.

Rebend

This coommand is used to rebend the unbent sheet metal along with the features applied sfter the unbent. After addition sketches and features the sheet metal is to be rebented to its required shape. This operation is done by box selecting all the features and clicking the rebend command.

Flat Pattern

Flat pattern is the representation of the entire sheet metal component in the 2D form with all the bends, cutouts, 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 possibility errors such as interference or collision within the same component.