design and development of single point incremental sheet

4
5 th International & 26 th All India Manufacturing Technology, Design and Research Conference (AIMTDR 2014) December 12 th –14 th , 2014, IIT Guwahati, Assam, India 94-1 Design and Development of Single Point Incremental Sheet Forming Machine *Yogesh Kumar 1 , Santosh Kumar 2 1&2 Mechanical Engineering Department, Indian Institute of Technology (BHU), Varanasi (UP), India, 221005 E--Mail: 1 [email protected], 2 [email protected] Abstract Single Point Incremental Sheet Forming (ISF) is one of the most advanced techniques in the domain of flexible sheet forming process to produce complex products, which do not require any expensive and dedicated forming tools (punch & die). The Laboratory setup of Incremental Forming Machine has been developed. A Motion card has been used to control the 3 servo motors giving capability of individual 3 Axis controlling. The forming trials are carried out based on simulation study of incremental forming process. The strain distribution over the length of deformation has been computed. Keywords: Incremental Sheet forming, Dieless forming, Modeling, Simulation etc. 1 Introduction & Literature Review Incremental sheet forming is a new technique for deforming sheet metals by the application of step by step incremental feed to the deforming tool. For the production of parts by conventional sheet forming techniques dedicated tools are required. The dedicated tools are complex in design and thus are expensive. The design of tooling (die and punch) for complicated shapes is difficult and expensive. In Incremental forming technique, only a deforming tool is required for deforming the sheet metals. There are four major elements of incremental sheet forming as shown in Fig. 1: (i) a sheet metal blank, (ii) a blank holder, (iii) a single point forming tool or deforming tool, (iv) CNC Machine. Figure 1: Basic Elements of Incremental Dieless Sheet Forming [Y. Kumar et. al., 2013]. The main element of incremental forming process is deforming Tool (DT). This is a hemi-spherical in shape, so its design is quite simple and economic. A three axis CNC Machine is generally used to control the movements of the deforming tool. The path of forming tool is optimized and a free run is taken before going to actual deformation of the sheet metal for ensuring the proper deformation of sheet. In Incremental Sheet Forming (ISF) specific terminologies are used as seen in Fig. 2, with definitions below: Figure 2: SPIF Terminology in ISF [Ham et. al. 2007]. . . . . The incremental step-down size (step size, Δz) is the amount of material deformed for each revolution of the forming tool (similar to depth of cut in machining). The step size affects the machine time and the surface quality. The step size parameter is set in CAM software. Feedrate is the speed of forming tool moves around the mill bed (similar to cut rate in machining). The federate had a direct impact on the machine time for forming. It is measured in mm/minute. The federate parameter is set in CAM software and is then varied on the mill. The spindle

Upload: others

Post on 31-Oct-2021

4 views

Category:

Documents


0 download

TRANSCRIPT

Page 1: Design and Development of Single Point Incremental Sheet

5th International & 26th All India Manufacturing Technology, Design and Research Conference (AIMTDR 2014) December 12th–14th, 2014,

IIT Guwahati, Assam, India

94-1

Design and Development of Single Point Incremental Sheet

Forming Machine

*Yogesh Kumar1, Santosh Kumar2

1&2Mechanical Engineering Department, Indian Institute of Technology (BHU), Varanasi (UP), India, 221005

E--Mail: [email protected], [email protected]

Abstract

Single Point Incremental Sheet Forming (ISF) is one of the most advanced techniques in the domain of flexible

sheet forming process to produce complex products, which do not require any expensive and dedicated forming

tools (punch & die). The Laboratory setup of Incremental Forming Machine has been developed. A Motion card

has been used to control the 3 servo motors giving capability of individual 3 Axis controlling. The forming trials

are carried out based on simulation study of incremental forming process. The strain distribution over the length

of deformation has been computed.

Keywords: Incremental Sheet forming, Dieless forming, Modeling, Simulation etc.

1 Introduction & Literature Review

Incremental sheet forming is a new technique for

deforming sheet metals by the application of step by

step incremental feed to the deforming tool. For the

production of parts by conventional sheet forming

techniques dedicated tools are required. The dedicated

tools are complex in design and thus are expensive.

The design of tooling (die and punch) for complicated

shapes is difficult and expensive. In Incremental

forming technique, only a deforming tool is required

for deforming the sheet metals. There are four major

elements of incremental sheet forming as shown in

Fig. 1: (i) a sheet metal blank, (ii) a blank holder, (iii)

a single point forming tool or deforming tool, (iv)

CNC Machine.

