TJWA WOW1 Web Handling · PDF fileNipped%Roller% Systems 4:$Nipping$&$Laminaon$ ... $Process,$Roll$Quality,$EquipmentDesign$ ... Nip$Design$ Nip$Variaons$

Webs Tension Rollers Nips Lateral Wind More

1.0 What is Web Handling Introduc7on and Overview

Timothy J. Walker, TJWalker + Associates Inc. 1620 Edgcumbe Road, Saint Paul, MN 55116

[email protected] www.webhandling.com 651.686.5400

TJWA Inc., Copyright 2012 www.webhandling.com 1


What is Web Handling?

Ø  The process technology of transporOng and storing thin, flexible materials.

Ø  A web is any flexible, conOnuous material where:

Length >> Width >> Thickness

Ø Webs include papers, films, foils, non-‐wovens, texOles, and laminates.

Thickness Width Length



Web Handling Processes

Makers: Coa7ng, Extrusion, & Paper and Film-‐Making

Converters: SliOng, Die-‐CuOng, & Lamina7ng

Controls! Cri7cal to successful web

handling.



Web Handing Technology Areas

1: Introduc7on to Webs and Web Handling

2: Tensioning

3: Rollers and Trac7on

4: Nipping and Lamina7on

5: Lateral Control

6: Winding

7: WH Resources

TJWA Inc., Copyright 2011 www.webhandling.com 0-‐4

Web ProperOes of Tensioning


WH Fundamentals

Web ProperOes of Tensioning

The Secret to Web Handling

1: Introduc7on to Webs and Web Handling


+  Web Proper7es ü What material proper7es does a web handler need to know? ü Know your web’s mechanical and fric7onal proper7es.


Tension Control Systems

Tensioning Elements

MD Tension Profile

2: Tensioning

WH Fundamentals


+  Tension Control ü What is the right tension for your web or process? ü What controls tension in your process? ü What determines the op7mum number of tension zones?


3: Rollers & Trac7on

WH Fundamentals

TJWA Inc., Copyright 2011 www.webhandling.com

Roller Basics Alignment TracOon

+  Rollers and Trac7on ü Design rollers for driving, idling, and nipping applica7ons ü Why is roller parallelism important? ü Understand when webs slip on rollers.


WH Fundamentals

TJWA Inc., Copyright 2011 www.webhandling.com

Nipped Roller Systems

4: Nipping & Lamina7on

LaminaOon

+  Nipping and Lamina7on ü What is the load and pressure in a nip? ü What causes or reduced pressure varia7ons? ü What are the best prac7ces of lamina7on?


WH Fundamentals

Guiding Wrinkling Spreading

5: Lateral Mo7on: Tracking, Wrinkling, Spreading, Guiding


Tracking

+  Lateral Mo7on ü What cause a web to shib laterally? ü What web guide is best for a process? ü What causes web wrinkles? ü What eliminates wrinkles?


WH Fundamentals

6: Winding: Process, Roll Quality, Equipment Design


Winder Design

Roll Quality

Winding Process

+  Winding, Rolls, Winders ü What winder design is best for a product? ü What determines the pressure inside a wound roll? ü What causes roll and web defects?


WH Fundamentals

7: Web Handling Resources


+  Resources ü Where can I learn more about web handling? ü Where can I get help with web handling?


Web Handling and Winding Common Problem Areas


Tension VariaOons

Web Buckling

1.  Tensioning 2.  Imperfect Webs 3.  Nipping Roller Systems 4.  MD and TD Control 5.  Web Buckling

Imperfect Webs

MD and TD Control

Nipped Roller Systems


Part 1: Solu7ons w/ Web Tensioning

Machine Direc7on

Tension: MD VariaOons

Tension: Too High or Too Low

Tension: TD VariaOons

Transverse Direc7on TD =

MD =

Tension: Varies Over

Time Tension:

