Sensitivity analysis of several body-in-white single part and · Sensitivity analysis of several...

Sensitivity analysis of several body-in-white single part and

assembly parameters using tolerance analysis

Litwa, Frank1, Gottwald Martin1, Vicent Gascó1, Vielhaber Michael2

1 Daimler AG, Sindelfingen, Germany2 Institute of Engineering Design Saarland University, Germany

Weimar 04.-06.11.2015


assembly parameters using tolerance analysis - Agenda

• Overview

• State of the art

interrelationships and dependencies of product and process information

State of the art in tolerance analysis

• Concept to link an optimization tool

Abstract concept

Workflow in optiSLang

Concept for the Daimler internal Tool „TolSim & Optimizer“

• Validation of the concept using a simple example

• Conclusion and outlook

WOST; Frank Litwa; RD/KRR; Daimler AG 2



• Overview





Abstract concept





3 WOST; Frank Litwa; RD/KRR; Daimler AG


assembly parameters using tolerance analysis – Overview

Motivation:

• Increasing number of derivatives of one car

• More intense IT-usage required

• Need for cutting down the development time of new products

Description:

Manufacturability of product

backed by tolerance simulation

More complex products require an

experienced tolerance engineer

Scope:

The content of this presentation is an approach showing how to interlink optiSLang to product-/ and

production development data and to a CAT-simulation tool to perform sensitivity analysis on the

simulations input parameters.

4

Time consuming build-up process

of the tolerance simulation model

Optimization of different tolerance

concepts based on experts knowledge

Bildquellen: http://images.vogel.de/vogelonline/bdb/683400/683457/4.jpg, http://www.tcw.de/uploads/html/consulting/beratung/innovation/images/76_beschleunigung_1_gr.jpg,

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WOST; Frank Litwa; RD/KRR; Daimler AG



• Overview





Abstract concept







assembly parameters using tolerance analysis – State of the art

6

Tolerance simulation modell

Results of the

Tolerance simulationComparison

Design (Strak)

Gap- and radial plan

Section cuts

Measurements

Requirements

Measurement results

3D CAD data

Jig and fixture concept

Measuring points

Joining elements Datum target points

Tolerances (GD&T)

Assembly graph




Tolerance chain (definition):

„A linear dimension chain can be derived from dimensions on

parts which are pointing towards the same direction. The

closing dimension M0 closes the ends of the linear dimension

chain and is specified by a tolerance. This tolerance can be

derived out of the dimensional tolerances of the single parts.“

(Klein 2007)

Dimensional technical specifications (definition):

A dimensional technical specification is a

dimension which is relevant for a specific

function in the BiW structure (e.g. connection of

the chassis). To ensure manufacturability these

dimensions are limited by certain tolerances.

7

Quelle: F. Litwa




Gap- and Radial Plan:

In the Gap- and Radial Plan a detailed specification is made

describing the dimension of gaps, flushness and radiuses and also

the allowed deviation (tolerance) for predefined section cuts of the

fully assembled vehicle.

The gap- and radial plan is an agreement between the departments

of design, product development and production. In an early stage of

the product development process this document serves as a

default for the product development and later on for the production

process.


2 ± 0,5

R 0,5 ± 0,1

RY-577RX-427 RX-370

Initial situation:

• Deviations of the single parts due to the manufacturing process of

the parts

• Maximum allowed deviation of the parts is limited by the usage of

tolerances

• Deviations of the parts alignment in the jig due to inaccuracies of

positioning of the parts

• Assembling process of the deviating single parts to a higher level

assembly leads to a deviation in the closing dimensions

Tolerance simulation:

For evaluating the range of the deviations during series production

tolerance simulation is used.

