Manual de Teoria Amada Press Brake

Glossary

ACUTE ANGLE: An included angle tighter (less than) than 90 degrees. (The

material has been bent past 90 degrees) (see page 5)

AIR BEND: A bend determined by one line of force against two lines of

resistance. The BEND RADIUS is determined by die width and

material thickness. The bend angle is determined by punch

penetration.

APEX: The imaginary point where the two sides of an angle, if extended,

would meet. (see page 5)

BED: The load bearing surface of the lower beam.

BEND ALLOWANCE: The length of the neutral line through the bend from tangent line

to tangent line.

BEND DEDUCTION: Amount deducted from overall size to determine shear

dimensions. Abbreviated as B/D. Also known as “K” factor.

Equal to two times “set back”.

BEND LINE: Line on work piece where punch contacts material.

BEND RADIUS Curvature of material at the bend, expressed as distance from the

material to the center point of that bend. Also see Inside Radius.

BOTTOM BENDING: When material is pressed between the punch and die, the punch

tip penetrates the material. The inside radius is determined by the

punch tip. Bend angle is determined by tooling.

COINING: Process of bending by applying large amounts of force to cause

material to flow. Springback is eliminated, because the material

in the bend zone undergoes plastic deformation. The inside radius

of the bend is determined by the radius of the punch tip.

DIE: The concave, or female tool. Normally mounted on the bed, or on

spacers mounted on the bed.

DISTANCE PIECE: Punch holders on Amada style machine. Used to adjust for

varying amounts of ram and/or beam deflection.

FLANGE: The portion of sheetmetal that has been formed up or down to

obtain rigidity or desired shape.

Amada School Bending Workbook Version 1.4d, April 2002

Page 2 Glossary

HEM: A bend where the sheetmetal is folded over on top of itself. This

may be done to provide a smooth edge, to provide stiffness, or to

join two pieces together.

INCLUDED ANGLE Angle formed around the punch.

INSIDE RADIUS Distance from the inside surface of the material at a bend to the

center point of that bend. Abbreviated as IR. (see page 5)

HYDRAULIC Machine driven by fluid power provided by hydraulic pump.

NEUTRAL LINE: Line through the material that remains at constant length when

the material is bent. (see page 26) Used for flat pattern

development.

OBTUSE ANGLE: An included angle of greater than 90 degrees. (The sheet metal

has not been bent far enough to reach 90 degrees)

OPEN HEIGHT: Distance between the ram and bed of machine when the ram is

fully retracted.

PRESS BRAKE: Machine designed to form metal parts using punch and die.

PUNCH: The convex (male) tool. Normally mounted to the upper beam.

RAM: Beam that moves to supply bending force, can be upper or lower.

SET BACK: Amount of material deducted from flange length to place bend

line. Same as ½ of the bend deduction or ½ “K” factor.

SHEAR SIZE Dimension of blank piece before bending.

SHUT HEIGHT: Distance between upper and lower beams when the ram is fully

extended.

SPRINGBACK: Tendency of material to return to flat condition after forming.

(see page 26)

TANGENT: The point where a line meets a radius.

TENSILE STRENGTH: Measurement of resistance (in pounds/square inch or similar

units) that metal can be stretched before fracture.

UPPER BEAM: Upper part of machine that holds tooling and supplies bending

force or resistance depending on machine style.

YIELD STRENGTH: Measurement of resistance (in pounds/square inch or similar

units) that metal can be stressed before forming.

Version 1.4d, April 2002 Bending Workbook Amada School

Glossary Page 3

The Basics of Brake BendingIn brake bending, the material is supported by a die and a punch is forced intothe material. The punch is centered between the two edges of the die, causingthe material to bend evenly on each side of the punch.

The first illustration below showsa punch and die with materialpartially bent. The secondillustration shows some of theforces involved and the materialmotion during the bend.


Page 4 The Basics of Brake Bending

Simple bend

Punch

materialmotion

materialmotion

Die

Forces in simple bend

Bend Angle

When sheet metal is bent in a press brake, it (usually) begins “in the flat”. Asit is bent, the angle can be described by either of two numerical values:

The “included angle” is the angle formed around the punch.

The “complementary angle” is the amount the metal has been bent from flat.

The two angles always sum to 180 degrees.


The Basics of Brake Bending Page 5

f H

30°

IR

IR

IR

Angle A

Angle A

Apex

90°90°

1.815"

135°

45°0.234"

45 complementary angle,

135 included angle

°

°

T

Materials

Materials

Purpose of chapter

This chapter contains general information about various materials, such asCarbon Steel, Aluminum and various alloys. Also presented are Inch-Metricconversions, Fraction to decimal equivalents, and sheet weights for variousmaterial thicknesses and sheet sizes.


