CASA Part 66: Press Brake Dies

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Questions and Answers

What assists the power of the Flywheel?

Electrical motor

Manual operation

Pneumatic system

Hydraulic power (correct)

What is the main advantage of Throatless Shears?

They are less expensive than other shears

They are heavier and more durable

They are easier to handle

They can cut metal of any length and shape (correct)

What is the primary function of Scroll Shears?

To cut straight lines on a sheet

To bend metal into different shapes

To make irregular cuts on the inside of a sheet (correct)

To cut through the edge of a sheet

What must be considered when manufacturing a sheet metal item?

The overall dimension and bend allowance Signup and view all the answers

What is the cutting action of Throatless Shears similar to?

A pair of scissors Signup and view all the answers

What is the principle of operation of Scroll Shears?

Similar to a can opener Signup and view all the answers

What is the range of standard capacities for mild steel sheet in a cornice brake?

12 to 22 gauge Signup and view all the answers

What is the purpose of the clamping nose bar in a cornice brake?

To hold the job in place and facilitate different thicknesses of material Signup and view all the answers

What happens when the bending leaf is raised higher in a cornice brake?

The bending angle increases Signup and view all the answers

Why is it necessary to bend metal past the desired angle in a cornice brake?

To allow for spring-back Signup and view all the answers

What is the purpose of a radius bar in a cornice brake?

To allow for greater bending angles Signup and view all the answers

What is the primary use of a bar folder?

To bend edges of light material Signup and view all the answers

What is the purpose of cutting or notching waste material in step 4?

To create a snug fit between sides Signup and view all the answers

How are the lengths of sides C and E determined?

By measuring the outside of the box Signup and view all the answers

What is the rule of thumb for the size of relief holes?

Diameter = 2BR Signup and view all the answers

Where should the centre of a relief hole be located?

At the intersection of the inner BTLs Signup and view all the answers

What determines the BTL from which the sight line is measured?

The side that is placed under the folder Signup and view all the answers

What is the purpose of determining the bending sequence in step 6?

To determine which BTLs the sight lines will be measured from Signup and view all the answers

What is the primary use of shears in an aircraft workshop?

Notching out corner material to facilitate folding Signup and view all the answers

What is another name for a treadle guillotine?

Squaring shear Signup and view all the answers

What is the purpose of the clamp in squaring shears?

To hold the job tight Signup and view all the answers

What should be kept clear of the clamp and blade in squaring shears?

Fingers Signup and view all the answers

What type of guillotine is used to cut wider and thicker flat sheet metal stock?

Power guillotine Signup and view all the answers

What type of snips are colour-coded?

Aviation snips Signup and view all the answers

What is the purpose of the K-value in the setback formula?

To apply an additional multiplier to the setback formula Signup and view all the answers

What is the K-value for a 90° bend?

1 Signup and view all the answers

How can you find the K-value if a K chart is not available?

By using the tangent of half of the bend angle Signup and view all the answers

What is the formula for calculating the setback?

SB = K(BR + MT) Signup and view all the answers

What is the purpose of the setback calculation?

To calculate the distance from the neutral axis Signup and view all the answers

What is the value of K for a 60° bend?

0.5773 Signup and view all the answers

Study Notes

Cornice Brake

A cornice brake is used to bend large sheets of metal and can accommodate metal thicknesses from 12 to 22 gauge (0.110 in to 0.032 in) and 3 to 12 ft wide.
It has a sharp nose bar, a bed with a clamping nose bar, and a bending leaf that forms the material around the nose bar/radius block.
The clamping nose bar is adjustable to facilitate different material thicknesses and is actioned by a handle to clamp.
The bending leaf is adjustable to facilitate different radii and is counterweighted to aid the operator in bending.

Bar Folder

A bar folder is used to bend edges of light material.

Calculating Lengths of Flats

To calculate the lengths of flats, consider which two sides will fit inside the other two.
Cut or notch waste material, and decide which sides will fit inside the other two.
The length of C and E should be the same as the outside of the box, while D and F should be the length of the box minus 2MTs.

Maintenance Practices

Use relief holes to prevent cracks emanating from the corners of bends.
The centre of a hole must be at the intersection of the inner BTLs.
Determine the bending sequence and mark sight lines.
Think about the bending sequence and how it will affect which BTLs your sight lines will be measured from.

Sheet Metal Cutting Tools

Hand shears include aviation snips and tin snips, used for notching out corner material to facilitate folding.
A treadle guillotine is used to cut flat sheet metal stock and has a foot-operated blade.
Squaring shears have side fences as guides to enable a square cut and incorporate a clamp to hold the job tight.
A power guillotine is a foot-operated, power-assisted tool used to cut wider and thicker flat sheet metal stock.
Throatless shears are a hand-operated tool that allows more mobility in cutting and can cut metal of any length and any shape.
Scroll shears are used to make irregular cuts on the inside of a sheet without cutting through the edge.

Sheet Metal Working

To manufacture a sheet metal item accurately, consider the physical changes that occur inside the metal when bending.
Calculate the bend allowance and add it to the overall dimension to finish with the correct size component after bending.
The neutral axis is the point where the metal does not change length during bending.

Setback

For bends greater or less than 90°, the setback (SB) will be different, and an additional multiplier (K-value) is applied to the SB formulae.
The SB formulae becomes: SB = K (BR + MT).
For a 90° bend, the K-value is 1.
Use K charts or the formula K = Tangent of half of the Bend Angle to determine the K value for given angles.
Example: For a 60° bend, the K-value is K60° = tan 30° = 0.5773.

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Description

This quiz covers the basics of press brake dies, including cornice brakes and their capabilities in bending metal sheets of varying thicknesses.