Advanced Sheet Metal Design Using NX Cad Challenge_2_Box Assembly

Objective:-

To design a Sheet Metal Box Assembly using Siemens NX Sheet metal application.

Introduction:-

• SIEMENS NX:- NX formerly known as "unigraphics", is an advanced high-end CAD/CAM/CAE, which has been owned since 2007 by Siemens PLM Software.
• SHEET METAL DESIGN:- NX Sheet Metal Design provides the design professional with a complete set of tools to efficiently create and manage sheet metal parts based on the knowledge of material properties and manufacturing processes. NX Sheet Metal Design tools incorporate material and bending information, enabling the model to represent both the formed component and flattened blank shapes

DESIGN METHODOLOGY

TOOLS USED

1.SKETCH :-

A Sketch is a named set of 2D curves and points located on a specified plane or path.You can apply rules, in the form of geometric and dimensional constraints, to establish the criteria your design needs.Features created from a sketch are associated with it, if the sketch changes so do the features

2.Datum plane:- It creates a datum plane used to construct other features. It is created to form the lid.

3.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

4.TAB :-

create a base feature by extruding a sketch along a vector by a thickness value, or by adding material to existing faces and bend regions of a sheet metal part

5.FLANGE:-

Flange command use to add a flat flange at an angle to a planar face and adds a blend between the two

1.Click flange command icon.

2. In the graphics window, select the edge to add a flat flange.

3. In the flange properties group.

• Select full option in the width option list.
• Set the length value in the length box. Click to change the direction if you want. In the length reference box, you can select more option as: inside, outside web, tangent.
• Select the angle of flat flange.
• In the inset box, you can select the method to inset material as: material inside, material outside, bend outside, material inside OML.
• Select the offset you want.

4. Click OK to finish this command.
Note: If you want to use a different bend radius value, you need to draw arcs in the section, or change the default bend radius value.

6.UNBEND:-

This feature is used to unbent the sheet metal taking any one face as a stationary face.

Flattens sheet model through selected bends.

To activate command:

• Click on command on (When sheet metal application activated.) “ Home => Form down arrow => Unbend”
• Activate command from “Menu => Insert => Form=> Unbend”

For Using “Unbend” command:

• Activate the “Unbend” command.
• Select the stationary face of the sheet metal.
• Select edges to bend

7.REBEND:- Rebends, the unbent feature of the sheet metal model.

It uses after the “Unbend” command If needed.

To activate command:

• Click command on (When sheet metal application activated.) “ Home => Form Gallery => Rebend”
• Activate command from “Menu => Insert => Form=> Rebend
• Select unbent faces on the model. (“Select Face” in the “Bend” tab highlighted automatically when command activated.)
• If you want to define stationary face on sheet metal model, click down arrow in the command window to open more options. Click on “Select Face or Edge“ in the “Stationery Face or Edge” tab in the command window. The function will be highlighted. Select stationary face on the model.
• Click the “Ok” to finish

8.DIMPLE:- The Dimple command to lift an area of the model inside a sketch that simulates a stamping tool. A Dimple feature across cylindrical bends in the unbent state. An open or closed section type of the Dimple feature can be created across a bend and a planar face, or completely inside the bend

9.BEAD:- Used for giving strength to the sheet metals

Bead command to lift material along the contour of a sketch that simulates a stamping tool. Beads can also be created to stiffen sheet metal parts.

• Choose Weld Assistant tab→Sealer group→Bead.

The Bead dialog box opens.

• In the Type group, Ellipse is selected.
• In the Primary Parts group, Select Face is active.
• Select a face on the primary part.
• In the Secondary Parts group, click Select Face and in the graphics window, select a face on the secondary part.
• In the Path group, click Select Curve or Point and in the graphics window select the curve you want to sweep the cross section along.
• In the Parameters group, set the parameters for defining the cross section.
• Click OK to create the Beadfeature

10.Hem Flange:- command to modify an edge of a sheet metal part by folding it onto itself for the purpose of safe handling or to increase edge stiffness.