Page 10 Materials

Conversions


Materials Page 11

InchFractions

InchDecimal

Milli-meters

1/64 0.015625 0.397

1/32 0.031250 0.794

3/64 0.046875 1.191

1/16 0.062500 1.588

5/64 0.078125 1.984

3/32 0.093750 2.381

7/64 0.109375 2.778

1/8 0.125000 3.175

9/64 0.140625 3.572

5/32 0.156250 3.969

11/64 0.171875 4.366

3/16 0.187500 4.763

13/64 0.203125 5.159

7/32 0.218750 5.556

15/64 0.234375 5.953

1/4 0.250000 6.350

17/64 0.265625 6.747

9/32 0.281250 7.144

19/64 0.296875 7.541

5/16 0.312500 7.938

21/64 0.328125 8.334

11/32 0.343750 8.731

23/64 0.359375 9.128

3/8 0.375000 9.525

25/64 0.390625 9.922

13/32 0.406250 10.319

27/64 0.421875 10.716

7/16 0.437500 11.113

29/64 0.453125 11.509

15/32 0.468750 11.906

31/64 0.484375 12.303

½ 0.5000000 12.700

33/64 0.515625 13.097

17/32 0.531250 13.494

35/64 0.546875 13.891

9/16 0.562500 14.288

InchFractions

InchDecimal

Milli-meters

37/64 0.578125 14.684

19/32 0.593750 15.081

39/64 0.609375 15.478

5/8 0.625000 15.875

41/64 0.640625 16.272

21/32 0.656250 16.669

43/64 0.671875 17.066

11/16 0.687500 17.463

45/64 0.703125 17.859

23/32 0.718750 18.256

47/64 0.734375 18.653

3/4 0.750000 19.050

49/64 0.765625 19.447

25/32 0.781250 19.844

51/64 0.796875 20.241

13/16 0.812500 20.638

53/64 0.828125 21.034

27/32 0.843750 21.431

55/64 0.859375 21.828

7/8 0.875000 22.225

57/64 0.890625 22.622

29/32 0.906250 23.019

59/64 0.921875 23.416

15/16 0.937500 23.813

61/64 0.953125 24.209

31/32 0.968750 24.606

63/64 0.984375 25.003

1 1.000000 25.400

1” = 25.4 mm = 2.54 cm

1 cm = 0.3937”

1 mm = 0.0394”

MM to Inch


Page 12 Materials

MM INCH

0.1 0.0039

0.2 0.0079

0.3 0.0118

0.4 0.0157

0.5 0.0197

0.6 0.0236

0.7 0.0276

0.8 0.0315

0.9 0.0354

1 0.0394

2 0.0787

3 0.1181

4 0.1575

5 0.1969

6 0.2362

7 0.2756

8 0.3150

9 0.3543

10 0.3937

11 0.4331

12 0.4724

13 0.5118

14 0.5512

15 0.5906

16 0.6299

17 0.6693

18 0.7087

19 0.7480

20 0.7874

21 0.8268

22 0.8661

23 0.9055

24 0.9449

25 0.9843

26 1.0236

27 1.0630

28 1.1024

29 1.1417

MM INCH

30 1.1811

31 1.2205

32 1.2598

33 1.2992

34 1.3386

35 1.3780

36 1.4173

37 1.4567

38 1.4961

39 1.5354

40 1.5748

41 1.6142

42 1.6535

43 1.6929

44 1.7323

45 1.7717

46 1.8110

47 1.8504

48 1.8898

49 1.9291

50 1.9685

51 2.0079

52 2.0472

53 2.0866

54 2.1260

55 2.1654

56 2.2047

57 2.2441

58 2.2835

59 2.3228

60 2.3622

61 2.4016

62 2.4409

63 2.4803

64 2.5197

65 2.5591

66 2.5984

67 2.6378

MM INCH

68 2.6772

69 2.7165

70 2.7559

71 2.7953

72 2.8346

73 2.8740

74 2.9134

75 2.9528

76 2.9921

77 3.0315

78 3.0709

79 3.1102

80 3.1496

81 3.1890

82 3.2283

83 3.2677

84 3.3071

85 3.3465

86 3.3858

87 3.4252

88 3.4646

89 3.5039

90 3.5433

91 3.5827

92 3.6220

93 3.6614

94 3.7008

95 3.7402

96 3.7795

97 3.8189

98 3.8583

99 3.8976

100 3.9370

0.001” = 0.0254 mm

Standard gauges of sheet metal


Materials Page 15

Specifications of selected Materials


Page 16 Materials

Other Alloys


Materials Page 17

Type Element StockYield

StrengthTensile Strength Rockwell

Hastelloy-X Co 1.5 Fe 18.5 Cr 22.0Mo 9.0 W0.6 C0.15

C0.17 Ni bal.

Wrought Sheetmill annealed

Investment Cast

26000-

23300

5600033500

-

20.818.4

-

Application: high strength, high temp engine parts, resistant to oxidation at high temps.

Hastelloy-C Cr 16.0 Fe 6. W 4. C.15 Mo 17. Ni bal.

Sand cast (anneal.)Investment castRolled (anneal.)

250002500035500

390004000065000

21.32322


Inconel-C Cr 13. Cb 2.Mo 4.5 C .15

Ti .6 Al 6.Ni (+Co) bal.

Investment cast(anneal.)

5100060000

Application: high strength, high temp engine parts, resistant to oxidation at high temps

Inconel-X Ni (+Co) 72.85Mn .65 S .007Cu .05 Al .75

Cb (+Ta) .85 .04 Fe6.8 Si .3

Cr 15. Ti 2.5

(Anneal.)Age Hardened

2500052500

5250087500

1632.2


Waspoloy C .08 Cr 19.5 Mo 4.3Ti 3. Co 13.5

Cold Rolled 13500 137500 51


Udimet 700 C .08 Cr 15. Mo 5. Ti3. Al 4.3 Co 18.5

Cold Rolled 140000 142500 53


Zinc-40 Cu 1. Zn bal. Hot RolledCold Rolled

--

1200015500

5.66.4

Application: Weatherstripping, spun pieces.

Zinc ASTMB69

Cd .35 Pb .08 Zn bal. Hot Rolled 9.75 4.1

Zilloy-15 Cu 1.0 Mg .01Zn bal.

Hot RolledCold Rolled

14.5 6.5


Page 18 Materials

Aluminum


Materials Page 19


Page 20 Materials

Notes on Aluminum

Three common grades of aluminum are:

5052-H32 Easy to work with, warps easily.

