Sheet Metal Bracket Design using Siemens NX
Title: Sheet Metal Bracket Design using Siemens NX
OBJECTIVE: To apply the Sheet Metal design process and to design a Sheet Metal bracket in parametric CAD software Siemens NX following industrial workflow.
INTRODUCTION:
Sheet Metal is a metal with a small thickness ranging from 0.5-6mm which is made thin and flat by rolling or hammering process. A number of mechanical components are made up of Sheet Metal. Sheet metal is widely used in the manufacturing industry due to its various advantages.
In this project, a bracket is designed in Siemens NX CAD software following the industrial approach. The use of a parametric modelling environment is the main use made in this project. This project focuses on the stiffening process of a bracket.
DESIGN METHODOLOGY:
The bracket designed for this project consists of features like contour flange, holes, 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:
DESCRIPTION:
Sketch for contour flange:
A contour flange can be created from any open curve. For this bracket, the sketch is created in an XZ plane with the following dimensions.
Contour Flange:
The contour flange is a flange created using the open sketch created in a plane. It is different from regular flange because it can be created in any shape and it does not require choosing the edge of any tab or existing flange. It can be at any position or at any angle. For this bracket design, a contour flange is created using the earlier sketch as the curve.
Normal Cut-out:
A sketch is created on the XY plane to cut away the unnecessary material. Then the operation normal cut out is carried out. It cuts away the material at the right angle with respect to the sketch plane.
Break Corner:
Break corner feature allows you to round off the sharp corners and remove the pointed corners. This is like a fillet feature in other CAD software. It is used to eliminate possible accidents due to sharp ends or to eliminate possible failures and crack propagation.
Sketch for Bead Creation:
For this bracket, a straight line is sketched first before applying the unbend feature. A straight line on the XY plane is drawn for this purpose.
Unbend:
This is a very powerful and very useful tool in Siemens NX. It allows all the bends made by the various features to the unbent state at once. In order to achieve a flat configuration of the sheet metal as per the design intent, it is necessary to choose the bends in order. It is also possible to box select all the bends at once. Once the unbend feature is used, further features can be carried out using the sketches created in the unbent state.
Bead Creation:
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 bracket, the bead is created selecting the line drawn in the earlier step with a radius of 7 mm.
Holes:
The hole feature in sheet metal is similar in solid modelling. Here, three general holes of a 20 mm radius are created while in the unbent state.
Rebend:
All the features added after the unbend feature are added in the unbend state itself. After the addition of sketches and additional features are completed, the sheet metal component has to be rebent to the required position. This is done using the rebend feature and selecting all the bends in order or by box selection.
Local Radius Analysis:
In NX, the radius value of the parts and models can be easily measured or analyzed by using the local radius tool under the tab ‘Analysis’. Here, the local radius of the bead and the bend radius is measured and shown.
Measure Distance:
This tool allows measuring distance between any two references in the part within NX. In this bracket, the distance between the two holes is measured and shown.
The finished model with the feature navigator is shown below:
Flat Pattern:
Flat pattern is the representation of the entire sheet metal component in the 2D form of the flat sheet metal 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.
Drafting:
After the design is complete, the execution or the manufacturing of the component requires a technical drawing of the component with the provided scale and with accuracy. The necessary details such as annotations, callouts, bend tables can be added as per the requirement. For this bracket design project, a drawing is created out of the flat pattern in a 1:2 scale in an A4 sheet, and an additional drawing showing different views is also shown.
DIFFERENT VIEWS OF THE FINISHED MODEL:
FRONT VIEW:
SIDE VIEW:
TOP VIEW:
ISOMETRIC VIEW:
CONCLUSION:
In this project, a Sheet Metal enclosure having an odd shape is successfully designed from a solid body in the sheet metal workbench of Siemens NX. The advantage of a parametric modelling environment is used to maintain our desired design intent and all the necessary features are applied in order following the industrial workflow.