Advanced Sheet Metal Design Using NX Cad Challenge_2_Box Assembly

SHEET METAL BOX ASSEMBLY DESIGN

OBJECTIVE

To design a box with different parts and create the assembled model in the 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 methodology adopted for this box assembly design is an industrial oriented one. Each part are modeled with the design for manufacturing in mind. There are processes like normal cutout, unbent and rebent to to add the features on the design and check if it is manufacturable.

DESCRIPTION

• Sketch

For creating any sheet metal surface, we have to first make a sketch. A rectangular base sketch for creating the tab with 200 mm length and 150 mm width.Other than tab, various sketch are also made on different planes or faces for creating other different part during designing.

• Tab

Tab is the first parent feature in sheet metal designing using Siemens NX tool. All the other features are usually based on tab. In this casing design, i created the tab by using the sketch on XY-plane.

• Flange

Flange is used to add extra material to the existing edges at any angle and of any size. For this project of box assembly design, i added four flanges on different edges, firstly i added two flanges with 200 mm length normal to the XY-plane and then another two flanges with length of 70 mm were added normal to XZ-plane.

• Closed Corner

Closed corner feature is used to close a corner where two adjacent flanges meet by extending the bends and flanges. For this box assembly we used the closed corner feature twise to close the open corners at the bottom side of the flange.

• Flanges for Hemming

For connecting the two flanges on side of box assembly we first created a flange without length and then another flange having dimension of 6.5 mm length with outside bend.

• Hem Flange

Hem flange feature is used to modify the model by folding the edge of a flange. The main pourpose of this feature is to increase the stiffness and for safe handling. For this box assembly i created the hem flange with 0.5 mm bend radius and length of 4 mm.

• Mirror Body

As of now half part of the box assembly was designed remaining half part was designed by using mirror body feature, which saves a lot of time. The plane selected is YZ-plane

• Unite

This feature is used to combine two different bodies which are in contact. The original and mirrored bodies are united with this feature.

• Dimple

Dimple is the feature that lifts the area of model inside the sketch that simulate a stamping tool. Generally, it helps to strengthen the flat structure. For this box assembly we first created an appropriate sketch and then i used dimple feature to create the final dimple on one side of box assembly. Same dimple was mirrored to the other side of box. One rectangular dimple was also added at the bottom of the box assembly for the purpose landing.

• Beads

Beads are similar feature like dimple, the only difference is that by using dimple we lift an area while in bead we lift the contour of the sketch. It also added to strengthen the component. For this project, one small bead was created near the top left corner having diameterof mm. The bead created is mirrored along XZ-plane and then with the YZ-plane to obtain the four beads on each corner.

• Unbend

Unbend feature is one of the most powerful feature in NX. In industry we have to mark all the marking and sketch on the flat sheet metal before it went to actual operation. So this unbend feature allows us to do that activity in Siemens NX software. For this project of box assembly design, we use this feature 2 times to mark the further operations.

• Normal Cutout

Normal cutout feature use to cut material by projecting a sketch onto the model and then removing material perpendicular to the faces intersecting by the projection. For this box assembly we used normal cut feature to remove two rectangular area which leads to forming the hinge barrels on both sides.

• Rebend

Rebent feature is used to restore the unbend feature to its previous bent state along with any feature added after the unbend feature. This is done by using rebent feature and selecting all the bends carefully in order they unbended.

• Flat Pattern

Flat pattern feature allows us to convert 3D sheet metal component into 2D form. By using this feature we can easily avoid error like interference or collision.

VIEWS

• Front View

• Side View (Left)

• Side View (Right)

• Top View

• Isometric View

DRAWING SHEET IMAGES

After designing 3D model for further process of manufacturing we have to convert the sheet metal box assembly into 2D sketch. The scale of the drafted views and flat pattern are 1:5.

• Flat Pattern

CONCLUSION

By using the proper design methodology and tools the sheet metal box assembly design has been completed using the Siemens NX software.