5051-H32

6061-T6 Usually quite flat but doesn’t form well. (cracks)

Hardness may be designated by “T” and a number, 0~80 = dead soft2 = ¼ hard4 = ½ hard6 = ¾ hard8 = full hard


Materials Page 21

Bending Theory

Bending TheoryThis chapter describes how material responds to bending stress, the three typesof bends, and what happens to the work piece as it is being formed.

Stresses and springback

While a blank is still flat, both sides and the middle are all the same length. Aswe form the material in the die space the material towards the inside of theneutral line is compressed, and the material towards the outside of the neutralline is stretched. Material that is compressed or stretched enough will staypermanently deformed. That material has been “plastically deformed”.

Now picture a band of metal following the neutral line that has not beencompressed or stretched enough to reach a “plastic” condition. This band ofmaterial maintains an “elastic” condition. This elastic material will tend toreturn to its original unbent position, tending to straighten the material. Theforces of the “elastic” metal (trying to return to its original condition) and theforces of the “plastic” metal (trying to stay permanently deformed) come to anequilibrium, determining “spring back”.

☞ The amount of spring back is determined by the amount of materialstressed enough to reach a plastic condition.

Harder metals will have more spring back due to the higher elastic limit, whichresults in a larger elastic band at the bend.

As metal is bent farther (through more degrees) the plastic zone becomeslarger, reducing the amount of springback.

A sharper or smaller bend radius will reduce spring back by creating a largerplastic zone, due to the higher tensile stresses at the outside surface of thematerial at the bend radius. This may also cause tearing or fracturing.


Page 26 Bending Theory

NEUTRAL AXIS

TENSILE STRESSES

COMPRESSIVESTRESSES

OUTER ZONE PLASTICALLYDEFORMED BY TENSION

INNER ZONE PLASTICALLYDEFORMED BY COMPRESSION

ELASTIC ZONE

SPRINGBACKNEUTRAL AXIS

SPRINGBACKFORCES

Considering no change in the inside radius, thicker materials have less springback since there is more plastic deformation.

Overcoming Spring backMethods of overcoming spring back include over-bending, bottoming orsetting, and stretch bending.

OVER BENDING is bending the material past the target angle, so that it re-laxes to the correct position. This may be accomplished using common meth-ods: tooling with an angle smaller than the required bend, or cam dies.BOTTOMING consists of striking the metal severely at the radius. This com-presses the material beyond the yield strength and causes a larger plastic zone.Bottoming must be carefully controlled. When adjusting ram depth settings,forces will rise at a high rate, careless operation can cause die breakage andeven machine failure.STRETCH BENDING uses a special setup or special tooling to stretch theworkpiece to bring the entire bend zone into yield, so that it retains its shapewhen released.

When a work piece is flat the neutral line is in the center of the material. Asthe material is formed the neutral line shifts toward the inside radius of thebend.

As the radius of the bend is decreased the neutral axis of the material will shiftcloser to the inside surface.

The length of the neutral axis, which is the object of the blank sizecalculations, is dependent on the following factors:

type of forming employedmaterial type and hardnessinside bend radius (as related to material thickness)grain direction

Since the neutral line is affected by each of the variables listed, accurateblank size calculations can be difficult. There are several methods or formulascommonly used to calculate precise blank sizes. These formulas and charts arelisted in the Bend Allowance Chapter. (See page 46 )


Bending Theory Page 27

Bending Methods

There are basically three types or methods of bending sheetmetal with a pressbrake: Air Bending, Bottoming, and Coining

Air BendingThe angle is determined by the penetration of the punch tip into the dieopening. The inside radius of the bend is determined by the width of the dieopening, except soft materials such as some aluminums which may conform tothe punch radius. An inside radius of 15% of the vee die width can be expectedwhen forming mild steels. Smaller vee die widths decrease inside radius whileincreasing tonnage requirements.

If the die width is too small, excessive tensile stresses will occur, which cancause fracturing. Larger die widths increase inside radius and reduce tonnage.Excessive die width will draw too much material into the vee and may cause abulge in the outside radius of the bend.

Air bending requires minimum tonnage,extending the brake’s capacity and reducingwear. Tooling becomes more versatile and less“per job” tooling is required.

Air forming is practical for precision work. Theability to determine the inside radius by veewidth rather than punch radius can increase theshop versatility, allowing the brake operator to“fudge” on bend deduction figures by changinginside radiuses. This allows the operator the ability to adjust for blanks thatmay not meet tolerances. Within reasonable vee sizes, material imperfectionswill not greatly affect the given angle.


Page 28 Bending Theory

Bottom Bending

Bottoming is accomplished by striking thematerial severely at the bend radius. Toolingconfiguration determines bend angle, partshape, and inside radius. Material greater than16 gauge is seldom bottomed due to the largetonnage requirements.

Bottoming puts a tremendous amount of forceon the brake and tooling. Great care must betaken during set up to avoid damage tomachine tooling and the operator. Pressmaintenance becomes crucial to press life. Bending accuracy can be veryconsistent but extensive set up by experienced operators must take place first

CoiningA coining operation is one in which the amount of force applied to the workpiece is enough to cause the material to “flow”. If you look at the cross sectionof a coin you will notice that the material has been struck so hard that thematerial between the thinner areas of the die set have been forced to “flow”into the thicker areas. Forces of 100 tons per square inch are not uncommon.Coining is seldom performed on a press brake due to the tonnage requirementsalthough “bottom bending” is often referred to as “coining” in many shops.