Slit Strands

1A 1B 1E

1D

1C



Part 2: Solu7ons with Imperfect Webs

Baggy Webs

Cambered Webs

Cambered and Baggy Webs

Curled Webs

Non-‐Flat Webs


Part 3: Solu7ons to Nipping Varia7ons

Nipped System Design LaminaOon

Nip Varia7ons Nip Design


Part 4: Solu7ons with Control

MD Slip on Rollers

MD Slip Between Web and Driven or

Idler Rollers MD Slip in Rolls

MD Slip Between Layers in a Rolls

TD Slip/Shi` on Rollers

TD Error in Rolls

Web TD Shibs or Slips Laterally on

Rollers

TD Shib or Misalignment of Layers in a Rolls

Machine Direc7on Control

Transverse Direc7on Control


Part 5: Solu7ons with Buckled Webs

In Spans

Buckled Between Rollers

Buckled Web in Spans

MD Buckles On Rollers

TD Buckles On Rollers

On Rollers


In Rolls

MD Buckles Rolls

TD Buckles in Rolls


Ques7ons }  What do you want to learn? }  What ques7ons do you have? }  What materials are you working with? }  What processes are you working with? }  What are your top sources of waste related to web handling? }  What would you like to share from your experience?



1.1 -‐ Web Proper7es What makes one web different from another?



TJWalker + Associates Inc. www.webhandling.com 18



Web Proper7es WHAT IS IT What webs are difficult?

•  Extremes of thickness Ultra-‐thin (less than 0.5 mil or 12 microns) Ultra-‐thick (unable to bend around a roller)

•  Extremes of width Ultra-‐narrow (less than 0.2-‐in or 5mm) Ultra-‐wide (over 100-‐in or 2.5m)

•  Extremes of elasOcity Ultra-‐s7ff (steel) Ultra-‐stretchy (polyurethane, some nonwovens, elas7cs) Visco-‐elas7c and non-‐elas7c

•  Easily damaged Easy to tear, break, crush, deform, scratch

•  Difficult surface properOes Slippery, tacky, fric7onal proper7es varying as a func7on of pressure



Web Proper7es WHAT IS IT What processes are difficult?

•  Fast (above 1000 fpm) •  Ultra-‐precise (registra7ons below 3-‐5 mils, 75-‐125 microns) •  Process with drama7c mechanical property changes (paper-‐making, film-‐

making/orienta7on, extrusion coa7ng on films) •  Long air flota7on ovens •  Webs in vacuum •  Webs in liquids •  Speed or length transi7ons (accelera7on, accumula7on/dispensing, turret

winders) •  Ultra-‐long processes (over 300m web path) •  Extreme tension transi7ons, esp. to and from zero tension •  Lamina7ng greatly dissimilar mechanical proper7es curl free, esp.

anisotropic to isotropic webs •  Machine direc7on registra7on



WH Technology HARDWARE/SOFTWARE What analogies or images are helpful? Webs are like springs:

•  Most webs respond elas7cally to force or need force to elongate Webs are like ropes:

•  Webs bend easily (except widthwise) •  Webs don’t support compression (easily buckling) •  Webs work well under tension (they are s7ffer and straighter)

Webs are like beams: •  They have a cross-‐sec7on area •  Think of load in term of stress (force/area) •  Bending force is func7on of bh3/12, un7l buckling •  Bending force is func7on of 1/L3, un7l buckling


What is Your Web? Webatronium?


}  Thickness, Width }  Stress or Strain to Yield or Break }  Young’s Modulus of Elas7city }  Surface Characteris7cs (Fric7on, Roughness, Porosity) }  Visco-‐Elas7city? }  Poisson’s Ra7o? }  Anisotropy? (MD-‐TD Differences) }  Layers? Laminate? Coated?


What is the right tension?

The Right Tension Qs

The answer to this requires understanding of:

force, tension, stress, strain,

tensile-‐elonga7on tes7ng, yield point, break point,

& modulus of elas7city.



Web Handling Stress

εσΔ

Δ=E

ducOle break σ

stress

strain, ε

(force/area)

x x brifle break

yield point

elasOc strain

(%)

Typical web handling tensions are 10 to 20% of a web’s yield or break stress.

