2005 virtual product development conference | 24 – 26 ... · pdf filesipa , is a world...

2005 Virtual Product Development Conference | 24 – 26 October, 2005 | Munich, Germany

D.R.R.D. Cam Design and Optimization

Marco Testa, Technical Department, Designer Engineer

S.I.P.A. S.p.A. - ZOPPAS INDUSTRIES


IRCAHeating Systems

IRCA (I)

ZIR (Romania)

ELTERM (Brazil)

ZIH (China)

ZIM�STILL-MAN (Mexico)

RICA (I)

RICA FRANCE (F)

ELTRA (D)

HILZINGER (D)

SEV (I)

SIPA NORTH AMERICASIPA SUL AMERICASIPA ARGENTINASIPA ROMANIASIPET TURKEYSIPA CHINASIPA JAPAN

SIPA THAILANDSIPA RUSSIA

SIPAPlastic Packaging

Systems

SIPA, is one of the companies of ZOPPAS INDUSTRIES which is a solid industrial group operating in the following business segments:• Plastic packaging systems• Heating systems

SIPA, is a world leader in design and construction of systems for the production of plastic containersfor soft drinks, mineral water, food and non-foodapplications.

• Founded in 1980• Employees: 770• Turnover 2004: 186 Millions €• Machines sold at June 2005: 1296 units• Countries where SIPA machines are installed: 88• Technical Service Centers in 20 Countries

The Group, with over 6,000 employees, has 10manufacturing facilities located in 9 countries.IRCA, is number one in Europe in the production of electrical heating elements and systems for large and small household appliances, environment heating systems and industrial applications.

ZOPPAS

INDUSTRIES

SIPA North AmericaAtlanta - USA

SIPSAMexico City - Mexico

SIPA Sul AmericaSao Paulo - Brasil

SIPA ArgentinaBuenos Aires - Argentina

SIPA Moscow - RussiaSIPA Kiev - Ukraine

Madrid -Spain

SIPA JapanTokyo - Japan

Frankfurt -Germany

SIPA ThailandBangkok - Thailand

SIPA Middle EastDubai - U.A.E.

SIPA - Italy

SIPETIstanbul - Turkey SIPA China - Beijing

SIPA China - Hangzhou

SIPA RomaniaTimisoara - Romania

Warsaw -Poland

Manila -Philippines

Dhaka -Bangladesh

Teheran -Iran

The Company


ECS: 1-Step Systems from 2,000 to 30,000 bph

PPS: Preform Injection Systems from 2,000 to 28,800 pph

SF: Linear Blowing Systems from 1,000 to 9,000 bphSFR: Rotary Blowing Systems from 12,000 to 48,000 bph

Molds & Hot RunnersPET Injection and Blowing

Turn-key lines

SYNCHRO: Integrated Blow-Fill-Cap System

SIPA’s Product Offer


SFR Systems ViewFocus on a press of Rotary Stretch Blowing System at ω = 150 deg/s ⇒ 1500 bph/cavity


Aim of the Virtual PrototypeThe increase of performance of our machines and the design speed are the aim of this study.

• a process to design a cam on a machine which produces PET bottles from preforms

• the non-conventional process is based on the MSC.ADAMSapplication and we will able to design and test an optimized cam profile and moreover to generate the output path for its final machining

• this aim can be achived up through virtual simulations, in which we can directly use the parts designed by cad 3D in a virtual model: the multybody analysis is the only way to obtain a realistic simulation of mechanism in which cam movements and impact are combined.


• Definition of the model through rigid bodies from 3D CAD to MSC.ADAMS™

The virtual prototype



• Kineto-dynamic analysis to verify the mechanical process




• Kineto-dynamic analysis to verify the mechanical process

• Design and optimization• To reach the target

• Driving the mechanical system

• To improve performance• Simultaneously to the new cam design



• Blowing Press

Yesterday…were made...Blowing Press

• 1 d.o.f. mechanism• 4 rods, 6 joints• rotating mould

Cam follower

Rods


Yesterday…were made...

• D.R.R.D. cam opening/closing moulds• Symmetrical Dwell-Rise-Return-Dwell• Graphical design using an advanced CAD• Kineto-dynamic analytical evaluations


• To reduce times of development ⇒ virtual instead of physical prototyping

• To reduce usury ⇒ costs • To have higher performance if possible

The way to improve dynamic behaviour of the mechanism have to be different from the graphic approach which involves too many loops between the design and the analysis ⇒ cam design have to be automated.

Why OPTIMIZATION wanted?