The hem flange is always created as a secondary feature on a base part.

You can create hem flanges on:

• Linear edges and curved edges of the base part.
• Connected curves that include a curved edge. You can also create a flangeon the linear edge of such hem flanges.

In the following example, a flange is created on the linear edge of a hem flange, and then both flanges are flattened

11.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.

12.Normal Cutout:- Normal Cutout command to cut material by projecting a sketch onto the model and then cutting perpendicular to the faces intersected by the projection.

You can use planar sketches or 3D curves to specify the section for the normal cutout. If the sheet metal part has multiple bodies, you can specify the target body on which you want to create the normal cutout

13.Closed Corner:- Closed Corner command to modify two flanges in one operation and to close the corner where the two flanges meet. During flattening, the corner and relief geometry are made appropriate for a flat pattern.

When you use the Closed Corner command, you can create:

• Mitered closed corners on bends that have unequal bend radii or bend angles.
• Overlapping webs with mitered corners. This is applicable for the Close and Relief type of Closed Corner feature.
• Corners between flanges that bend in opposite directions.
• Corners between a wide range of corner angles.
• Mitered closed corners with a smooth transition from the miter to the cutout edges for the Circular Cutout , U Cutout , V Cutout , or Rectangular Cutout type of corner treatment options.

Description :-

Sketch for Base Tab:

For this box, a sketch for the tab is created in the XY plane first. The Constant Thickness of sheet metal base has been adjusted inthe Preferences Settings already to 1mm

• Firstly two flanges are made normal to the XY plane and then two other flanges are created normal to the XZ plane.
• The opening between two flanges or between the tab and flange which are perpendicular or at any angle. It should be adjacent to be able to apply the feature. It results in a closed part following the shape of the other part. For this box, a closed corer is used on both sides of the bottom of the flanges normal to the XZ plane.

• Create flanges For the fastening purpose by the bending of edges, a flange without length is first made and another bend flange is used to bend it outwards to obtain the following result.

• Then mirror the body feature allows the solid body to get copied and mirrored with respect to a plane. Here, the design made till this stage is a half part of the box which is then mirrored with respect to YZ plane. A black edge appears on the face of the side flange representing the separation between two bodies.after mirroring unite the two bodies using unite option

• A dimple is made on the face of one of the side flange. This dimple is then mirrored along the XZ plane to get the same feature on the other flange of the opposite side. After that mirror the feature using mirror feature optionas shown in the fig below

• At this stage, the hem flange is applied at the top edge of the side flanges, and the flanges normal to the YZ plane.

• create the lid for the box, a datum plane is created at a distance of 202 mm from the XY plane. The sketch is created taking the reference of the edges from the top view of the box design at this stage. Then the base tab is created with the sketch to create the lid. It will be a separate body in the box assembly design.

• A datum plane is created on the face of the flange perpendicular to the YZ plane and a rectangle is sketched to create a base tab.

• The unbend feature is used and the sketch is created on the face of the hem flange in the flat stage. Two rectangles are created as per the requirement for the hinge barrels of both sides. Then the operation normal cut out is carried out and then use the hem flange command select the open loop

• select the surface top of the lid sketch for the tab is created. Now, a base tab is added. This tab will be the base for the upper part of the same hinge. Here, the tab is a single part extended over the length.

• Similar to the earlier process, an open hem flange of radius 5 mm extended over a 325-degree angle is created.

DRAFTING SHEET

BOX ASSEMBLY IMAGES

FRONT VIEW

SIDE VIEW

TOP VIEW

ISOMETRIC VIEW

BOTTOM VIEW

CONCLUSION

By performing this challenge, I have learned how to use features like tab, flange, break corner, closed corner, dimple, hem flange, bead, rebend, datum plane, datum coordinate system (Datum CSYS), flat pattern, mirror feature, mirror body, unite, normal cutout and unbend by creating a box assembly