Tension setpoint should be 10-‐20% of yield or break point.



Common Units & Variables

TJWalker + Associates Inc., Copyright 2011

www.webhandling.com SWHP1-‐25

t = web thickness, mils or inches, 0.001” = 25µm w = web width, inches, 1” = 25.4mm L = length, inches, 1” = 25.4mm V = web or roller speed, feet/min. (fpm), 100 fpm = 30 m/min D = diameter r = radius FT = Force of tension, lbs, 1 lbs = 0.454 kg T = tension force per width, pli, 1 pli = 175 N/m

(pli = Pounds / Lineal Inch of width) σ = web stress, psi, 1 psi = 6.9 kPa ε = web strain, dimensionless E = Young’s modulus, psi, 100,000 psi = 690 MPa θ = wrap angle, degrees or radians


Tension Units (SI)

FT Tension Force

Force lbs (kgf or N)

T Tension

Force per Width pli (kgf/m)

FT = 10 kgf FT ~ 100 N

FT = 10 kgf w = 0.5 m T = 20 kgf/m T ~ 200 N/m

FT

FT w, width wFT T=



Tension Units (English)

FT Tension Force

Force lbs

T Tension

Force per Width pli

FT = 10 lbs FT = 10 lbs w = 10 in. T = 1 lbs/in T = 1 pli

FT

FT w, width

FT

FT



What tension will break or deform a web?


What is stress? What is strain?

What is modulus? TJWA Inc., Copyright 2012 www.webhandling.com 28


Tension Units (SI)

twF

=σ

FT Tension Force

Force lbs (kgf or N)

T Tension

Force per Width pli (kgf/m)

σT Tensile Stress Force per Area lbs/in2 (kPa)

FT = 10 kgf FT ~ 100 N

FT = 10 kgf w = 0.5 m T = 20 kgf/m T ~ 200 N/m

FT = 100 N w = 1 m t = 25 µm σT = 4 MPa

w

t, thickness FT

FT w, width wFT T=



Tension Units (English)

FT Tension Force

Force lbs

T Tension

Force per Width pli

σT Tensile Stress Force per Area

lbs/in2

FT = 10 lbs FT = 10 lbs w = 10 in. T = 1 lbs/in T = 1 pli

FT = 10 lbs w = 10 in t = 0.001 in σT = 1000 psi

w

t, thickness FT

FT w, width



KEY CONCEPT

Stress Stress and pressure are both defined in units of force per areas. To berer understand any web process, convert forces into stresses by dividing the load by the cross-‐sec7onal area it is exerted over.

Use: Machine tension is commonly measured as a force in units of lbf, kgf, or N. To compare different products or processes, calculate tensile stress by dividing tension force by product thickness and width.

Example: FT = 50 lbf creates higher stress as cross-‐sec7onal area decreases. For w=50” and t=0.010”, the tensile stress is a low 100 psi. For w=50” and t=0.001”, the stress is 1000 psi. For w=1” and t=0.001”, the stress is 50,000 psi!

!



Strain Defined

00

01

LL

LLL Δ

=−

=ε

L0 = Dimension of zero tension web

L0

L1

L1 = Dimension of tensioned web

ΔL

Strain, ε, is the ra7o of the change in a dimension over the untensioned dimension. For tensioning, strain is the change in length over the untensioned length.



KEY CONCEPT

Strain Strain is dimensional change in a solid material in reac7on to stress. For posi7ve stresses, materials will elongate in the direc7on of the stress. For nega7ve stress or pressure, materials will compress. Strain is calculated as the change in dimension divided by the original dimension.

Use: When a web is forced to conform around varia7ons in roller parallelism or diameter, the web’s response will begin by determining the web strain. Example: If a roller diameter varies from 5.00” to 5.05”, the web develop a 1% strain differen7al to conform to roller.

!



Tensile-‐Elonga7on Tes7ng

Tension or

Force

%ElongaOon

Most tensile-‐elonga7on tes7ng focuses on measuring ul7mate break strength or elonga7on, but should provide other mechanical proper7es.


