Chapter 1 Introduction 1

Chapter 1

Introduction

1.1 Introduction to Bending:-
Bending of sheet metal is a common and vital process in manufacturing industry. Sheet metal bending is the plastic deformation of the work over an axis, creating a change in the part’s geometry. Similar to other metal forming processes, bending changes the shape of the work piece, while the volume of material will remain the same. In some cases bending may produce a small change in sheet thickness. For most operations, however, bending will produce essentially no change in the thickness of the sheet metal. In addition to creating a desired geometric form, bending is also used to impart strength and stiffness to sheet metal, to change a part’s moment of inertia, for cosmetic appearance and to eliminate sharp edges.

Fig. 1 Introduction To Bending

1.2 Project Statement:-
We going to KPTL company Gandhinagar. This is company have large production plant house. We visit the bending department in production plant. We saw very large and small scale bend machine horizontal as well as vertical.
We saw vertical press bend machine which have V-die and v-punch. The workers are make U-bend by V-die. We saw that there are many problems created in V-die and punch.
We observed that and understand the problem.We decide to use U-die and punch instead of V-die and punch.

1.3 Overview of Problems :-

1. Difficult to predict bend-up line.
2. Springback chances are more.
3. After make bend the two sides of leg length are not equal in height.
4. After the bend operation the two sides of holes are not in coecentric.
5. The precise hole position is not sure after bending.
6. The bending surface is thinner.
7. Double time make up the bend .
8. Punch moves downward two times then force required more. Punch movement is more.
9. Set-up time is more.

1.4 Objectives:-

1. Know the basics of sheet metal working.
2. Familiarise yourself with various sheet metal working operations.
3. Understand principles of die and punch design.

Chapter 2

Literature Review

2.1 Introduction:-
This chapter will discuss about the types of bending and material. It also discuss about meaning of springback, yield point and ultimate tensile strength. Bending, springback and related equations are among the interested terms in this chapter. The source from literature review is from journals, articles and books. Literature review is done to provide information about previous research and that can help to smoothly run this project.

2.2 Theory of sheet metal bending:-
A process by which metal can be deformed by plastically deforming the material and changing its shape is called bending. The material is stressed beyond the yield strength but below the ultimate tensile strength. The surface area of the material does not change much. Bending usually refers to deformation about one axis.
Bending is a flexible process by which many different shapes can be produced. Standard die sets are used to produce a wide variety of shapes. The material is placed on the die, and positioned in place with stops and or gages. It is held in place with hold-downs. The upper part of the press, the ram with the appropriately shaped punch descends and forms the shaped bend.

2.3 Type Of Bending Process for U-bend :-
A bending tool must be decided depending on the shape and severity of bend. Following are the different types of bending commonly used for precision sheet metal bending.

2.3.1 U” Bending:-
Punch and die are manufactured with certain geometries, in order to perform specific bends. Channel bending uses a shaped punch and die to form a sheet metal channel. A U bend is made with a U shaped punch of the correct curvature.

Fig. 2 U – Bending Model
2.3.1.1 Review:- From http://www.custompartnet.com/wu/sheet-metal- forming#bending
Based on literature review and research paper find the conclusion. This is simple and fast method for make u- bend workpiece.Also required less effort to make job.

2.3.2 “Edge” Bending:-

Edge bending is another very common sheet metal process and is performed with a wiping die. Edge bending gives a good mechanical advantage when forming a bend. However, angles greater than 90 degrees will require more complex equipment, capable of some horizontal force delivery. Also, wiping die employed in edge bending must have a pressure pad. The action of the pressure pad may be controlled separately than that of the punch. Basically the pressure pad holds a section of the work in place on the die, the area for the bend is located on the edge of the die and the rest of the work is held over space like a cantilever beam. The punch then applies force to the cantilever beam section, causing the work to bend over the edge of the die.

Fig 3 Edge Bending Model
2.3.2.1 Review: From http://www.custompartnet.com/wu/sheet-metal-forming#bending

Based on literature review and research paper find the conclusion. This is very complex and time consuming method.This method is very costly and use make specific job.