Figure 1: Basic Elements of Incremental Dieless

Sheet Forming [Y. Kumar et. al., 2013].

The main element of incremental forming process

is deforming Tool (DT). This is a hemi-spherical in

shape, so its design is quite simple and economic. A

three axis CNC Machine is generally used to control

the movements of the deforming tool. The path of

forming tool is optimized and a free run is taken

before going to actual deformation of the sheet metal

for ensuring the proper deformation of sheet.

In Incremental Sheet Forming (ISF) specific

terminologies are used as seen in Fig. 2, with

definitions below:

Figure 2: SPIF Terminology in ISF [Ham et. al. 2007].

�� � ������� ���� ��� ���.

�� � ����� ���� ��� ���.

∆� � �� �������� ��� � ���� ���.

� � ���� ����� �� ������� �����.

The incremental step-down size (step size, ∆z) is

the amount of material deformed for each revolution

of the forming tool (similar to depth of cut in

machining). The step size affects the machine time

and the surface quality. The step size parameter is set

in CAM software. Feedrate is the speed of forming

tool moves around the mill bed (similar to cut rate in

machining). The federate had a direct impact on the

machine time for forming. It is measured in

mm/minute. The federate parameter is set in CAM

software and is then varied on the mill. The spindle

Page 2: Design and Development of Single Point Incremental Sheet

Design and Development of Single Point Incremental Sheet Forming Machine

94-2

rotation speed is the speed at which the tool rotates.

The spindle rotation speed varies the heat generated at

the contact point between the material and the

forming tool. The spindle rotation speed is also set at

the mill. The angle between the horizontal, un-

deformed sheet metal and the deformed sheet metal is

defined as the draw angle or forming angle (φ) as

shown in Fig. 2. The forming angle can be used as a

measure of material formability. The maximum angle

(φmax) is the greatest angle formed in a shape without

any failures. The forming angle is set within CAD

software [Ham et. al. 2007]. A summary of recent

literature done by Y. Kumar and S. Kumar has been

represented in Table 1.

Table 1: Recent Literature Review [Y. Kumar et. al., 2013]

S.N. Issue Research Highlights

1 Classification

Single Point Incremental Forming SPIF

Two Point Incremental Forming, TPIF

Two Point Incremental Forming with Partial Die

Two Point Incremental Forming with Full Die

2 Formability

The formability of sheet metal appears better than conventional forming.

Double-forming technique improves formability.

The deformation occurs due to plane-strain and bi-axial stretching.

The forming limit curve is expressed as a straight line with a negative

slope.

Depth and diameter have no effect.

3

Surface Quality and

Geometric

Accuracy

In hot incremental forming the quality of bottom surface is better as

compared to the one in contact with the punch.

Some errors along the oblique walls

Elastic spring back causes geometric inaccuracy.

The results of process model and experimental results are approximately

same.

4 Deforming Force

and Sheet Thinning

The forming forces depend on tool path.

The forming force is slightly lower than the experimental values.

Sheet thinning depends on the wall angle α.

Sheet thinning is given by the sign law t1 = t0 sin (90° - α)

Thickness measurements with the process model and experimental results

obtained are approximately same.

2 DEVELEOPMENT OF MACHINE

SETUP The major elements of incremental sheet forming

are identified as : (i) a sheet metal blank, (ii) a blank

holder, (iii) a single point forming tool or deforming

tool, (iv) CNC Machine. The path of the deforming

tool is responsible for the shape, size and accuracy of

the final product. Thus the quality of the product

depends on the proper tool path planning. The

development of different parts of incremental forming

Machine has been discussed as below:

2.1 Sheet Metal Blank The Incremental forming Machine is basically

used for deforming product from metals sheets. The

current research is mainly focused on the

development of incremental sheet forming process for

light alloy. The Material for metals sheet can be

Aluminium alloys, Brass, Titanium alloys etc. For

testing the Machine Developed at IIT (BHU,) a brass

sheet of blank size 100mm*100mm*0.5mm has been

used for current experimental study. The sheet has

been deformed using incremental forming machine

and a finished product as shown in Fig. 5 was

obtained.

The shape, size and accuracy of the finished

product are compared with the simulation model. The

shape and size of the processed model as compared to

the simulation model has been found approximately

same.

