Proper Method to Produce Lobster-back Duct Bends

Proper Method to Produce Lobster-back Duct Bends

Learning Objectives

At the end of the lesson you will understand the process of designing and manufacturing lobster-back bends. At the end of the lesson you will know how to correctly produce a DXF file for CNC cutting of duct bend segments. At the end of the lesson you will be able to modify a DXF file to optimize it for the manufacturing process.

What do you already know about lobster-back duct bends?

Overview of Lobster-back Bend Design and Manufacturing

Industrial duct components made from segments cut and rolled from flat sheets or plates.

Importance of Accurate 1:1 Scale in DXF Files for CNC Cutting

Efficient nesting of parts on a sheet is crucial for manufacturing efficiency.

Steps to Efficiently Nest Parts on a Sheet for Manufacturing

Modifications to the DXF file include removing overlapping lines and replacing short line segments with 3-point arcs.

Modifications Required in DXF Files to Improve CNC Machine Performance

Creating breaks in the profiles to keep parts connected for easier rolling. Considerations for kerf in laser, plasma, and water-jet cutting machines.

Considerations for Kerf in Cutting Machines

The kerf from cutting is typically small enough to ignore, but adjustments can be made if necessary.

Summary of Learning Goals

Understand the process of designing and manufacturing lobster-back bends. Know how to correctly produce a DXF file for CNC cutting of duct bend segments. Be able to modify a DXF file to optimize it for the manufacturing process.

Definition List

Lobster-back bend: A duct bend composed of segments that are cut from flat material, rolled into shape, and assembled to form the bend. DXF file: A file format for CAD data exchange, used to transfer drawings to CNC machines for cutting. Kerf: The width of the cut made by a cutting torch or tool, which may need to be considered in the cutting process. Nesting: The process of laying out patterns of parts to be cut from materials in a manner that minimizes waste. 3-point arc: A method of drawing arcs in CAD software using three points to define its circumference, often replacing many short line segments.

Write down 3 things you learned in this lesson.

Have students enter three things they learned in this lesson. With this they can indicate their own learning efficiency of this lesson.

Write down 2 things you want to know more about.

Here, students enter two things they would like to know more about. This not only increases involvement, but also gives them more ownership.

Ask 1 question about something you haven't quite understood yet.

The students indicate here (in question form) with which part of the material they still have difficulty. For the teacher, this not only provides insight into the extent to which the students understand/master the material, but also a good starting point for the next lesson.