Images courtesy of Instron


Tensile Elonga7on Tes7ng Yielding (2) is a permanent, non-‐elas7c dimensional change.

Each material has a characteris7c stress and strain where yield begins – called the yield point.

N TJWA Inc., Copyright 2012 www.webhandling.com 35

Break with brifle fracture

Break with ducOle fracture

Web handling systems are designed to avoid reaching a material’s

yield point.


Break Point

The break point is the ul7mate, catastrophic end to high elonga7ons or high stresses.

Brirle materials have lirle yielding prior to breakage. Duc7le materials will have significant yielding prior to the break point.

σstress

strain, ε

Force Area

Break with brifle fracture

(%)

Break with ducOle fracture

X

X



The ‘magic’ tension is 1 lb/in or 1 PLI.

Typical Tensions

80-‐90% of processes run between 0.3 and 3.0 PLI

95-‐98% of processes run between 0.1 and 10.0 PLI

175 N/m or 18 kgf/m

50 N/m or 500 N/m

17 N/m or 1750 N/m TJWA Inc., Copyright 2012 www.webhandling.com 37


Web Handling Stress

εσΔ

Δ=E

ducOle break σ

stress

strain, ε

(force/area)

x x brifle break

yield point

elasOc strain

(%)

Typical web handling tensions are 10 to 20% of a web’s yield or break stress.

Tension setpoint should be 10-‐20% of yield or break point.



Why is a 5:1 or 10:1 tension safety factor needed?

Tension, Strain,… Qs

Tensioning systems control average tension.

Web and equipment imperfec7ons can create larger MD and TD

varia7ons from average tension.



Visualizing Tension Varia7ons

+30 -‐20

+20 -‐5

+20

72

A thermostat will indicate the temperature at one point, but the temperature will vary from point-‐to-‐point within the house.

40lbs 1PLI

80lbs 2PLI 70lbs

0PLI

1.5PLI 0.2PLI

1.8PLI

A load cell or dancer roller will control or indicate the tension at one point in a process, but the tension will vary through the process, both MD and TD.



Sources of MD and TD Tension Varia7ons

Baggy Web

T

width

T

width

Misalignment Drag and Iner7a

T

MD

T

width

Diameter Varia7ons



From data given in the next few slides, what would be the right tension for PET, PP?

How about at elevated temperatures?




Some Proper7es of PET

From DuPont Teijin Films Mylar® Data Sheet



Yield Stress and Temperature Stress

-‐-‐-‐-‐-‐-‐-‐-‐-‐

Stress -‐-‐-‐-‐-‐-‐-‐-‐-‐

From DuPont Teijin Films Mylar® Data Sheet



Measuring Modulus

twF

=σStress, p

si

Strain,%

F

L

dL

Calculate modulus by noOng the length change of a strip under a

known weight (tension).

LLδ

ε =

( )twLFLEδδε

δσ==



Modulus is Important

It is quite common to find quality labs measuring break or yield points, but

never calcula7ng modulus.

Knowing modulus is quite useful in web handling and

cri7cal to lamina7ng.



Modulus? We Don’t Do Modulus!

Force, lbs

Strain,%

Quality labs commonly have tensile elonga7on testers for break, peal , or tear tes7ng, but when asked to measure

modulus, 1) have never done it, 2) don’t know how to, and 3) find no help in the equipment manual...

= very frustrated web handler.

Output Data

Unshared Data!



Modulus Defined

DucOle Break σStress

Strain, ε

(psi)

x x

Ε=Δσ/Δε

Brifle Break Yield Point

ElasOc strain

(%)

Modulus is the ini7al slope the stress-‐strain curve. It describes a web’s “stretch-‐ability.”

σ

ε

High modulus: Foils

Papers Polyester

BOPP HDPE

PE, Vinyl, PU

Low modulus:




Using Elas7c Modulus

The elas7c modulus is a material property that describes the rela7onship of stress to strain.