2.3.3 “V” Bending:-
One of the most common types of sheet metal manufacturing processes is V bending. The V shaped punch forces the work into the V shaped die and hence bends it. This type of process can bend both very acute and very obtuse angles, also anything in between, including 90 degrees.

Fig. 4 V- Bending Model

2.3.3.1 Review:- From http://www.custompartnet.com/wu/sheet-metal- forming#bending

Based on literature review and research paper find the conclusion. This is very chip , time consuming, and difficult method for make bend. This method required more affort then above two method.

Chapter 3

Methodology

3.1 Bending Process Description:-

Fig .1 Terminology

Bend Allowance – The length of the arc through the bend area at the neutral axis.

Bend Angle – The included angle of the arc formed by the bending operation,

K-factor – Defines the location of the neutral axis. It is measured as the distance from the inside of the material to the neutral axis divided by the material thickness.
Neutral Axis – Looking at the cross section of the bend, the neutral axis is the theoretical location at which the material is neither compressed nor stretched.

Set Back – For bends of less than 180 degrees, the set back is the distance from the bend lines to the mold line.

3.2 2D Model For U-die And Punch:-

fig. 2 2D Model

3.3 3D Model of Die And Punch :-

Fig. 3 3D Model

Chapter 4

Design Of Die And Punch

4.1 Properties of HT material:-

SI
No.

Origin
High Tensile Steel

No. of
standard
Ultimate
Tensile
Stress
Kg/mm2 Minimum
Yield
Stress
Kg/mm2 Minimum
Elongation
%

1.
India IS : 961
1975 58 36
20
2.
USSR
CLT5
20L2 50-62
28
15-21

33. 3.
Italy
UNI
50-60
34-38
22

4.
UK BS : 548 1934
1934 58-68 30-36 14
Table 1. Properties of material
4.2 Data of Flate plate:-

1. Thickness of sheet (t) 10 mm
2. Length of sheet (l) 488 mm
3. Width of sheet (b) 331 mm
4. Inside Band Radius (ri) 15 mm
5. Outside Band Radius (ro) 20 mm
6. Constant (k) 0.33 when 2t > ri
0.5 when 2t < ri
7. Die Opening Factor (K) 0.67
8. Ultimate Tensile Strength (?) 58 Kg/mmˆ2
9. Bend Angle (?) 90 Degree
10. Material of Plate HT

Table 2. Data of workpiece

4.3 Design Data Of Die:-

Die radius at edge (Rd) 20 mm
Die length (Ld) 210 mm
Die width (Wd) 340 mm
Die Height (Hd) 150 mm
Die Inside Radius (Ri) 20 mm

Table.3 Design data of die

4.4 Design Data Of Punch:-

Punch radius at edge (Rp) 15 mm
Punch length (Lp) 190 mm
Punch Height (Hp) 139 mm
Punch Width (Wp) 335 mm

Table 4. Design data of punch

4.5 Calculation For U-Bend:-

4.5.1 Bend Allowances:-
The Bend Allowance(BA) is the length of the arc of the neutral line between the tangent points of a bend in any material. Adding the length of each flange taken between the center of the radius to the BA gives the Flat Pattern length. This bend allowance formula is used to determine the flat pattern length when a bend is dimensioned from 1) the center of the radius, 2) a tangent point of the radius or 3) the outside tangent point of the radius on an acute angle bend..
Fig. 8 Bend Allowances

BA = 2 × ? × ? (r + kt) ÷ 360
B A = 2×3.14×90×(15+0.33×10) ÷ 360
BA = 10343.16 ÷ 360
BA = 28 mm

4.5.2. Total Length Of Blank (L) :-
The total length of blank is sum of all the length and bend allowance.

L = Leg length 1 + Leg length 2 + Leg length 3 + Bend Allowance
L = 135 + 190 +135 + 28
L = 488 mm

4.5.3 Span (W) :-
It is the summation of radius of punch at edge , radius of die at edge and clearance between punch and die.