2.2 Blank Holder or Blank Holding Arrangement Blank holder is the most important element of the

incremental forming machine. The proper blank

holding arrangement is necessary for properly holding

the blank sheet. A CAD model of the blank holding

arrangement as shown in Fig. 3 was developed for

simulation study. Also based on the simulation study

a modified blank holding arrangement and a single

point Incremental Forming Machine has been

developed as shown in Fig. 4. The metals as well as

alloys can be deformed easily by incremental sheet

forming process. For the current investigations the

initial blank of brass is selected for finding the

capabilities of incremental sheet forming process

Page 3: Design and Development of Single Point Incremental Sheet

5th International & 26th All India Manufacturing Technology, Design and Research Conference (AIMTDR 2014) December 12

IIT Guwahati, Assam, India

because brass is having good formability at room

temperature.

Figure 3: CAD Model of Blank and Blank holding

Arrangement.

Figure 4: Single Point Incremental Forming Machine

2.3 Single Point Forming Tool or Deforming ToolThe single point forming tool also known as

Deforming Tool is another major element or most

important element of the incremental forming

machine. The Deforming tool may be spherical or

elliptical or conical in shape. For the current

a conical tool, having hemispherical shape at tip h

been used as shown in Fig. 4.

2.4 CNC Machine The CNC Machine is needed in order to control

the tool path. A Motion card having capability of

controlling 8 independent axis has been used. A 3

Axis in house CNC machine has been developed for

controlling the tool path.

3 RESULT AND DISCUSSION

The Single point incremental forming is capable in

producing 3D complex components. The success of

this process depends on mainly on Tool path.

In deforming sheets by Incremental forming,

Methodology of deformation plays an important role.

All India Manufacturing Technology, Design and Research Conference (AIMTDR 2014) December 12

ormability at room

Blank and Blank holding

Single Point Incremental Forming Machine.

Single Point Forming Tool or Deforming Tool The single point forming tool also known as

major element or most

incremental forming

The Deforming tool may be spherical or

cal in shape. For the current research

, having hemispherical shape at tip has

The CNC Machine is needed in order to control

A Motion card having capability of

xis has been used. A 3

has been developed for

RESULT AND DISCUSSION

The Single point incremental forming is capable in

producing 3D complex components. The success of

this process depends on mainly on Tool path.

In deforming sheets by Incremental forming,

Methodology of deformation plays an important role.

In order to adopt a suitable forming methodology, a

recent survey by Y. Kumar and S. Kumar

the area of Incremental forming has been kept into

consideration as shown in Table 1.

Figure 5: Defect free product

For the successful implementation of ISF, a proper

forming methodology has to be followed as shown in

Fig. 6. The first step in ISF is to identify need for the

components. As soon as the need analysis is done the

geometrical dimensions of the product to be

manufactured, are decided. Based on geometrical

dimensions a 3D CAD model of the product is

developed using CAD/CAM package. Moving

forward with the help of CAD/CAM package, the tool

path¸ suitable for movement of the tool is generated.

In the next step the workpiece is held in the proper

blank holding, and test pieces are produced using the

generated tool path. The accuracy of test pieces is

tested against the desired profile.

Figure 6: Forming methodology

In order to investigate the strain distribution in the

deformed product the grid pattern was prepared on the

bottom surface of sheet as shown in figure having

resolution of 1mm. The metal sheet was divided into

the 5 portions. Each portion is having 5 grids i.e. 5

All India Manufacturing Technology, Design and Research Conference (AIMTDR 2014) December 12th–14th, 2014,

94-3

In order to adopt a suitable forming methodology, a

recent survey by Y. Kumar and S. Kumar (2013) in

the area of Incremental forming has been kept into

(Brass).

For the successful implementation of ISF, a proper

o be followed as shown in

. The first step in ISF is to identify need for the

components. As soon as the need analysis is done the

geometrical dimensions of the product to be

manufactured, are decided. Based on geometrical

dimensions a 3D CAD model of the product is

developed using CAD/CAM package. Moving

D/CAM package, the tool

path¸ suitable for movement of the tool is generated.

In the next step the workpiece is held in the proper

blank holding, and test pieces are produced using the

generated tool path. The accuracy of test pieces is

Forming methodology in ISF.

