Sheet Metal Box Assembly design Using Siemens NX

SHEET METAL BOX ASSEMBLY DESIGNING USING SIEMENS NX

OBJECTIVE

To Create a Sheet Metal Box Assembly design using Siemen NX cad software for improving Sheet Metal designing skill

INTRODUCTION

Sheet metal is one of the most versatile materials in the manufacturing industry. It’s made from steel, aluminum, brass, copper, tin, nickel, titanium, or precious metals. It ranges in thickness from wispy leaf through light foil to heavy plate. It takes a variety of forms: plain flat sheets, embossed, etched, ribbed, corrugated, and perforated. And its uses expand across many different industries including transportation, aerospace, appliance manufacturing, consumer electronics, industrial furniture, machinery, and more.

Sheet metal components can have deceptively complex manufacturing processes and the design process itself can be similarly tricky. CAD softwares such as Siemens NX cad ,SOLIDWORKS etc. are used to design the complex Sheet Metal components .

Sheet metal design software considers the fabrication methods needed for manufacturing. As you create flanges and add bends, the sheet metal design software will accurately represent the flat pattern required. The flat pattern can be used to document and manufacture associatively as the design changes.

Here in this project we are dealing with the Sheet metal Box Assembly designing using the software Siemens NX cad

DESIGN METHODOLOGY

Here the metal box is created in a single part document as different Bodies. The box consist of different bodies like the box , the lid and the hinges . This box design consists of Repeated features like cut-outs, bends, flanges, holes, dimples, and beads. Every feature is designed in an order following the industrial procedure to keep the design intent. The design methodology used for this project can be summarized as depicted in the flowchart below:

COMMANDS USED

• Sketch
• Tab
• Flange
• Hem Flange
• Break Corner
• Closed corner
• Unbend
• Normal Cut Out
• Dimple
• Bead
• Rebend
• Mirror Body/feature
• Unite
• Flat Pattern
• Draft

1) Sketch

Sketches are the basic element or we can say the foundation of a design model. A base sketch is needed to perform most of the operations in Sheet Metal designing including Tab , Dimple , Bead , Hole , Contour Flange etc. The sketches can be created using the various sketch tools provided top left corner of the interface

2) Tab

Normally tabs are the Basic feature in NX sheet metal designing process. Tab Command extrude a sketch along a vector by a thickness value or by adding material to existing face and bend regions of a sheet metal part

3)Flange

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 the material added.

4) Hem Flange

Hemming is a sheet metal forming operation in which the edge of the sheet is folded back on itself. It serves several purposes: to fasten two sheet metal parts, to improve the appearance of edges (remove burrs and rough edges) and to increase the part stiffness.

5) Mirror Body

Mirror 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

6) Unite

After the mirror of the body is completed, it results in two separate bodies which is not the intended one. Unite allows us to combine the bodies and make one single body. After applying the Unite feature, the black edge on the face disappears.

7) Break Corner

The command used to break or round the corners in a solid body in order to avoid accidents by the sharp edges

8) Closed Corner

The command use to close the corners in between two flanges or bends is the closed corner feature.

9) Unbend

Use the Unbend tool to unbend one or more curved surfaces such as Bends or Curved walls to a flat configuration in a Sheet Metal part .For performing a Unbend feature its must to define a fixed planar face or edge. We can either select bend geometry individually or automatically select all the bend geometry.

10) Normal Cut Out

Normal Cutout command extract volumes from sheet metal by using sheet metal production principles. Cutting faces will be perpendicular to the sheet metal surface

11) Dimple

Use this command to create a raised dimple feature in a sheet metal part. The dimples can be placed on any flat face including flanges and will extend in the direction of the face. The dimple feature will be governed by the settings defined in the Options Form. Dimple also helps the sheet meatal part to increase its stiffness

12) Bead

Beads are the features added in sheet metal components in order to increase the stiffness of the 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, four small beads are applied in the symmetric positions as shown in the image below.

13) Rebend

Command use to re bend the un bended parts along with the feature applied after the Unbend. After addition sketches and features the sheet metal is to be re bended to its required shape. This operation is done by box selecting all the features and clicking the ReBend command.

14) Flat Pattern

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

15) Draft

After the modelling ,the manufacturing of the component a technical 2D drawing of the component with accurate dimensions or scales denoted. For achieving this we are using the command Draft.

PROCEDURE

The Box assembly is created as different bodies such as

• Box
• Lid
• Hinge 1
• Hinge 2

Box

• Create a Base sketch and Perform the Tab feature with 1 mm thickness

• Create Flanges from the two edges with 200mm length and 10 mm bend radius as given in the picture

• Create another 2 Flanges from the edge of the previously created flanges with 70mm length and same 10 mm radius .

• Close the two corners using the Closed corner Set the type to corner and Relief

• Create 2 Flanges one over the other on the edge shown in picture. Apply specified length and bend radius

• Do the same operation on the opposite edge

• Create two Hem flanges on the edges of the previously created Flanges with 5 mm length and 0.5 degree bend radius. Set the Flange type to open

• Mirror the Body about the YZ plane and ensure all the option in the feature menu is ticked.

• Unite the mirrored parts in to one

• Using proper sketch create a Dimple with 1mm depth on the side face of the box

• Mirror it to the opposite side

• Create another Dimple on the bottom side with 1 mm depth using a slot sketch od 350 mm length , 30 mm width,10 mm radius

• Using a 15 mm radius circle create a Bead on one bottom corner and mirror it to all the other three corners

• Unbend and Rebend the body

• Apply Hem Flanges on the top outer edges of the box as shown in the figure with 2mm length

Lid

• Crete a Datum plane with 203 mm away from the origin ,linear to XY plane

• Create the Sketch of the Lid by converting the upper edges of the Box and Create a Tab with 2 mm thickness

• Then Create two Flanges on the two edges of the lid with a length of 3 mm as shown

Hinge 1

• Create a Tab using a rectangle sketch of 55mm length and 20mm width on the right side face of the Box

• Break the corner with 10 mm radius using Break corner command

• Create 2 Flanges with 4 mm length and an angle of 40 degree as shown in the figure.

• Create a open loop type Hem flange on the edge of the newly created flange with a sweep angle 325 degree and bend radius 5 degree

• Unbend the body and perform a normal cut out with the given sketch

• Rebend the Body and mirror the body to opposite side

Hinge 2

• Create a new Tab on the top surface of the lid using a rectangle sketch as shown in figure

• A Flange of 5 mm length and 43.5 degree angle is created on the edge of the newly created tab as in the picture

• Create a open loop type Hem Flange of 325 degree sweep angle and 55 mm bend radius.

• Unbend the Body and do a Normal cutout using the proper sketch

• Rebend the body back to its required shape

The modelling of Box assembly is completed here. The different view are given below.

Now apply suitable color to the model for a better look

Flat pattern of each bodies are below

1) Box

2) Lid

3) Hinge 1

4) Hinge 2

Drafted images

Box

Lid

Hinges

Conclusion

The Box Assembly is Designed perfectly with an awesome appearance