Advanced Sheet Metal Design Using NX Cad Challenge_2_Box Assembly

ADVANCED SHEET METAL DESIGN OF BOX ASSEMBLY USING SIEMENS NX CAD

OBJECTIVE:

• To design a sheet metal box assembly using Siemens NX Cad.
• To create a drafting of the same part in A4 sheet.

INTRODUCTION:

Sheet metal is a metal formed by an industrial process into thin, flat pieces. Sheet metal can be cut and bent into a variety of shapes. Countless everyday objects are fabricated from sheet metal.

NX formerly known as "unigraphics", is an advanced high-end CAD/CAM/CAE software. NX Sheet Metal provides a set of tools within the NX design environment that allows for simple and fast design of sheet metal parts.

DESIGN METHODOLOGY

Design methodology is explained by the flow chart as follows:

DESCRIPTION

Sketch:- It is the basic of any design.

Tab:- It is used to create base feature of a sheet metal by extruding a sketch along a vector by a thickness value. Here tabs were created as the base of the top and bottom hinges as well as the base of the box.

Flange:- It is used to create an extended part (bend) of a sheet metal. There are total twelve flanges created in the box assembly.

Unbend:- This feature is used to unbend the adjacent bends and flatten them. Here it is used to create cut outs for the hinges.

Rebend:- It is used to rebend the corners that were bent before along with any features added after the unbend feature.

Dimple:- It lifts an area of the model inside a sketch that simulates a stamping tool. Here three dimples are created,i.e., in the middle of the base and two at the sides of the box.

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. There are total four beads created around the dimple at the base.

Normal cutout:- It cuts the material by projecting a sketch onto the model and then cutting perpendicular to the faces intersected by the projection. Here a rectangular shaped cutout was created to create the top and bottom hinges.

Mirror feature:- It copies a feature and mirrors it across a plane. Here the dimple on the side wall and beads on the bottom of the tab are created using this feature.

Hem flange:- It modifies the model by folding the edge of a sheet metal flange over onto itself for the purpose of safe handling or to increase edge stiffness. It is used to create flanges on the walls of the box, on the sides of the lid and also on the hinges.

Break corner:- It rounds or chamfers a sharp corner of a tab or flange. It is used in the tab created for hinge.

Closed corner:- It closes a corner where two adjacent flanges meet by extending the bends and flanges. It is used to close the gap between the flanges used to create the walls of the box.

Mirror body:- It copies a body and mirrors it across a plane. Box, lid and hinges are mirrored as a body using this command.

Unite:- It combines the volume of two or more bodies into a single body. Two box and lid parts are combined using this feature to create a single body.

Flat pattern:- It creates a flat pattern feature from the formed sheet metal part. Separate flat patterns are created for the box, lid and the hinges.

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.

Order of Usage of tools:

• The sheet metal preferences are set as required.
• A required sketch is drawn in the XY plane.
• The base part is created using the TAB command.
• FLANGES are added to the edges of tab.
• CLOSED CORNER tool is used to close the space in the corners between the flange and the tab.
• FLANGES and HEM FLANGES are added as required.
• The body of the box is then mirrored using MIRROR tool.
• The UNITE tool is used to combine the two mirrored bodies as a single body.
• DIMPLE is created at a side of the box assembly and is then mirrored to the other side.
• FLANGES are added to the edges of tab.
• DIMPLE is also created at the bottom of the box assembly.
• UNBEND tool is used to unbend the whole sheet metal and BEAD is added at the bottom of the box assembly as a lower support.
• The sheet metal is again rebended using REBEND tool.
• New datum plane is created to create the lid.
• The lid for the box is created using the TAB tool.
• The extension of the lid holding the box together is created using FLANGE tool.
• The lid holder is create using TAB, FLANGE, BREAK CORNER & HEM FLANGE tools.
• BEND tool is used to bend the sheet metal.
• Gaps in the holder joints are created using NORMAL CUTOUT tool.
• The sheet metal is then again rebended using REBEND tool.
• Finally, the FLAT PATTERN tool is used to create a 2D representation of the flattened 3D sheet metal part

IMAGES

Following are the images of box assembly in different views:

flat pattern

sheets