9



Simulation offers two different types:

Tolerance analysis: single part tolerance is known result is the deviation of M0

Tolerance synthesis: maximum allowed deviation of M0 is known results is the

single parts tolerances

10

B

asi

c p

rin

cip

lefo

rto

lera

nce

sim

ula

tion Initial Situation ZB

Nominal gap in the assembly of an the

angle profile and a cuboid

ZBn

Assembling & Measurement

Implementetion of the predefined

assembling operation followed by a

statistical measurement of the gap

Division & SamplingDivision of the single parts (n-

times) followed by a random

sampling.

n x Simulation runs

RemoveingAll the components are

only used once Trash

Angle profile an cuboid cn

n x angle profile n x cuboid






• Overview





Abstract concept






12

Design

Datum target points

Gap- and radial plan

Section cuts

Measurements

Requirements

Measurement results

3D CAD data

Jig- and fixture concept

Joining elements

Tolerances (GD&T) Measuring points

Assembly graph

Target value

Loop

Input parameters

• diskrete or

continous

parameter

• permitted

range is kown

• continous

parameter

Optimization



assembly parameters using tolerance analysis – Concept

Tolerance simulation modell

Results of the

Tolerance simulationComparison


Sensitivity Analysis of Several Body-In-White Single Parts and

Assembly Parameters Using Tolerance Analysis – Concept

Tool for Variation Analysis

Initialization

• Definition of the working directory• Selection of the *.dcsx-file

• Selection of input parameters• Selection of output responses• Setting of sampling method• Determination of number of samples• Definition of constraints

Project Settings

Visualization of the Results

Results of TolSim

• Deviation type• Standard deviation• …

Results of Sensitivity Analysis

• Contributors• Meta-Modell• …

Perform TolSim + Results

3DCS (batch call)

*.csv-File

optiSLang (batch call)

*osl3.bin

Database

• Part (Points [FTA, SFK, VE, MP], Tolerances)

• Assembly Graph

*.dcsx-file

Database (Output) (reduced)

Algorithm

• Creation of 3DCS Model

Results of TolSim

Creation and Execution

of Sensitivity Analysis

Product and Process Information

Tool for automated CAT-simulation





Initialization



Project Settings


Results of TolSim





3DCS (batch call)

*.csv-File


*osl3.bin


Database


• Assembly Graph

*.dcsx-file


Algorithm


Results of TolSim






• Overview





Abstract concept






Y

XZ

+

-

Flushness measurement

Gap measurement

Nominal measurement

In Y-direction

Inaccuracy of the fixture

22

2D-representation for the used example:



assembly parameters using tolerance analysis - Validation

X4

X5

Y

XZ

- Alignment of the two gray parts in the assembly station

(3-2-1 alignment)

- Only one tolerance in the assembly station (profile of a

surface ±0,5) describing the inaccuracy of the

assembling process

- Alignment of the blue part at the gray parts as shown

- Only one tolerance at the blue part describing the

inaccuracy of the stamping process of the single part

- Three measurements for the resulting gap between the

blue part and the dark gray part

- Z-alignments of the blue part can be changed in an area

of ±4𝑚𝑚

1,0D ZXY

1,0D ZXY

Z3Z1

Z2

Y6

23

Results of a sensitivity analysis (CoP-Matrix):




Y

XZ

+

-

Z3Z1

Z2

Input Parameters

Targ

et

va

lue

s

𝜌(X,Y)=𝐸[(𝑋 − 𝜇𝑋)(𝑌 − 𝜇𝑌)]

𝜎𝑋𝜎𝑌

24

Results of a sensitivity analysis:




- Main contributor for the flushness measurement

is the X-direction of the datum target point Z3

Y

XZ

+

-

Z3Z1

Z2

25







- Main contributor for the gap measurement is the

X-direction of the datum target points Z1 and Z2

Y

XZZ1

Z2

Z3

26







- Main contributor for the gap measurement is the

X-direction of the datum target points Z1 and Z2

- Main contrubutor for the Y-measurement is the X-

direction of the datum target points Z1 and Z2 Y

XZZ3Z1

Z2



• Overview





Abstract concept







• Sensitivity analysis of several body-in-white single parts opens up several possibilities:

- Main contributions of tolerances in a tolerance chain (similar to HLM analysis in the tolerance simulation)

- Statement of how the layout of assembling points (datum target points, jig- and fixture points, welding points)

are infecting one (ore more) quality feature(s)

• More rapid feedback to the designing engineers

• Study of options available in a very short amount of time

• Comparison of different alignment concepts, etc. possible

• Optimization with regards to Robust Design possible


assembly parameters using tolerance analysis – Summary

Frank Litwa (Daimler AG)

Development Body in White

Dimensional Management (RD/KRR)

Phone: + 49 7031 9078210

mailto: [email protected]

Conclusion & Outlook:

Contact:

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