εσΔ

Δ=E

σstress

strain, ε

(force/area)

(%)

Eεσ =

Eσ

ε =

ε = 0.01 = 1% E = 500,000 psi σ = εE = (0.01)(500000) = 5000 psi = 5PLI / mil

σ = 0.5 PLI / 0.5 mil = 1000psi E = 200,000 psi ε = σ/E = (1000)/(200000) = 0.005 = 0.5%



Tension/Strain Ra7o

For webs with difficult to define thickness, tension to strain ra7o can be a useful replacement for modulus.

εΔΔ

=TK '

Tension

strain, ε

(force/width)

(%)

'KT ε=

'KT

=ε

ε = 0.01 = 1% K’ = 50 PLI T = εK’= (0.01)(50) = 0.5 PLI

T = 2 PLI K’ = 40 PLI ε = T/K’ = (2)/(40) = 0.05 = 5%

T


Fric7on Coefficient

The fricOon coefficient, m, is the raOo of fricOonal force relaOve to normal load. Two common fricOon coefficient measurement methods are:

Sliding Block Test

WF

=µ

FricOon

Applied Force W

LRISE

LRUN

RUN

RISE

LL

=µ

Incline Plane Slide Test

Copyright 2014, TJWA Inc. www.webhandling.com 51


The Belt Equa7on

µθeFF

LO

HI =

For simple rollers, the belt equa7on is a useful equa7on, describing the fric7on that develops between a web and roller.

FHI = High Tension, lbs FLO = Low Tension, lbs µ = Web-roller coefficient

of friction θ = Wrap angle, radians

Web slides over non-‐rota7ng cylinder

θ

FHI

FLO Force to Begin Slip and Lib

θ

FLO

Force to Begin Slip and Drop

FHI



Measure Fric7on (Web-‐Roller)

µθeFF

LO

HI =

θ

TLO THI

W

( )θ

µ LOHI FFln=

Use the belt equaOon to determine web to roller fricOon. 1.  Take a strip of web and tape loops on each end.

Arach a mass to one end and weight it with the force gauge.

2.  Wrap the target roller with a known wrap angle.

3.  If necessary, hold the roller so it doesn’t rotate. 4.  Pull with the force gauge un7l the web slides on

the roller, note the force, F (Tension ra7o is F/W).

5.  For a second data point, push with the force gauge, dropping the tension un7l the web slips the other direc7on. Note the force, F (Tension ra7o is W/F).

6.  Enter the tension ra7o and wrap angle (in radian) in the belt equa7on and calculate fric7on coefficient.

F



What is the Poisson's ra7o?




Strain = Dimensional Change

FT = 0 FT > 0

For solid materials, tensile and compressive stresses do not significantly change density.

Increases in length (MD strain) is offset by decreases in the width and thickness.

Tensioning Increases Length

Thickness & Width

Decrease



TD Contrac7on

⎟⎠

⎞⎜⎝

⎛−=−=twEFX

XY ννεε

)(0 XT ww νεδ −= FX

Tension, thickness, width, modulus (stretchiness) and Poisson’s raOo determine how much the web will contract.

No Tension

Tensioned

width

N TJWA Inc., Copyright 2012 www.webhandling.com 56


What is elas7city? What is visco-‐elas7city?




KEY CONCEPT

ElasOc vs. ViscoelasOc Behavior Elas7c materials respond to stress with an immediate strain change and recover to ini7al dimensions when stress is removed. Viscoelas7c materials will have a 7me-‐dependent response to stress or strain.

Use: Most webs can be considered elas7c. Example: Tensioning a web will create an immediate stretch (a.k.a. strain), that is independent of 7me or speed.

!

Use: Under constant load, a viscoelas7c webs will con7nue to stretch over 7me. Example: Hang a weight on a strip of vinyl electrical tape and measure the length over 7me.



Elas7c Behavior

σ

ε

7me

7me

Elas7c Response

Response

Input

Elas7city ElasOc materials will respond proporOonally and immediately (at the speed of sound).

Applied stress will result in web strain.

Applied strain will result in web stress.