Bending Theory Page 29

Blueprint reading

Blueprint readingThis section presents some commonly used symbols, followed by samples andexercises in basic blueprint reading.


Page 34 Blueprint reading

Figure 1

First-angle or Third-angle projection describes how the part is rotated fromview to view.


Blueprint reading Page 35

Perpendicularity

Angularity

Parallelism

Position

.XXX M B C

A ReferencedatumsModifier

Tolerance

Type ofcontrol

Datumsymbol

Third-angle First-angle

U.S. customary projection ISO projection



1.50"

12.00"

1.00"9.00

"

4.50

"

9.00

"2.

00" 2.00"

0.75"

0.206 RO(4 plcs)

Figure 2



0.50"

1.25"

0.63"

0.38"

0.50"

0.688”

1.25"

0.88"

0.375"0.437"

0.875"

Figure 3



0.250"

0.187"

0.500"

1.000”

0.250”

1.000"

0.375"

0.767"

0.126 DIA

(2 PLCS)

0.125"

1.250"

1.250"

Figure 4

The drawing on this page shows an assembly of three individual parts.

On the following pages, the individual parts are drawn.



1.343"

0.563"PART 1

PART 3

PART 2

Figure 5



0.672"

1.657"

0.578"

0.313"

0.501"

0.28

1"

0.40

5"0.

188"

0.25

0"

0.68

8"

1.68

8"

1.844"

Part 1Material thickness: 0.094”

Figure 6



1.657"

0.656"0.313"

2.281"

0.313"

0.078"

0.500"

0.656"

1.125"

0.469"

0.156"

0.156"0.125"

0.125"

1.345"

Part 2

material thickness: 0.094”

Figure 7



0.344" 0.297"

1.657"

0.500"

0.156"

0.156"

1.000"

0.688"

0.313"0.375"

1.033"

0.312"

0.359"

0.280"

1.406”

1.657"

0.125"

Material thickness: 0.094”

Part 3

Figure 8

Bend AllowanceBend Deduction

Bend Allowance, Bend Deduction

Introduction

When bending material, several factors must be considered to create accurateresults. The neutral line, (herein referred to as N/L), is an imaginary line thatsplits the material thickness. The N/L is used in blank developmentcalculations.

The N/L is easily measured when the stock is flat. (See Figure 9) Now let usconsider this same piece of stock after it has been formed to 90 degrees.

Note the location of the N/L in reference to the measure points. On the left endof figure 10 the N/L is unchanged. On the right side the N/L is within thematerial and can’t be measured directly. In the shop we can only measurefrom the outside or the inside of the flange at point B. Measuring to theoutside edge of the flange is usually easy and accurate, and has become themost common and preferred way to develop flat patterns. In either case(outside or inside measurement)we must compensate for thematerial that is between themeasurement point and the N/L.


Page 46 Bend Allowance, Bend Deduction

AA

NEUTRAL LINE

Neutral line touchescalipers at points A

Figure 9: N/L of flat material

BA

NEUTRAL LINE

Neutral line touches calipers atpoint A, but not at point B

Distance between theedge of the part andthe Neutral Line

Figure 10: N/L of material with bend

Bend Deduction

This material that lies between the N/L when measuring between points “A”also exists if we measure between points “A”, “B”. This would seem to makethe part “grow” when bent. The material does stretch some and, as wediscussed in the chapter on “theory”, we know that the N/L shifts a littleduring bending.

The “Bend Deduction” (hereinafter referred to as B/D) found in the charts orformulas in this book is adequate for most jobs. This assumes that precisionequipment is used and the tooling setup is known and correct for the job.

This also assumes that the material thickness and strength correspond to thoseused in developing the charts.

In some cases, it may be necessary to make a test bend using actual toolingand material.

Bend Radius

All the computations for bend allowance and bend deduction assume that thebending radius is known. The bend radius may be predicted as follows:

Bottoming or Coining:Punch tip radius = bend inside radius.

Air Bending:Determined by material thickness and Vee-Die opening. See the “Air BendingForce Chart” in the Amada Press Brake Tooling catalog.

Usage of Bend Deduction

The bend deduction method is most useful when a part (or bend within a part)is at 90 degrees or is dimensioned to the apex of the bend. When a bend is not90 degrees and is dimensioned to the material instead of the apex, the bendallowance method may be easier. (see page for the bend allowance method)

To use B/D: add the outside (apex) dimensions together, then subtract one B/Dfor each of the bends in the part.

Note: for a 90 degree bend, the “outside” dimension is the same as thedimension to the apex of the bend.

On the following pages we have provided a “Bend Deduction” chart for 90degree bends. This chart is generated from formula 3 on page 50.

The chart is provided for classroom use, and not shop use.


Bend Allowance, Bend Deduction Page 47



Insi

deR

adiu

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010

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172

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80.

185

0.19

10.

197

0.20

50.

218

0.22

50.

231

0.23

9

0.12

50.

174

0.17

60.

178

0.18

50.

192

0.19

80.

204

0.21

20.

225

0.23

20.

238

0.24

5

0.13

50.

187

0.19

00.

192

0.19

90.

205

0.21

20.

217

0.22

60.

239

0.24

60.

251

0.25

9

0.18

80.

260

0.26

20.

265

0.27

10.

278

0.28

50.

290

0.29

80.

312

0.31

90.

324

0.33

2

0.25

00.

345

0.34

70.

350

0.35

60.

363

0.37

00.

375

0.38

30.

397

0.40

40.

409

0.41

7



Insi

deR

adiu

s>

0.19

00.

203

0.21

90.

234

0.25

00.

312

0.34

40.

