lecture solidworks sheetmetal

7/28/2019 Lecture Solidworks Sheetmetal

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Sheet-Metal

A large proportion ofproducts around us aremade out of sheet-metal

Electronic enclosures,white-ware, cars,hardware, computercomponents, robots, etc.

Most common metalsused are aluminium andsteel


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Sheet-Metal Manufacturing

Methods CNC Fabrication Laser cutting

Bending Hard-tooled

Spun


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Bending

Bending is a manufacturing process by whichmetal can be deformed by plastically deforming

the material and changing its shape. The material

is stressed beyond its yield strength but below its

ultimate tensile strength.


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Bending

Bending is done using Press Brakes or bendbrakes. Press Brakes can normally have acapacity of 20 to 200 tons to accommodatestock from 1m to 4.5m

The material is placed on the die, andpositioned in place with stops and/or gages. Itis held in place with hold-downs. The upperpart of the press, the ram with theappropriately shaped punch descends and

forms the v-shaped bend.

Programmable back gages, and multiple diesets currently available can make bending avery economical process


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Types of Bending

Bending

Blank

Punch

DieDie

Punch

Blank


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Types of Bending

Bottoming

Blank

Die

Punch

Blank

Punch

Die


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Types of Bending

Coining

Die

Blank

Punch

Blank

Punch

Die


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Bend Allowances

When sheet metal is bent, the inside surface ofthe bend is compressed and the outer surface ofthe bend is stretched. Somewhere within thethickness of the metal lies its Neutral Axis, which

is a line in the metal that is neither compressednor stretched

The location of the neutral line varies dependingon the material itself, the radius of the bend, theambient temperature, direction of material grain,and the method by which it is being bent, etc.The location of this line is often referred to as theK factor


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Bend Allowances

K-factor is a ratio that represents thelocation of the neutral line with respect

to the thickness of the sheet metal part.

T

t

K-Factor = t /T


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Bend Allowances

If you have a 100mm long flat bar of2mm Aluminium and bend it at 90 deg

in the middle, the 2 legs will NOT

measure 50mm each. In fact they will

measure around 51.8mm each

Length X

Length

YTotal Flat Length

STEP 1 STEP 2

Thickness


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Bend Allowances vs Bend Deductions

Lt= L1 + L2 + BA L

t= L1 + L2 - BD

where:

Lt = total flat length

L1 and L2 are shown in the

illustration

BA = bend allowance value

where:

Lt = total flat length

L1 and L2 are shown in the

illustration

BD = bend deduction value

L2

L1 BEND

ALLOWANCE

L2

L1 BEND

DEDUCTION


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Calculating Bend Allowances

BA= A(R + KT) /180where:

BA = bend allowance

R = inside bend radiusK = K factor, which is t / T

(usually 0.25-0.5)

T = material thickness

t = distance from inside face

to neutral line

A = bend angle in degrees


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Calculating Bend Deductions

BD = 2 x OOSB - BA

OSSB = tan(A/2) x T + R


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Sheetmetal Rules

Rules in SolidWorks for Sheetmetal:

Parts have a constant thickness

Thickness faces are always perpendicular to thebend faces (material is never sheared at an angle)

The bend faces are limited to cylindrical, planar,conical shapes

The exceptions are form tools and Lofted Bends


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The Flatten Test

Can it be flattened?

Why?? Or Why not??

Ans. = Yes, All cones


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The Flatten Test

Can it be flattened:

Why?? Or Why not??

Ans. = No, Spline


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Sheetmetal Functions

InsertBen

ds

FlattenBen

ds

NoBen

ds

R

ip

B

aseFlange/T

ab

MiterFlan

ge

Fo

ld

Unfo

ld

SketchedBen

ds

EdgeFlan

ge

ClosedCorn

er

He

m

Bre

ak/TrimCorn

er

J

og

LoftedBe

nd

New SchoolOld School


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Two Basic Methods

There are two basic methods SolidWorks

sheetmetal can be used:

Model the part using regular SolidWorks

functions like extrude, revolve, etc.

Generally used only for imported parts and

rolled parts

Start with an open sketch and a Base

Flange feature

Much more powerful

Way more options


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Base Flange

Base Flange requires an open sketch


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Edge Flange

Select an edge, hit the

button, pull the flange

Flange Length and

Position buttons are self

explanatory

Offset allows

you to create a

dogleg flangeYou can also

change the angle

of the flange


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Edge Flange

Edit Flange Profile allows you to change the

sketch of the flange and alter the shape


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Miter Flange

Miter Flange requires an open sketch on the

edge of the part

Sketch

Propagate to

tangent

Allowance for

flattening


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Fold / Unfold

To put a feature across a bend, unfold the bend,

put in the feature, then fold it again

Use offset entities tomake slots!

Select face to

remain stationary

Collect finds all theunfolded bends


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Tab

There are no settings for the Tab function,

it just adds a tab to the sketch face

Sk t h d B d


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Sketched BendDraw a line all the way across the part

Dont cross bend lines

Line must go all the way across

Control bend angle and direction

Black dot selects stationary face


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JogLike a double sketched bend

Allows you to keep the original length of the tab oradd material as it jogs


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HemsButtons and dimensions are self explanatory


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Corner Break

Chamfers or rounds sharp outside corners

Puts you into a selection filter model to pick short

edges across the thickness and bend faces

Selecting a face breaks all corners on face


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Forming ToolsForming tools drag and drop from the Design Library

Forming tools maintain a constant thickness (theymay add mass to the part)

Red faces create holes in the part

Only works on sheetmetal parts


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Old SchoolChamfers or rounds sharp outside corners

Build box shellRip

corners

Insert

bends

Flatten


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Finer Points

How does SW handle bend allowances?

K Factor

Bend Allowance

Bend DeductionBend Table

A very good mathematical description of

how SW handles bend allowances isavailable as a Knowledge Base article on

the SW website.


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Finer PointsHow does SW handle bend reliefs?

Tear = zero thickness cut

Rectangular = default depth is half of thickness

Obround = full round cut

These settings are kept in the Sheetmetal feature in

the tree.


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Finer Points

Sheetmetal automatically creates a link value

called thickness, which allows the thicknessof the entire part to be changed at once

Link Value symbol

lecture solidworks sheetmetal

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