Challenge

Week 4- Rolling operation

DDharmesh Joshi14 Oct 2020

Introduction

In metalworking, rolling is a metal forming process in which metal stock is passed through one or more pairs of rolls to reduce the thickness and to make the thickness uniform. The concept is similar to the rolling of dough. Rolling is classified according to the temperature of the metal rolled. If the temperature of the metal is above its recrystallization temperature, then the process is known as hot rolling. If the temperature of the metal is below its recrystallization temperature, the process is known as cold rolling. In terms of usage, hot rolling processes more tonnage than any other manufacturing process, and cold rolling processes the most tonnage out of all cold working processes. Roll stands holding pairs of rolls are grouped together into rolling

Mills that can quickly process metal, typically steel, into products such as structural steel (I-beams, angle stock, channel stock), bar stock, and rails. Most steel mills have rolling mill divisions that convert the semi-finished casting products into finished products.

Working principle of the rolling process:

In the rolling process, stock of material is passed between one or more pairs of rollers in order to reduce and to maintain the uniform thickness. This process mainly focused on the cross-section of the ingot or metal to be pressed which aid the reduction of the workpiece thickness. Rolling processes increases the length and the decreases the thickness without changing the width of the material.

Types of Rolling Process:

Ring Rolling
Roll Bending
Roll Forming
Profile Rolling
Controlled Rolling

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Analysis

Here we will see Structural Analysis for Rolling Copper Operation.

In which we will put a Copper Rod between two Rolls and extract the sheet form of Copper metal.

Here material will be Copper Alloy NL.

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Geometry:

In geometry, there are two Roll Wheels and one Workpiece as shown in below image.

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Material Specifications:

Copper Alloy NL

Density: 8300 Kg/m³

Young’s Modulus: 1.1 E+05 MPa

Poisson’s Ratio: 0.34

Yield Strength: 280 MPa

Tangent Modulus: 1150 Mpa

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Mesh:

Details:

Global Element Size: Default
Body Sizing : Workpiece

Element Size = 1.35 mm

Face Sizing : Wheel_1 & Wheel_2

Element Size = 2.5 mm

No. of Nodes: 31069
No. of Elements: 5953

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Procedure:

Import model in Static Structural named as “Skill_Lync_Copper_Rolling.stp” in Geometry section.
Change in the geometry as follows:
Increase length of Copper Workpiece by 60 mm.
Decrease width of Copper Workpiece by 8 mm.

We can see that final thickness of Copper rode has been 9 mm.
Then go to Mechanical model section.
Rename Roll Wheels and Copper rod as Wheel_1, Wheel_2 and Workpiece as shown above in geometry.

Connections:

Delete automatically created contacts and create new contacts as given below:

Contact_1:

Contact Body = WORK_PIECE

Target Body = WHEEL_1

Contact_2:

Contact Body = WORK_PIECE

Target Body = WHEEL_2

Settings for both Contacts:

Type: Frictional
Friction Coefficient: 0.2
Formulation: Augmented Lagrange
Normal Stiffness : By factor
- Normal Stiffness Factor: 0.1
Update Stiffness: Each Iteration
Interface Treatment: Add Offset, Ramped Effects

Joints:

Joint_1

Connection Type: Body-Ground

Type: Cylindrical

Body: Wheel_1

Joint_2

Connection Type: Body-Ground

Type: Cylindrical

Body: Wheel_2

Change the direction of Z-axis as per above image.

Boundary Conditions:

After meshing as described above, create Boundary Conditions as given below:

Analysis Settings:

of Steps: 14
Auto Time Stepping: Program Controlled
Solver Type: Program Controlled
Large Deflection: ON
Nonlinear Controls:
- Stabilization: Constant
- Method: Energy
- Energy Dissipation Ratio: 0.1

Other Boundary conditions for joints are as given below:

Now we want to move the workpiece between two wheels up to 90 mm, so we have to give it a displacement.

Displacement:

Direction: -Y (Negative)

Joint Load_1:

Joint: Revolute – Ground to Wheel_1

Type: Rotation

Magnitude: Tabular Data

Joint Load_2:

Joint: Revolute – Ground to Wheel_2

Type: Rotation

Magnitude: Tabular Data

Solution:

After giving proper boundary conditions, create desired solutions for output results.
Create Solutions for :
- Equivalent Stress For Whole Setup
- Equivalent Plastic Strain for the Workpiece
- Directional Deformation in Z-axis for the Workpiece
- Directional Deformation in Y-axis for the Workpiece

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Results:

Now we will see the results for requested solutions.

Stress Contours (Whole Setup):

Stress Plot (Whole Setup):

Stress Data (Whole Setup):

Plastic Strain (Workpiece):

Plastic Strain Plot (Workpiece):

Plastic Strain Data (Workpiece):

Directional Deformation in Z-Axis (Workpiece):

Directional Deformation) in Z-Axis Plot (Workpiece):

As per above contour and plot, we can observe that initial width of workpiece was 9 mm and length or thickness 10 mm.
After deformation up to 6 mm each side, we get the width of workpiece up to 21 mm.

Directional Deformation) in Z-Axis Data (Workpiece):

Proof for Displacement of Workpiece up to 90mm:

Now we want to verify that workpiece has moved or displaced up to 90 mm in Y – Axis direction.
As we know, we have given Displacement to Workpiece up to 90 mm.
To verify it, we will see the Direction Deformation of the Workpiece and see that the Tip of the Workpiece has displaced up to 90mm or not.

Directional Deformation in Y-Axis (Workpiece):

Directional Deformation) in Y-Axis Plot (Workpiece):

Here in above contours image, we can see that Maximum displacement of the tip of the workpiece is 90 mm Maximum.
Also maximum deformation can be observed from the above plot.
This is the proof that Workpiece has displaced up to 90mm.

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Draught:

The difference between the thickness of initial and rolled metal piece is called Draught. Thus if t₀ initial thickness and t_f is final thickness, then the draught d is given by

d = t₀ - t_f

Here we can check thickness change by seeing the result of directional deformation in X-Axis.

So_,in this case,

T₀ = initial thickness / length = 10 mm

T_f = final thickness / length = 4 mm (decreased 3 mm each side)

d = 10 – 4

d = 6 mm

For Maximum Draught,

d _max= f² * R

R= Radius of Roller

F = Static friction coefficient

R = 25 mm

F = 0.2

So,

d _{max =}(0.2)² * 25 = 1 mm.

So we can get Minimum thickness or Maximum Draught from rolling Process = 1 mm.

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Conclusion:

This study of the rolling process drew every minute aspect. In terms of manufacturing engineering, every engineer should consider the rolling process as a core metal forming process. This process is mainly used when a cross-sectional area of a material required to be changed by an engineer.

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References:

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Animations:

Stress (Whole Setup):

Strain (Workpiece):

Directional Deformation in Z-Axis (Workpiece):

Directional Deformation in Y-Axis (Workpiece):

Directional Deformation in X-Axis (Workpiece):

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NOTE:

Due to large size of the Ansys file, i have attatched a link for the Ansys .wbpz file in below "Model Browse" area.

Kindly find attatched link via word document.

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Thanks & Regards,

Dharmesh Joshi

Week 4- Rolling operation

Ship work like this
in your own course.

Talk to a career counsellor

Ship work like thisin your own course.

Talk to a career counsellor

Ship work like this
in your own course.