375

0.43

00.

500

Mat

eria

lth

ickn

ess

bend

dedu

ctio

n

0.01

60.

104

0.10

90.

116

0.12

30.

129

0.15

60.

170

0.18

30.

207

0.23

7

0.01

80.

106

0.11

20.

119

0.12

50.

132

0.15

90.

173

0.18

60.

210

0.24

0

0.02

00.

109

0.11

50.

122

0.12

80.

135

0.16

20.

175

0.18

90.

212

0.24

2

0.03

00.

123

0.12

80.

135

0.14

20.

149

0.17

50.

189

0.20

20.

226

0.25

6

0.03

20.

126

0.13

10.

138

0.14

50.

151

0.17

80.

192

0.20

50.

229

0.25

9

0.03

60.

131

0.13

70.

144

0.15

00.

157

0.18

40.

197

0.21

10.

234

0.26

4

0.04

00.

137

0.14

20.

149

0.15

60.

162

0.18

90.

203

0.21

60.

240

0.27

0

0.04

80.

148

0.15

30.

160

0.16

60.

173

0.20

00.

214

0.22

70.

251

0.28

1

0.05

00.

150

0.15

60.

163

0.16

90.

176

0.20

30.

217

0.23

00.

254

0.28

4

0.05

60.

159

0.16

40.

171

0.17

70.

184

0.21

10.

225

0.23

80.

262

0.29

2

0.05

90.

163

0.16

80.

175

0.18

20.

188

0.21

50.

229

0.24

20.

266

0.29

6

0.06

00.

164

0.17

00.

176

0.18

30.

190

0.21

60.

230

0.24

40.

267

0.29

7

0.06

30.

168

0.17

40.

181

0.18

70.

194

0.22

10.

234

0.24

80.

271

0.30

1

0.07

40.

183

0.18

90.

196

0.20

20.

209

0.23

60.

249

0.26

30.

286

0.31

7

0.08

00.

191

0.19

70.

204

0.21

00.

217

0.24

40.

258

0.27

10.

295

0.32

5

0.09

00.

205

0.21

10.

218

0.22

40.

231

0.25

80.

271

0.28

50.

308

0.33

8

0.10

50.

226

0.23

10.

238

0.24

50.

252

0.27

80.

292

0.30

50.

329

0.35

9

0.12

00.

246

0.25

20.

259

0.26

50.

272

0.29

90.

313

0.32

60.

350

0.38

0.12

50.

253

0.25

90.

266

0.27

20.

279

0.30

60.

319

0.33

30.

356

0.38

7

0.13

50.

267

0.27

30.

279

0.28

60.

293

0.31

90.

333

0.34

60.

370

0.40

0

0.18

80.

340

0.34

50.

352

0.35

90.

365

0.39

20.

406

0.41

90.

443

0.47

3

0.25

00.

425

0.43

00.

437

0.44

40.

451

0.47

70.

491

0.50

40.

528

0.55

8

Bend Allowance

There are several ways that formedparts are dimensioned. In certaincases it is easier to add the flatsegments of a piece (measured totangent points rather than apex)together, then add a “bend allowance”.

Bend Allowance is the length of theN/L between tangent lines.(see figure 11)

☞ Note:The “bend angle” used in Formulas 1, 4 (below) is the

complementary angle, not the included angle.(For angle definitions, conversions, and illustrations, see thefollowing pages)

B/A, B/D Formulas

Formula 1 is used to compute the B/A. This may be needed when computingblank layout or finding the B/D for an angle much bigger or smaller than 90degrees.

Formula 1:[(.0078 x Mat. Thickness )+ (.017453 x IR)] x bend angle = B/A

Bend Deduction Formulas

Formulas 2, 3 provide the B/D for a 90 degree bend. When used for non-90degree bends, they will be less accurate. For high accuracy of non-90 bends,see formula 4 on page 51.

Formula 2:

(3 x (Mat. Thickness + IR)) x = B/D for 90°

Formula 3:(.43 x IR) + (1.372 x Mat. Thickness) = B/D for 90°



Tangent line

BA = Length ofNeutral Axis

Tangent line

I.R.

T = 0.048”

R = 0.030

Figure 11

0.454 for air bend

0.434 for bottom bend

Bend Deduction (cont.)

To determine B/D for angles other than 90 degrees, use formulas 1 and 4.Formula 1 provides the B/A , which is used in formula 4 to develop the B/D.

Formula 4:

( )22

×

× +

−

Tan

Bend AngleMtrlThickness IR B A/ *

=B D/

* See formula 1 (page 50) for B/A*Note: Any B/D divided in half equals “set back” for that bend.

Arc LengthArc Length: The length of a segment of a circle. This formula is used in stepbending.

6 28180

360.

*× ×

−

=radius

AArc length

*A = Included angle as shown infigures - on page 52.

AnglesThe “Included Angle” is the anglemeasured on the inside of thematerial. It is the angle used whenprogramming an Amadabackgauge.

The examples on the followingpage illustrate “included” and“complementary” angles, as well asother details of a bend. Also seepage 5.



Tangent line

Outside arc length Tang

ent l

ine

T = 0.048”

R = 0.030

Figure 12

Angles (continued)The complementary angle andincluded angle always add up to180° .Acomp. Aincluded+ =180deg



IR

135°

45°

45 complementary angle

135 included angle

°

°

Figure 13: Obtuse angle

IR

Angle A90°90°

90 complementary angle,

90 included angle

°

°

Figure 14: Right angle

IR

Angle A

Apex

150 complementary

angle, 30 included angle

°

°

T

30

150°

Figure 15: Acute angle

When to Use B/A

Figure16 depicts a piece bent at an acute angle.

