Advanced Sheet Metal Design Using NX Cad Challenge_2_Box Assembly

Advanced Sheet Metal Designingof Box Assembly in NX CAD

Objective:

To design a model of sheet metal box assembly using the sheet metal design tools application in Siemens NX CAD Software.

Introduction:

Sheet metal forming can be used in different industrial areas. Various computer-controlled manufacturing processes are used. These manufacturing processes are optimally adapted to the different materials, material thicknesses and other important factors.

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 6mm (0.25in) are considered plate steel or “structural steel”

Sheet metal is used in automobile and truck (lorry) bodies, airplane fuselages and wings, medical tables, roofs for buildings (architecture), and many other applications.

Sheet metal forming is suitable for almost all manufacturing industries: The automotive industry uses it to produce heavy-duty body parts such as fenders, hoods and vehicle doors. The food industry uses cans that are made with the help of forming technology. It can also be used to manufacture components such as wings and propellers for the aerospace industry. Suppliers of household appliances also benefit from the various sheet metal forming processes. They use the finished sheet metal parts in their kitchen hoods, sinks and freezers. In addition, sheet metal forming is used in apparatus construction, plant construction, electrical, pharmaceutical, medical, measurement and control technology, among others. Ventilation, air conditioning and communications technology also use these methods.

There are many different metals that can be made into sheet metal, such as aluminium, brass, copper, steel, tin, nickel and titanium. For decorative uses, some important sheet metals include silver, gold, and platinum (platinum sheet metal is also utilized as a catalyst).

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.

As the name suggests, straight brake sheet metal forming uses manufacturing tooling (press brakes) that form the part by bending the metal blanks along linear or straight lines. This is an efficient and cost-effective way to create simple brackets, housings, and enclosures across many industries.

A brake is a metal working machine that allows the bending of sheet metal. A cornice brake only allows for simple bends and creases, while box and pan brake also allow one to form box and pan shapes. It is also known as a bending machine or bending brake or in Britain as a sheet metal folder or just a folder.

(Fig.) Manually driven bending brake

(Fig.) Cornice brake

(Fig.) Hydraulic press

(Fig.) Sheet metal bending in press brake

Brakes come in sizes suitable for light aluminium or brass for small boxes and operated by hand, up to industrial sixed and counterweighted hand-operated or hydraulic machines suitable for large sheets of steel.

With Siemens 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.

In this project we are going to design a model of sheet metal Box assembly in Siemens Nx CAD software.

Design Methodology:

(fig.)Design methodology of sheet metal box assembly

Tools and Features used while Designing:

Sheet Metal application tools are mainly used in designing the model of box assembly.

Let’s have a look at the tools and features used in designing the box assembly.

The following features are found under home tab in sheetmetal application workbench in NX CAD.

Tab:

This feature creates a base feature by extruding a sketch along a vector by a thickness value, or adds material to a planar face. Additional planar selections can be added to generate bends as part of the base feature.

Normal Cutout:

This feature cuts material by projecting a sketch onto the model and then cutting perpendicular to the faces intersected by the projection.

Bend:

This feature modifies the model by bending material on one side of a sketch line, adding a bend between the two sides.

Flange:

This feature adds a flat flange at an angle to a planar face and adds a bend between the two.

Break Corners:

This feature rounds or chamfers a sharp corner of a tab or flange.

Unbend:

This feature flattens a bend and the material adjacent to the bend.

Dimple:

This feature lifts an area of the model inside a sketch that simulates a stamping tool.

Bead:

This feature lifts material along the contour of a sketch that simulates a stamping tool.

Rebend:

This feature restores an unbend feature to its previous bend state, along with any features added after the unbend feature.

Hem Flange:

This feature modifies the model by folding the edge of a sheet metal flange over onto itself for the purpose of safe handling or to increase the edge stiffness.

Closed Corners:

This feature closes a corner where two adjacent flanges meet by extending the bends and flanges.

Mirror feature and Mirror Body:

Mirror feature toolcopies a feature and mirrors it across a plane

Mirror Bodytoolcopies a body and mirrors it across a plane.

Unite:

This feature combines the volume of two or more solid bodies into a single body.

Steps involved:

• First a sketch of rectangle is made in Datum Coordinate plane and dimensioned as required.
• All Global parameters of the part properties are changed to 1mm in Sheetmetal preferences.
• Extrude the rectangle sketch using tab feature.
• This will be our base bottom for our model.

• Add some flat flanges to the adjacent sides from the base rectangle edges using Flange feature at desired parameters.

• Use closed corner tool to close the corners with adjacent flanges.

• Use the flange, hem flange tools to fold and stiffen the edges at the middle.

• After modeling the half part of the model, use mirror body tool and then unite tool to make a mirror copy of the designed part and combining it as a single part.

• For some special emboss and extrude of shapes, use the dimple tool which creates an emboss in the model w.r.t a sketch.
• Mirror the dimple feature to the other side with mirror feature tool.

• Unbend the model using unbend tool to get a flattened sheet metal shape of our model and check how it looks as a plain sheet metal and then re bend it back using rebend tool.

• Add resting beads to our model using bead tool and mirror it using mirror feature tool.

• Add some fine edges and stiffen the upper part of the model using hem flange feature.

• Create cap part using tab feature w.r.t to a rectangle sketch at a new datum plane that rests at the upper part of our model.

• Add flanges to the corners of the cap.

• Create a sketch a rectangle and extrude using tab feature for the base of side clips at adjacent sides of our model.

• Use break corner tool to round the edge and add some flanges and hem flange to the clips.
• Unbend the clip part and use normal cutout tool w.r.t to a sketch and mirror it using mirror feature.

• Create a rectangle sketch on the top of cap part for another clip and extrude it using tab and the follow the similar steps used for previous clip with different sketch for normal cutout.

You can add colors to the model using Object Color option from Menu->Edit->Object Color.

Final model:

Box Assembly in True shading visualization:

Standard Views of Sheet metal Box Assembly model:

Front View:

Side View:

Top View:

Isometric View:

Conclusion:

A Sheet metal Box assembly model is successfully designed in Siemens NX Cad Software using Sheet metal application tools.