Viscoelas7c Behavior -‐ Creep

σ

ε

7me

7me

Elas7c Response

Viscoelas7c Response

Response

Input

Creep Test

A constant stress is applied to the web.

Response is strain.



VE Behavior – Stress Relaxa7on

ε

σ

7me

7me

Elas7c Response

Viscoelas7c Response

Response

Input

Stress Relaxa7on A constant strain is applied to the web.

Response is stress.












1.2 Bagginess and Curl What is…? What causes…?





How thick is a web?

}  The answer to this is oben a easy, but not always.

•  Easy: Foil, most films, coated papers •  Confusing: Papers? Thickness can be measured, but are more oben described by ‘weight’ (i.e. mass per area).

•  Difficult: Non-‐wovens, tex7les, porous films (anything easily compressed).


Thickness, Thickness Profile


What is a web’s thickness profile?

}  Thickness mapped vs. width.

}  Does the web have thick edges? Lanes?

}  Is the thickness profile consistent over 7me?

}  Does the product have inten7onal thickness profile (including coa7ngs or cutouts)?

}  How is thickness profile measured? (Besides in winding defects)


Thickness, Thickness Profile


}  Manual physical measurement Increase accuracy by measure a stack mul7ple sheets 10 layers, then divide by number in stack.

}  Automated Off-‐Line }  Beta radia7on transmission }  Capacitance }  Physical contact (LVDT) }  Mass per area weight sampling


Measuring Thickness

Capacitance

Absolute Contact

Combined

www.oaklandinstrument.com


}  Automated On-‐Line }  Radia7on (beta, x-‐ray) transmission }  Radia7on (gamma) backscarer }  Near infrared (transmission, reflec7on) }  Capacitance }  Laser micrometer }  Laser curtain on roller


Measuring Thickness

Scanning

www.ndc.com

Same Spot Differen7al



Thickness Profile Measurement Op7ons

www.sbi.at



Closed-‐Loop Thickness Profile Control

Thickness profile measurement is oben

combined with sobware and controls to make automa7c adjustments of

extrusion or coa7ng dies.

www.sbi.at


Solu7ons to Imperfect Webs

TJWalker+ Associates Inc., Copyright 2011


Baggy Webs

Cambered Webs

Cambered and Baggy Webs

Curled Webs

Non-‐Flat Webs

Bagginess and camber are oben strongly related to

winding.

Curl is strongly related to coa7ng and lamina7ng

(and some7mes winding).


What is web bagginess? What is web camber? What is web curl?

Imperfect Web Solu7ons Ques7ons



How are they measured?


Definition: A web with crossweb length variations. A web is considered baggy if the strain of tension does not pull the web to flatness.

Measuring Bagginess: •  There are many methods to qualify or

quantify bagginess. •  Most are difficult, expensive, or time-

consuming. •  A manual pull out and 1-to-5 grading

may be the simplest. •  For films, roll hardness can be a

useful predictor or bagginess.

2A: Baggy Web




2B: Skew/Camber



Definition: Skew (a.k.a. Camber) is the most common term for a non-straight web. A cambered web will bend left or right when rolled out under no tension. (Slit strands cut from baggy web may be skewed.)

Skew

Measuring Skew: Skew is typically measured by pulling, rolling, or sweeping out a long sample on a tabletop or floor and quantifies the left or right bias of the web relative to straightness.

Long and Loose Edge

Short and Tight Edge


Definition: Curl is the tendency for a web to not lay flat (especially coated or laminated webs), instead form into a curved or scroll shape.

Measuring Curl: Curl is best measured in narrow strip samples. Strips samples are usually cut in the machine or transverse (crossweb) direction, but may be cut at any angle.

2C: Web Curl




Tensioning Baggy Webs



T0 = 0

T1 > 0

T0 = 0

T1 > 0 T2 > T1

The ideal web carries tension uniformly across the web width.

For an imperfect web, tension stretches the short lanes first. When short lanes are stretched to equal the long lanes, the web appears taut.