Length B can be directly measured, as can the thickness. When a drawing isdimensioned to B or C as shown, use the B/A method (formula 1, page 50)

If the bend is dimensioned to the apex, use the B/D method instead.(beginning page 47)



IR

Apex

B

B

IR+thkthk

C

Figure 16: Measuring acute angle

Hems

HEM: Where the material is folded on top of itself.

It is generally safe to use 43% of the material thickness for a hem deduction(up to about 0.080 thick).

For tolerances closer than about ± .005 in both directions, it is better topretest a piece of the material

Open Material Hem: Hem deduction is usually 0.Material is folded over with a gap of 1 material thickness left between thehem.

Note: Depending on how hard a hem is hit with a set of flattening dies the hemdeduction can vary.



x 0.430.025 (hem deduction)

0.059 (material thickness)

± .005

± .005

Figure 17: Closed Hem

.750 .750-.025 (hem deduction)

2.25

.725+2.250

2.975 = developed length

Material thk.

Material thk.Distortion from flattening

Coining squeezes material out

Joggles

Generally, a joggle is formed by making a single hit with a special punch anddie set. A test bend can be made with the material to be used, if the adjustmentis not already known for the particular tool and material combination.



IF THIS DIMENSION IS EQUAL TO A MATERIALTHICKNESS THEN IT IS CALLED AN OFFSET

MATERIAL IS PULLED INWHEN FORMING A JOGGLE

“JOGGLE ADJUSTMENT”

PART MEASUREMENT + JOGGLE ADJUSTMENT = BLANK LENGTH

2.952"

Figure 18

Flat Pattern Development

Flat Pattern DevelopmentFlat pattern development consists of several steps. These include calculation ofshear size, location of holes in the flat, determining other features such asnotches, and drawing or sketching the actual flat pattern.

Dimension Points

For bends other than 90° , the dimensions may be to the apex, or the tangentlines, or the physical inside or outside of the bend. For a 90° bend, the apexand outside measurements are the same.

Determining Shear Size

This procedure uses the B/D method.Step 1: Closely check the way your blueprint is dimensioned. Note which

dimensions are to the outside and or inside of the material.

Step 2: Determine Material thickness.

Step 3: Add together all of the OUTSIDE dimensions. (At each dimension calledout to the inside, add one material thickness to get the outside dimension.)

Step 4: Determine IR. (Refer to tooling catalog if needed)

Step 5: Use the B/D charts (pages 48, 49) or one of the formulas (page 50) todetermine the B/D. If more than one bend angle is used, then compute theB/D for bends of each angle.

Step 6: Add up number of bends for each bend angle.

Step 7: Take number of bends times the B/D.(if different angles, then number of bends of each angle times the B/D forthat angle, add it all up)

Step 8: Shear Size.= (outside dimension in Step 3 ) - (total from step seven)


Page 60 Flat Pattern Development

Example 1Step 1: Dimensions check- this drawing

only has a 90 bend, so the apexand outside dimensions are thesame.

Step 2: Thickness is 0.125

Step 3: Total outside dimensions are1.000 + 2.000 = 3.000

Step 4: Inside radius = 0.500

Step 5: Computed B/D = 0.387

Step 6: Number of bends = 1

Step 7: Total B/D ⇒1 x 0.387 = 0.387

Shear Size ⇒3.00 - .387 = 2.613


Flat Pattern Development Page 61

Acute Angle / ApexIn this example, the dimensions are called out to the Apex of the angle (point“A”). The B/D method is used.

If your print is dimensioned to the edge of the part (dimensions “B”) you caneither:

a. Calculate (using Trigonometry) the position of the Apex, and use the B/Dmethod of Example 1b. Subtract a material thickness and an inside radius to find the tangent dimen-sion (A), then use bend allowance formula to solve (as in example 3).

When a bend is dimensioned to the tangent points (dimensions “A”):Use the bend allowance formula to solve, as in example 3, page 63. For partmeasurement, add a material thickness and an inside radius to find the outsidedimension.

Example 2

Step 1: Dimensions check: angle isdimensioned to apex.Angle is 180 - 70 = 110 degrees.1

Step 2: Thickness is .07"

Step 3: Total outside (apex) dimensionsare 2.5 + 3.5 = 6.000

Step 4: IR = 1.000

Step 5: B/D = 1.076(Formula 4, page 51)

Step 6: Number of bends = 1

Step 7: Total B/D ⇒1 x 1.076 = 1.076

Shear Size ⇒6.000 - 1.076 = 4.924



2.50"

3.50"

A

A

B

B

1.00 R

0.070"

70

1 Note the use of complementary angle here.

Acute Angle / TangentStep 1: This part (Example 3) is dimensioned differently than Example 2. Here, the

dimensions are to the tangent lines, not the apex.

Step 2: Add together the lengths of the flat segments. (from the edges of the part tothe tangent lines.)

Step 3: Determine material thickness.

Step 4: Refer to the B/D, B/A chapter, page 50. Using formula 1, calculate the B/Afor the given conditions.

Step 5: Add the results of Step 2 to the B/A (from step 4) = Shear Size.

Example 3Step 1: Dimensions check : dim to tangent.

Find complementary angle:180 - 70 = 110 degrees

Step 2: flat length ⇒1.500 + .750 = 2.25

Step 3: material thickness = 0.060

Step 4: B/A ⇒1.491

Step 5: Shear Size ⇒2.25 + 1.491 = 3.741



Features in the Flat

To locate a hole or other feature “in the flat”, follow these steps:Step 1: Determine shear size

Step 2: Add OUTSIDE dimensions from edge of part to hole center.(Where dimensions are called out to the inside, be sure to add materialthickness to arrive at outside dimension.)