W = Radius at punch edge + Radius at die edge + Clerance
W = 15 mm + 20 mm + 10mm
W = 45 mm

4.5.4 Clearance (C):-
It is distance between die and punch.It is very important design parameter for both die and punch.. It is necessary to correct clearance between them. If correct clearance no provided then wear and tear effect formed both of them and they go to break and fail.

Fig. 9 Clearance

Total Die clearance (C) = Die clearance both sides of Punch
C = 10 + 10
C = 20 mm

4.5.5 Bending Force (FB) :-
Bending is a forming operation in which a sheet metal is subjected to bending stress thereby a flat straight sheet is made into a curved sheet. The sheet gets plastically deformed without change in thickness. If a U shaped die and punch are used, the bending is called U-bending.

Fig. 10 Benging force model

Required Bending force is :-
FB = K × L × ? × t ˆ2 ÷ W
FB = 0.67 × 135 × 58 × 10 × 10 ÷ 45
FB = 11658.2 kg

4.5.5 Velocity (V):-
The punch is travel from its upper position to in die .The distance travel by punch upper position to die with time . The velocity ratio of distance travel by punch by taken time to reach time called velocity.

Velocity (V) = Distance travel by punch ÷ Take time to reach

Distane = 600 mm = 0.6 m
Time = 10 sec

Velocity (V) = 0.6m ÷ 5 sec
V = 0.12 m/sec

4.4.7 Power Consumption (P):-
The total power required to operate all machine tool. . Power consumption calculated by multiplication of bending force and Velocity of punch.

(P) = Bending Force × Velocity
P =. 11658.2 × 0.12
P = 1400.98 Watt
P = 1.4 kw

4.6 Calculation Of V-Bend:-

Fig. 11 V-bend Diagram

1. Sheet thickness (t) 10 mm
2. Die opening (w) 150 mm
3. Width of bending (w) 331 mm
4. Ultimate Tensile strength (?) 58 N/mmˆ2
5. Die opening factor (K) 1.33

Table 5. data of v-bend

4.6.1 Bending force (FB) :-
Bending is a forming operation in which a sheet metal is subjected to bending stress thereby a flat straight sheet is made into a curved sheet. The sheet gets plastically deformed without change in thickness. If a V shaped die and punch are used, the bending is called V-bending.

(FB) = K × ? × w × (tˆ2) ÷ D
FB = 1.33 × 58 × 331 × 10 × 10 ÷ 150
FB = 17022.22 kg

4.6.2 Velocity (V) :-
The punch is travel from its upper position to in die .The distance travel by punch upper position to die with time . The velocity ratio of distance travel by punch by taken time to reach time called velocity.
Velocity (V) = Distance travel by punch ÷ Take time to reach
Distane = 600 mm = 0.6 m
Time = 10 sec

V = 0.6 m ÷ 5 sec
V = 0.12 m/sec

4.6.3 Power Consumption (P) :-
The total power required to operate all machine tool . Power consumption calculated by multiplication of bending force and Velocity of punch.

(P) = Bending Force × Velocity
P = 17022.22 × 0.12
P = 2002.66 watt
P = 2.0 Kw

Chapter 5

Result

• From above calculation we see that the power consumption of of old method and new method are:-
U-die and Punch = 1.4 kw
V-die and punch = 2.0 kw
• In V-die there are two times and two sides bend make. So power requirement is two times.
• So , power requirement of old method comparatively more then U-die.

Chapter 6

Process Of Operation

• The flate plate is heated in electric burner at temperature range is between 500 ?C to 700?C around 10 minute . So, the flat sheet is become soft and plasticity formed . So easily worked on it. Heating is carried out for the purpose of plastic deformation of plate to get die shape.

• After that its become plasticity form it is removed from chimney and puts on die at its correct position. And it is fixed with some tool like hook , striper , etc.

• The punch go to downward movement towards die with velocity and force to make the workpiece shape as per die shape.