Cambered Web (a.k.a. Skewed Web)



A cambered or skewed web has one side longer than the other.

A cambered web will curve left or right when rolled or swept out on the floor.

Straight Web

Cambered Web

Long Side

Short Side

Long Side

Short Side

Cambered Web Cut into Strips

All Lanes Equal

Straight Web Cut into Strips


SliOng Baggy or Cambered Web



If a slit roll is cut from a baggy web across a lane in the transition

from short to long lanes, the slit roll will be cambered.

Short Lane

Long Lane

Short Lane

Short Edge Long Edges

Short Edge


What causes TD length varia7ons in paper, film, or foil manufacturing ?

Imperfect Web Solu7ons



A short, but not complete list why paper, film, and foil making has TD length variations includes: Machine misalignment Crossweb moisture variations Uneven calendaring Variation in roller diameters Uneven web paths or nip loads in blown film collapsing Cooling or stress variations in tenter quenching zone Nip variations in laminating or film extrusion nips



More on Curl… More on Bagginess…

More on curl in Sec7on 4 Nipped Rollers and Lamina7ng

More on bagginess in Sec7on 6 Winding and Roll Quality


Tension Control 1.  How do you determine the target web handling tension for a

given product in units of force or force per width? 2.  What are three causes of tension varia7ons across the web’s

width (i.e., things that create a loose edge or center). 3.  What advantage does a dancer roller have over a tension load cell

roller in a closed-‐loop tension control system. 4.  What advantage does a tension load cell roller have over a dancer

roller in a closed-‐loop tension control system. 5.  What are advantages and disadvantages of draw control (a.k.a.

speed ra7o control).

Web Handler’s Quiz



Rollers, TracOon, Nipping/LaminaOng 6.  What is a reasonable specifica7on for roller alignment in mm/m,

milli-‐radians, or mils/in.? 7.  Which rollers in a process are like to have above average

diameter? Why? 8.  When is a nipped roller needed on a driven roller separa7ng two

tension zones? 9.  What is a simple measurement to determine if two nip rollers are

pressing together uniformly? 10.  If a two-‐layer laminate product curls to the top layer in the

machine direc7on, which would reduce the curl: increase or decrease the top layer pre-‐laminate tension?




Tracking, Wrinkling 11. For automa7c guiding in the middle of a process, which is

preferred: a steering-‐type guide or a displacement-‐type guide? 12.  In a ver7cal span, which will cause the web to track off center

more, a roller tram (misalignment vs. machine center line) or level error (misalignment rela7ve to gravity)?

13. Name four mechanisms that will cause the web to track off centerline through a series of rollers.

14.  If you see wrinkles at low speeds, but the wrinkles go away at higher speeds, what is the most likely reason?




Wrinkling, Spreading 15.  If a roller is deflec7ng into a bowed shape due to gravity, which

direc7on is it best NOT to approach that roller if you don’t want to wrinkle: ver7cally from above, ver7cally from below, or horizontally?

16.  What spreader or an7-‐wrinkle rollers do NOT have a rubber surface?




Winding, Unwinding 17.  If you center wind at constant torque, what is the percent change

in tension if the roll diameter changes from 100 mm to 400 mm? 18.  If you wind a paper and a film product of equal thickness and roll

geometry at the same combina7on of winding condi7ons (tension, nip, taper, speed), which is likely to have higher internal roll pressures?

19.  Name three advantages of using a nipped or gap-‐controlled roller ahead of winding?

20.  What is an easy way to determine if an unwinding roll is cinching (i.e., some of the roll’s layers are slipping in the machine direc7on?





Apply Torque to Rollers and Rolls

Driven Rollers/Rolls Clutched Rollers/Rolls

Braked Rollers/Rolls


Open-‐Loop Torque Motor


Unwinding Op7ons

Open-‐Loop Brake

Brake with Diameter Feedback

Brake with Load Cell Feedback

Brake with Dancer Feedback

Motor with Diameter Feedback

Motor with Load Cell Feedback

Motor with Dancer Feedback



Unwinding Op7ons

Surface Roller Driven Unwind



Surface Belt Driven Unwind

VV

V

V

Surface driven unwinds are typically speed ra7o controlled, but could be closed-‐loop tension control with load

cell or dancer feedback.