Step 3: Using the B/D that you used when developing the shear size, add thenumber of bends between the edge of the part and the hole center. TakeB/D times the number of bends.This assumes all bends of same angle and radius. If angle and radius vary,use the B/D computed for each bend.

Step 4: Distance of hole from edge = outside dimension (total from step 2 ) - totalB/D from step 3

Example 4Step 1: (t = 0.056, ir = 0.062, B/D = 0.103)

Shear size ⇒1.647

Step 2: total outside dimension ⇒1.00 + .375 = 1.375

Step 3: B/D x # bends ⇒1 x 0.103 = 0 .103

Step 4: step2 - step3 ⇒1.375 - .103 = 1.272



Thickness = 0.056

Sketching the Layout

An easy way to draw a flat layout is to use mold lines. See the followingdrawing and explanation

Using MOLD LINES

The Mold Lines represent the outside lines of the flanges after they are bent.The distance between each pair of Mold Lines equals one B/D. In the aboveexample flange “A” is represented by dimension “A” on the M/L drawing.Flange “B” and “C” are shown the same way.

Once the M/L are in place, features located anywhere on the blueprint areeasily placed on the M/L drawing.

Each bend line is located midway between the corresponding pair of MoldLines. See “D” above.

A =

B =

C =

Shear Size =



1.008"

0.750"

0.375"

0.254"

1.440"

AB

C

1.000"

Example print

A

B

C

D D

B/D B/D

t = 0.056ir = 0.062B/D = 0.103

Mold Line Drawing

Corner To Corner Notches

When manufacturing a box where a corner-to-corner type construction iscalled for, use this formula for calculating the depth of the notch.

Notch Depth = OUTSIDE flange dimension + material thickness - B/DRelief Hole Diameter = material thickness x 3.Center relief holes on bend lines.

The part shown on page 78 has relief holes and mold lines.



corner-to-corner notch 50% weld notch

Closed notch Relieved notch

Notch Types

Basic Layout Exercises

Use Bend Deduction Charts on pages 48, 49

Exercise 1Solve for the shear size using Drawing 1

Thickness = .056

I.R. = .062

Shear size = __________

Exercise 2Solve shear size for drawing 1using new conditions.

Thickness. = .09

I.R. = .125

Shear size = __________

Exercise 3Solve shear size for Drawing 2.

Thickness. = .059

I.R. = .094

Shear size = __________

Exercise 4Solve shear size for Drawing 2using new conditions.

Thickness = .048

I.R. = .047

Shear size = ___________



4.000”

0.750”

DRAWING 1

1.500”

0.625”

1.250”

DRAWING 2

Exercise 5Use Drawing 3 and solve shear size.

Thickness = .036

I. R. = .031

Shear Size = __________

Exercise 6Solve shear size for drawing 3 usingnew conditions.

Thickness = .074

I. R. = .075

Shear Size =__________

Exercise 7Use Drawing 4 and solve for shear size

Thickness = .056

I. R. = .075

Shear Size =__________

Exercise 8Solve shear size for drawing 4using new conditions.

Thickness = .105

I. R. = .203

Shear Size = _________



1.750”

0.750”

0.875”Typ.

DRAWING 3

2.000”0.500”

typ

0.750”Typ.

DRAWING 4

Class Exercises

Class ExercisesExercise 9:

For Drawing 5, determine “Bend Allowance” then solve for shear size.

Mat. = .125

I.R. = .500

Bend Allowance = ________

Shear Size = ________


Page 72 Class Exercises

DRAWING 5

Exercise 10:Use Bend Deduction formula to solve for shear size in Drawing 6.

Mat. = .125

I.R. = .5

Bend Allowance = ________

Bend Deduction = ________



Class Exercises Page 73

DRAWING 6

Exercise 11:Solve for shear size and hole locationusing Drawing 7.

All dimension called from side “A”.

Mat. = .04

I.R. = .031


Hole 1 = ________

Hole 2 = ________



1.000"

0.031” radius

0.375"

0.750"

0.750"

0.500"

0.250” dia.

0.187” dia.

A

DRAWING 7

Exercise 12:Solve for shear size and hole location for Drawing 8

All Dimension called out from edge A.

Mat. = .059

I.R. = .062


Hole 1 = ________

Hole 2 = ________

Hole 3 = ________

Hole 4 = ________



2.750"

0.250"

1.000"

0.500"

1.500"

0.750"2.000"2 pl.typ.

2 pl.

0.500"

A

1

2 3

4

DRAWING 8



DRAWING 9

An important part of bending is determining a workable bend sequence.Find a workable sequence for Drawing 10.

The letters “A” - “F” on the drawing identify the respective bends.



A BC D

E

F

DRAWING 10

Drawings 11 and 12 show a simple box in the folded and flat conditions. Deter-mine the blank dimensions.



DRAWING 11



dim to center ofrelief hole

dim to center ofrelief hole

DRAWING 12

Bending Sequence


Page 81

Bending SequenceThis chapter illustratesseveral bend profiles andshows a possible sequenceto use in bending eachprofile.

Legend

In the upper illustration,the circled numbers “①”indicate the bend number.The flanges are labelledH1, H2 and so forth.

In the lower illustration, thenumbers following the bendnumber indicate the flangescomprising the distance betweenthe gauge surface and the bendbeing made.

The graphics can be displayed onAmada press brakes equippedwith graphics displays.