• The heated plate is already soft so when the punch push it in the die . So its on desired shape.

• After the workpiece taken shape as per die shape the punch remove from die and go upward direction to it’s position.

• The workpiece pull from die with help of some tool.

• After that the workpiece become cool and take its final shape.

Chapter 7

Advantages

• Easy assamble and dissemble.

• Set up time is less.

• easy to operate.

• Less effort by workers.

• fast and easy mwthod for produce work

• Springback reduced.

• Easy maintain.

• Less maintenance cost.

Chapter 8

Progress During Project

• Brief research on die and punch design in U – die bend machine.

• Measure V- die and punch dimension for making u-bend.

• Dissemble V-Die and make new U-die for make u–bend.

• Calculate all the dimension of punch and Die which is required.

• Measure force and power consumption for bend the plate.

• Compare the variation of old system and new system.

• Check this new system reliable or not.

Chapter 9

Challenges Faced During Project

• .Disassemble problem due to inherence of the components.

• Measuring problem due to wear and tear on the components.

• Problem in disassemble due to complicated design of the machine.

• Measure Dimensions of all parts and implement.

• Heating Problem on plate. Some time its become very soft and sometimes its not become soft.

• Edge bulging happens when the bend on outside of the sheet is
stretched and inside compressed.

• Due high pressure the thickness of sheet reduced.

Chapter 10

SetUp Of Vertical Press Bend Machine

Fig. 12 Setup of press mahine
Chapter 11

Conclusion

In course of this project I have gained a great deal of confidence and knowledge in the way of job manufacturing. The work has gone in detail in all the analysis methodically. The tool can also be designed and
manufactured without any these analyses, but the success and the economics of the tool is not assured.
I have executed my very best to achieve the required results, as far as the tool is concerned. This project has paved a new way for me to tap the knowledge that lies in the waste field of Press tools.
I learned many aspects such as co-operating and adjusting myself with other fellow crew working on this design. And the strong positive guidance given by our guides during solving of problems is really commendable; hence the success of the design analysis of the die and punch is assured.

Chapter 12

Future Scope

• Replacing in design will be beneficial in increasing the
Productivity of job.

• It will help to reduce the lead time in manufacturing.

• It will also help in mass production without any extra power
consumption.

• It is required less effort by the workers.

Chapter 13

References

• http://www.custompartnet.com/wu/sheet-metal-forming#bending

• https://www.machinemfg.com/sheet-metal-bending-solutions/

• F., M. (August 2008), ;Press BrakeBending: Methods and Challenges; (PDF),Metalforming: 38–43, archived from the original (PDF) on 2011-07-14.

• Mc hill ;die design data book; 2nd edition

• https://nptel.ac.in/courses/Webcourse-contents/IIT-ROORKEE/MANUFACTURING-PROCESSES/Metal%20Forming%20;%20Powder%20metallurgy/lecture6/lecture6.html

• Design and Manufacturing of U-Bending Tool to Overcome Spring Back Effect by Ironing Impact
https://www.ijirset.com/upload/2017/tapsa/24_production_009_New PDF
Journal of Innovative Research in Science, Engineering and Technology
Manjunathan.R1*, Mohanraj.R1, Moshay.M1, Natchimuthu.N1,
Suresh.S2 ISO 3297: 2007 Certified Organization Volume 6, Special Issue 7, April 2017

• ;Bending problems and solution;
https://www.fsmdirect.com/bending-folding/129-bending-plate

• You-Min Huang, 2005, ;Influence of blank profile on the V-die bending camber process of sheet metal;, Int J Adv Manufacturing Technology, Vol. 25, pp. 668-677. www.scielo.br/scielo.php?script=sci_nlinks;ref=000228;pid=S1678-5878201100010000700015;lng=en

• X. Z. Feng et al., ;Forming Analysis and Die Design for the Bending Die for U Type Parts;, Advanced Materials Research, Vols. 181-182, pp. 1038-1043, 2011
https://www.scientific.net/AMR.181-182.1038