In order to investigate the strain distribution in the

deformed product the grid pattern was prepared on the

bottom surface of sheet as shown in figure having

The metal sheet was divided into

the 5 portions. Each portion is having 5 grids i.e. 5

Page 4: Design and Development of Single Point Incremental Sheet

Design and Development of Single Point Incremental Sheet Forming Machine

mm in length. The cone (Top circle radius R = 20

mm, Bottom circle radius = 5 mm).

Figure 7: Grid pattern on the Bottom surface.

For the analysis of strain distribution in the sheet

deformed by incremental forming process the

following 5 regions were identified on the deformed

sheet:

Region A: Starting from centre point (Point 1) of

bottom circle next 5 grids (Point 2) were identified as

the region A.

Region B: Starting from Point 2 of next 5 grids i.e.

upto Point 3 were identified as the region B.

Region C: Starting from Point 3 of next 5 g

upto Point 4 were identified as the region C.

Region D: Starting from Point 4 of next 5 grids i.e.

upto Point 5 were identified as the region D.

Region E: The portion beyond Point 5 was identified

as the region E.

The Strain was found to be distributed normally over

the length of deformation as shown in fig. 8.

(a) Strain Distribution

0

0.2

0.4

0.6

0.8

A B C D

Development of Single Point Incremental Sheet Forming Machine

mm in length. The cone (Top circle radius R = 20

: Grid pattern on the Bottom surface.

r the analysis of strain distribution in the sheet

deformed by incremental forming process the

following 5 regions were identified on the deformed

: Starting from centre point (Point 1) of

bottom circle next 5 grids (Point 2) were identified as

: Starting from Point 2 of next 5 grids i.e.

upto Point 3 were identified as the region B.

: Starting from Point 3 of next 5 grids i.e.

upto Point 4 were identified as the region C.

: Starting from Point 4 of next 5 grids i.e.

upto Point 5 were identified as the region D.

: The portion beyond Point 5 was identified

ted normally over

the length of deformation as shown in fig. 8.

(b) Normal plot

Figure 8: Strain Distribution

4 CONCLUSION

The incremental forming process is a flexible

forming process and it can be easily used for

producing 3D complex shapes. The process can be

used for larger forming angles with proper forming

methodology. The Laboratory setup of Single Point

Incremental Sheet Forming Machine has been

developed using Motion card to control the 3 servo

motors giving capability of individual 3

controlling. The defect free product of brass

produced using the ISF. The strain distribution over

the length of deformation has been computed

strain distribution in ISF has been found to be

distributed over the length of the deformation.

this process has a larger scope for producing complex

shapes. A proper attention is to be paid on forming

methodology and tool path.

References

1. Ham, M., and J. Jeswiet. "Forming Limit Curves

in Single Point Incremental Forming."

Annals - Manufacturing Technology

(2007): 277–280.

2. Ham, M., and J. Jeswiet. "Single Point

Incremental Forming and the Form

for AA3003." CIRP Annals -

Technology 55, no. 1 (2006): 241

3. Kumar, Y., and S. Kumar. "Incremental Dieless

Forming of Sheet Metals: A Short Review."

International Journal of Mechanical

Engineering Research 3, no. 1 (February 2013):

01-04.

4. Kumar, Y., and S. Kumar.. "Micro

Sheet Forming (µ-ISF)." Proceedings of

National Symposium on Miniature

Manufacturng in 21st Century .

E

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

Strain Distribution Curve

D C B A

94-4

Strain Distribution

The incremental forming process is a flexible

forming process and it can be easily used for

producing 3D complex shapes. The process can be

used for larger forming angles with proper forming

The Laboratory setup of Single Point

Machine has been

otion card to control the 3 servo

giving capability of individual 3-Axis

The defect free product of brass has been

The strain distribution over

tion has been computed. The

strain distribution in ISF has been found to be

distributed over the length of the deformation. Thus,

this process has a larger scope for producing complex

shapes. A proper attention is to be paid on forming

Ham, M., and J. Jeswiet. "Forming Limit Curves

in Single Point Incremental Forming." CIRP

Manufacturing Technology 56, no. 1

Ham, M., and J. Jeswiet. "Single Point

Incremental Forming and the Forming Criteria

Manufacturing

55, no. 1 (2006): 241-244.

Kumar, Y., and S. Kumar. "Incremental Dieless

Forming of Sheet Metals: A Short Review."

International Journal of Mechanical

3, no. 1 (February 2013):

. "Micro-Incremental

Proceedings of

National Symposium on Miniature

Manufacturng in 21st Century . 2013. 267-284.

Strain Distribution Curve

E