Page 84 Bending Sequence

18

18

H1

H2

H3

H4

H5

14.514.5

75°75°

Bending Profile 1

*3

1

* 4

5

Bending Sequence


Bending Sequence Page 85

100

H9

H8

H7H6 18

H5

H4H3

H2

H1

16

43 13.5

25

(165)

Bending Profile 2

1+2+3

4+5

6

*5

*9

*8

2

1

Bending Sequence



Bending Profile 3

Bending Sequence



17.5

12.5

43.5

11.5

21.5

H1

H2

H3H4

H5

H6

12

Bending Profile 4

*6

1

2

*5

3

Bending Sequence

☞ NOTE: Using this bendsequence, the second bendcreates a pinch point.



25 mm

50 mm

20 mm

8 mm

Bending Profile 5

1

1+2

*4

Bending Sequence



Bending Profile 6

Bending Sequence

Exercise Answers1. Shear size = 4.647

2. Shear size = 4.573







9. Bend Allowance = 1.067Shear size = 3.192

10. Bend Allowance = 1.067Bend Deduction = .718Shear size = 4.657

11. Shear size = 1.682Hole 1 = .5Hole 2 = 1.307

12. Shear size = 4.686Hole 1 = .25Hole 2 = .892Hole 3 = 3.794Hole 4 = 4.436

Box SizesBox L = 7.806Box W = 5.806Notch Depth = 0.959Hole Location = 0.951


Page 90 Exercise Answers

SAFETY MEASURES Chapter 2 1/30 OPERATOR’S MANUAL HFE M2 – X41176A Issue 05/2010

2. SAFETY MEASURES


On all machines

Risks of pinching or crushing between tools Risks of plucking or destruction between worksheet and tools during bending. Risks of injuries by sudden movements of the worksheet during bending. Electric danger Refer to the operator’s manual

10/30 Chapter 2 SAFETY MEASURES Issue 05/2010 OPERATOR’S MANUAL HFE M2 – X41176A

2.3. SAFETY PRECAUTIONS 2.3.1. GENERAL POINTS During machine installation, operation, and maintenance, apply all necessary safety measures, and the following in particular: • Do not adjust or service the machine until you have read the manual. • All electrical work must be performed by a qualified and authorized electrician to avoid all

equipment damage or physical injury. • Never place your hands between tools for any reason. • Do not modify the control circuits or any component of the machine. • Never use the machine with any of its safety devices removed or disabled. • Do not enter the safety zone or hazardous area protected by safety device. • Inspect the machine daily before starting work, ensuring that:

- All protective devices are in place. - The free space between the tools is not obstructed. - The access area for the various devices is clear. - The floor around the machine is free of grease, oil, and water.

• Never wear a tie, scarf, or loose clothing when adjusting or operating a press brake.


2.6. PERSONAL PROTECTIVE EQUIPMENTS (PPE) The so-called “Personal Protective Equipments” (PPE) are not included in Amada supplies. You will find below as informative examples the type of Personal Protective Equipments possibly required on our machines:

• gloves, • helmets, • ear guards, • goggles, • safety shoes, • etc.

the user of these so-called PPE should check that they fully comply with the European directive. The employer is obliged to:

supply the appropriate PPE, ensure that the appropriate PPE are selected with regards to the risks involved, ensure that the employee is using them efficiently, ensure their compliance with the regulation, inform people who are responsible for the implementation (work shop manager,

foremen, etc.), ensure the PPE are in perfect working condition and periodic maintenance is

carried out, inform users which potential risks are protected by the use of PPE, train and lead users in the regular use of PPE.


Figure 2.12

Figure 2.13


2.7. RULES FOR SAFE OPERATION Release the part to be bent as soon as it is gripped between tools (Fig. 2.12).

Install or remove the tools in full compliance with the procedure described in the

Operator’s Manual (§ 7.5) and/or the recommendations specific to your tooling. (Fig. 2.13).

To avoid damage to your tooling or any accident, Amada urge you to follow strictly the procedure below :

• Every time you change a program, select adjustment mode and mute stop.

• Carryout a dry cycle • Check visually that all parameters correspond to the tooling

mounted on the machine, the mute point is 6 mm above sheet pinch point and the end of bend is correct.

• Switch to normal cycle.

CAUTION: Handling devices for heavy parts are not included in the Amada supplies. They must be installed for risk-free use in accordance with ergonomic principles.


Figure 2.14

Figure 2.15

Figure 2.16


Never attempt to support the end of the worksheet by holding it on either side of the tools. Only install the tool length required for the current job on the machine (Fig. 2.14).

Never place your hand between the worksheet and the backgauge during operation (Fig. 2.15).

Never place your part against/over the backgauge finger before backgauge is positioned on programmed position.

No part of your body must enter the hazardous area during bending operations (Fig. 2.16).


Figure 2.17

Figure 2.18


Beware of sudden movements of the worksheet during bending (Fig.

2.17).

Observe the allowable tool load (Fig. 2.18 and § 7.5). Par example : - 1,2 T/cm for standard punches, except: - 1,5 T/cm for heavy punches - 0,5 T/cm for punches with extra thin blades

(1 T = 10 kN) The specific value for each tool type is shown in the special Tooling catalogue (AMADA or equivalent).


Figure 2.19

Figure 2.20


The dutch bending or hemming tool should be firmly secured to the lower beam (Fig. 2.19). This type of tooling shouldn’t be used on “High Speed” press brakes i.e. where working speed can reach 20 mm/s.

Never hold the sheet by its folded edge; hold it from the sides (Fig. 2.20).

Manual de Teoria Amada Press Brake

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