Surface roller /belt




Unwinding Peel Roller Op7ons

Driven Unwind with Idling Peel Roller

Braked Unwind with Idling Peel Roller

Peel rollers are lightly loaded against the unwinding roll and may be driven to reduce the tension increase due to peel force.

Braked Unwind with Driven Peel Roller

Driven Unwind with Driven Peel Roller

Peel roller are used to reduce web path varia7ons from peel force

varia7ons (for unlinered adhesive coated webs or other products with side A to B bonding forces).



Web Support / Transport / Tensioning Op7ons

Rectangular Bar / Plate

Curved Bar / Plate

De-‐Curl Bar / Roller

Roller




+P

Air Greased Bar / Plate

Roller Curved Bar / Plate

+P

Air Float Bar / Plate




Vacuum Roller

Nipped Roller

Unnipped Roller

-‐P

µθeTT

LO

HI = NT µ=Δ ( )TwrPfT ,,,,, θµ=Δ


Roller Op7ons – Live vs. Dead Shab, Idler vs. Driven


Live Sha` Idler Roller Dead Sha` Idler Roller

Bearings

Live Sha` Driven Roller

Shab rotates with shell. Shab does

not rotate.



Winding Op7ons: Center Driven

Center+Surface Driven Winder

Center Driven Winder

Surface Driven Winder


Open-‐Loop Torque Motor


Winding Op7ons: Center Driven

Open-‐Loop Clutch

Clutch with Diameter Feedback

Clutch with Load Cell Feedback

Clutch with Dancer Feedback

Motor with Diameter Feedback

Motor with Load Cell Feedback

Motor with Dancer Feedback



Winding Op7ons: Surface Driven

Surface Roller Driven Winder

VV

Surface Belt Driven Winder

V

V







Winding Op7ons: Center-‐Surface Driven

Surface Belt Driven Winder

V

V





Surface Roller Driven Winder

VV


Roller Op7ons

Live Sha` Idler

Dead Sha` Idler

Dual Bearings

Direct Driven Roller

Torque Driven Roller

Tendency Driven Roller

Idler Roller Op7ons Driven Roller Op7ons



Can7levered Roller Op7ons

Dual-‐Wall CanOlevered Sha`

CanOlevered Support

CanOlevered Sha`








Web Proper7es WHAT IS IT Descrip7on What are the sub-‐technologies?

Intro Level Learning? •  Thickness, Width •  Young’s Modulus of Elas7city •  Surface (Fric7on, Roughness,

Porosity) •  Breaking, Yielding •  Poisson’s Ra7o •  Layers? Laminate? Coated?

Advanced Level Learning? •  Visco-‐elas7city? •  Anisotropy? (MD-‐TD Differences) •  Thickness measurement and profiles •  Bagginess and Curl •  Memory •  Thermal Expansion •  Hygroscopic Expansion •  Variable geometry: discon7nui7es

(holes, patches), profiled cross-‐sec7on, widgets



Web Proper7es WHAT IS IT Where is it used?

Paper, Film, Foil, Packaging, Medical/Pharmaceu7cal, Electronics, Construc7on, Magne7c, Imaging, Op7cal, Barery, Solar, Food, Carpet/Tex7le



WH Technology PROFIT (or LOSS) = BENEFITS -‐ COSTS What is profit (or loss) of doing it well? •  Con7nuous processing webs is more efficient (higher yields, higher

produc7vity) than sheet or part processing. •  Using thin webs reduces material costs. •  Using marginal quality (baggy) webs to make product reduces

waste, lowers costs.

Documents

TJWA WOW1 Web Handling · PDF fileNipped%Roller% Systems 4:$Nipping$&$Laminaon$ ... $Process,$Roll$Quality,$EquipmentDesign$ ... Nip$Design$ Nip$Variaons$