CADCAD

CADCAD

CalculusCalculusCalculusCalculus

DDwellwell

RRiseise

RReturneturn

DDwellwell

}It is clear that the best cam profile produces minimal efforts both in the cam and inthe joints of the blowing press.


The history teaches...Analysis show that cam classical motion laws aren’t fitting for the mechanism. From the kinetic point of view of rollers, it’s rather difficult to reproduce the acceleration law using several combinations of polynomial curves, trigonometric base curves or their modifications, paying attention to:• maximum acceleration value• trend of acceleration law (which is the best)• 1st, 2nd and 3rd derivative of displacement (velocity, acceleration, jerk must be also continuous)


The history teaches...Looking at the reaction force on the original cam, is possible to see that at the maximum force corresponds more or less zero acceleration.This shows that the cam is mechanism dependent; it’s also important to go along with inertia forces because of structural limit conditions: actually a 40 kg mould system is opening and closing in less than 0.6 seconds when the productivity is 1750 bph/cavity. The overlap of several blowing stations must be considered for total machine vibrations.


• TARGET: THE FORCE ON THE CAM• Symmetrical (let’s consider half cam)• Regular and always acting to keep contact• Mechanism dependent

• Inertia forces• Mould opening

• Inserting preforms (not very difficult)• Extracting bottles (rather difficult, mould must be

opened as many as possible)

The way to...As the target is to reproduce and minimize the reaction on the cam, why don’t use thethe FORCEFORCE instead of a motion law? In this way CAM CAM REACTION FORCEREACTION FORCE can be directly customized by user, looking at the constraints of the system and driving it to the OBJECTIVEOBJECTIVE desidered.


The way to...The original FORCEFORCE have to be reproduced in half cam ⇒ a suitable number of analytical functions must be found.

As working with a FORCEFORCE means working on acceleration, the body-moving FORCEFORCE have to be continuous. In order to have jerk continuous, analytical functions must be well rounded.Dynamic effects must be also considered to write the logic function of the FORCEFORCE, depending both on the type of mechanism and the movement(initial conditions, joint reactions, mechanical process).


The way to...Moving the cam follower with a FORCEFORCE, the model has 1 d.o.f. Let’s try with a total parametrized modified trapezoid function made by 6 laws:

( )

( )( )( )( )( )( )

=

tf

tf

tf

tf

tf

tf

tF

6

5

4

3

2

1

6

65

5

4

42

2

αωt if

αωtα if

αωtinv if

invωtα if

αωtα if

αωt if

>≤<≤<

≤<≤<

≤

2α 4α

5α 6αinv

( )tf1 ( )tf2( )tf3

( )tf4

( )tf5 ( )tf6

iablesdesign var

changeable 01⇒

Input FORCEFORCE first must be directed outside to open mould, then inside to stop inertia force in the right way, leaving the mould enough opened to do transfert operations.


• Objective function• Stroke needed SSdd

• Velocity function when stroke is SSdd

Pre-optimization...To realize kineto-dynamic boundary conditions, MSC.ADAMS DESIGN EVALUATION TOOLS is used:

• Design Of Experiments• Variables-matching• Trials that satisfy both motion

and dynamic conditions

( ) ( )( )velocityγ,strokeγΓΓ 21objobj =


• Goal is minimize ΓΓΓΓobj :

• Constraints• Maximum joint force

Optimization...

( ) ( )( ) 0velocityγ,strokeγΓ 21obj =

…as an index from the prevoius analysis

jointjoint FF ≤


• The DesignOptimization...


- OPTIMIZED- NOT OPTIMIZED


Results...• Dynamic point of view

• Maximum cam force value is less 10 %

• Constraint joint force is respected



Results...• Kinematic point of view

• Maximum acceleration value is less and the trend is the same

• Process point of view• Mould opening is bigger



• The design itself: automated process

Advantages...

CADCAD

CADCAD

CalculusCalculusCalculusCalculus

• After optimization rise cam is mirrored in the return one ⇒⇒⇒⇒ D.R.R.D. CAM


• The “non conventional” method• Using a FORCE instead of a MOTION LAW

• Cam action can be directly driven and dynamic of the blowing press is get for free

• Performance increasing• Machines speed could be enhanced

• Virtually tested and validated getting off expensive tests• The optimized cam are now in production!

Advantages...


Thank you…!


• Paper Reference No. : EMEA05-086

D.R.R.D. Cam Design and Optimization

Eng. Marco TestaS.I.P.A. S.p.A. - ZOPPAS INDUSTRIESTechnical Department/Designer Engineer [email protected]

Dr. Piero Pace, MSC.Software Italy

Further Contacts

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