Advanced Sheet Metal Design Using NX Cad Challenge_5_Odd Shaped Enclosure
OBJECTIVE: The aim of this project is to create an Odd Shaped Enclosure using NX CAD Sheet Metal Application and create a detailed drawing for manufacturing.
INTRODUCTION:
Sheet Metal Fabrication is the process of forming parts from a metal sheet by punching, cutting, stamping, and bending.
3D CAD files are converted into machine code, which controls a machine to precisely cut and form the sheets into the final part.
Sheet metal parts are known for their durability, which makes them great for end use applications (e.g. chassis). Parts used for low volume prototypes, and high volume production runs are most cost-effective due to large initial setup and material costs.
Because parts are formed from a single sheet of metal, designs must maintain a uniform thickness. Hence the designer must be sure to follow the design requirements and tolerances to ensure parts fall closer to design intent and cutting sheets of metal.
Critical Dimensions
The following are some terminology that are used in sheet metal. Designers need to adhere to machinery guidelines when designing for bending. Bends can be defined by these parameters. Some critical dimensions that need to be considered when setting up sheet metal design in CAD software are sheet metal thickness, the k-factor and bend radius. One needs to check that these factors are consistent with the tooling that will be used in manufacturing.
Bend line– The straight line on the surface of the sheet, on either side of the bend, that defines the end of the level flange/web and the start of the bend.
Bend radius – The distance from the bend axis to the inside surface of the material, between the bend lines.
Bend angle – The angle of the bend, measured between the bent flange and its original position, or as the included angle between perpendicular lines drawn from the bend lines.Sometimes specified as the inside bend radius. The outside bend radius is equal to the inside bend radius plus the sheet thickness.
Neutral axis – The location in the sheet that is neither stretched nor compressed, and therefore remains at a constant length.
K-factor – The location of the neutral axis in the material, calculated as the ratio of the distance of the neutral axis T, to the material thickness t. The K-factor is dependent upon several factors (material, bending operation, bend angle, etc.) and is greater than 0.25, but cannot exceed 0.50. K factor = T/t
Bend allowance – The length of the neutral axis between the bend lines or the arc length of the bend. The bend allowance added to the flange lengths is equal to the total flat length.
Software Used
NX, formerly known as "unigraphics", is an advanced high-end CAD/CAM/CAE, which has been owned since 2007 by Siemens PLM Software. In this software the sheet metal application is used to design the flat pattern required.
DESIGN METHODOLOGY:
Workflow to design a sheet metal part
Steps For Designing The Odd Shaped Enclosure
DESIGN FEATURES:
The following features are used in the project. This project was designed in the sheet metal module of the Siemens NX CAD.
1. SKETCH-This command is used the draw the shape of the design section.
2. EXTRUDE- This command is used to create a feature by extruding a section along a vector. The shape of the section is created in sketch.
3. FLANGE-This command is used to create the bend part attached to the side of the base feature. A flange of 20mm length is created.
4. JOG- This command is used to create an offset or a step in a tab. NX creates the jog by lifting the material on one side of the jog line and adding a flange between the two sides.
5. UNBEND- This command was used to unbend the bent areas in the sheet metal to get the flattened sheet metal.
6. HOLE- This command is used to create holes at desired location using points.This command is used to create six simple holes of diameter 10mm.
7. BEAD- A bead is a long, drawn-out impression, which is impressed to increase stiffness in metal sheets or plates.This command is used to create two beads.
8. REBEND- This command is used to rebend the unbent areas to obtain the bend features and also to obtain the final sheet metal part.
9. CONVERT TO SHEET METAL- This command is used to convert non-sheet metal parts into sheet metal parts.
10. FLAT PATTERN- This command to to create the flat pattern view which is needed for drafting and later manufacturing purpose for a sheet metal.
FINAL DESIGN MODEL:
FRONT VIEW
SIDE VIEW
Fig: Left side view Fig: Right side view
ISOMETRIC VIEW
TOP VIEW
DETAILED DRAWING
CONCLUSION:
Thus the objective of designing an Odd Shaped Enclosure in the NX CAD Sheet metal application is done successfully. The proper utilization of the commands to get the desired output and also the flat pattern is achieved. The final detailed drawing draft is also derived from the flat pattern.