Chapter the following industrial applications: · Assembly· Machine

Chapter 1 Introduction

Industrial automation
has evolved to a stage where numerous other technologies have emerged from it
and have achieved a status of their own. Robotic automation is one such
technology which has been recognized as a specialized field of automation where
the automated machines have some human like properties 1. The Robotic Industries Association (RIA) defines an industrial
robotic manipulator as follows: “An industrial
robot is a reprogrammable, multifunctional manipulator designed to move
materials, parts, tools, or specialized devices through variable programmed
motions for the performance of a variety of tasks” 2.Industrial robots
are employed to automate a wide range of processes which are generally too
dull, dangerous or dirty for human operators. Moreover, advance robotic
manipulators have enabled us to achieve new levels of precision, accuracy,
repeatability and productivity which are of prime importance in many modern
engineering applications. Robotic automation is mostly used in the following
industrial applications: ·      
Assembly·      
Machine Tending·      
Welding·      
Material Removal·      
Material Handling·      
Palletization and De-Palletization·      
Vision InspectionIt can be inferred,
from the above definition, that a robotic manipulator enables precise motion
along a pre-defined trajectory. But a complete robotic automation solution
involves much more than just achieving desired movements. Each application has
its own special need, leading to a complicated design, simulation and
configuration process, which makes robotic integration very cumbersome and time
consuming. Selecting the right
robotic arm, peripheral equipment and end-effectors has critical importance for
a robotic application.
Material handling in a press line, for example, requires highly customized
end-of-arm tooling with suitable end-effectors, with or without special
functions, to perform the desired task. These components vary
with the process, material type, material properties like temperature and surface
finish, the automation function and many other factors. Additional requirements like automatic tool changing and more degrees of freedom, required for
higher production flexibility, make
the integration process even more complex.
The emergence of new robotic applications every year coupled with increasing
demand for customized robotic solutions has significantly increased the variety
of components required to maintain a certain level of customization. Therefore,
it becomes very important to develop standardized methodologies for
designing, configuring and integrating robots in order to keep product complexity under control. The following
section describes the research motivation
and objectives of this thesis project.1.1 Research MotivationThe advent of
Industry 4.0 has greatly affected the manufacturing industry. The full impact
of the fourth industrial revolution on the manufacturing world is yet to be
discovered. But it can be considered as a futuristic model of growth and
development which would lead to the creation of “smart factories”. These
factories of the future would be characterized by a high level of wireless
connectivity and data sharing between machines through the power of IoT.
Another salient feature of these factories would be modular physical structures
which could be replicated in the virtual world to control and monitor processes
to make decentralized decisions. In order to achieve this, a high degree of
standardization of manufacturing equipment and processes is needed.Robotic automation
has been identified as one of the key technology drivers of the fourth
industrial revolution. This means that industrial
robots will play a major role in realizing the factories of the future. But as introduced earlier, the process of
integrating robotic equipment in a production process is slow and complicated
due to the highly specialized and customized nature
of its configuration. This also leads to variety induced complexity and causes
difficulty in managing automation projects effectively. Hence, there is
a need to develop innovative solutions to standardize the robot configuration
and EOAT design process without compromising on flexibility and customization. 1.2 Aim and ObjectivesWithin the scope of
this thesis, titled as “Definition and creation of robotic automation
modelling- and configuration-kit for composite forming functions”, the primary
objective is to create standard pre-configured construction modules for easy
definition and design of robotic automation functions used in the composite
forming industry. The secondary objective is to develop a configuration tool
for easy configuration and project cost calculation. This modelling and
configuration-kit aims to reduce the variety of different components and
functions required to configure a robotic automation function in an automated
production line for a more effective project process and reduced design and
startup work. It also aims to balance the
opposing forces of standardization and customization to minimize complexity
costs in a company. The tasks defined
to achieve these objectives are as follows:·      
Assimilation of compression molding processes
and robotic automation functions used in a Dieffenbacher composite production
line.·      
Definition of standard EOAT sizes and masses for
robotic loading, unloading, stacking and de-stacking functions.·      
Definition of standard robot categories based on
load calculations for about 70% of all robotic applications at Dieffenbacher.·      
Creation of robot peripheral construction
modules.·      
Definition of a standard EOAT structure and
creation of standard EOAT construction groups and modules.·      
Design and definition of interfaces between
standard modules.·      
Finding ideas and specifications for developing
a configuration tool.·      
Development of the configurator application.·      
Testing the configurator with past projects as
test cases.1.3 Thesis OutlineWith the aim,
objectives and tasks laid out for the thesis project, chapter 2 starts with a
brief introduction to the company Dieffenbacher, which then leads to a
discussion about processes and technologies used in the Composites division.
This helps in establishing the role of robotic automation in an automated press
line. The robotic functions required in each compression molding process along
with composite material properties are highlighted in this chapter.                        

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Chapter 2 Technology and Process Overview

This chapter starts
with a brief introduction to the company Dieffenbacher. Following is a
discussion about relevant processes, technologies and functions from Business
Unit Composites to understand the role of robotic automation in a fully
automated press line.2.1 The Company DieffenbacherDieffenbacher is an internationally active group of
companies with over 1700 associates and 16 production sites and sales offices
worldwide. The company specializes in the mechanical engineering and plant
construction sector and is one of the leading manufacturers of press systems
and complete production systems for the wood, automobile, and supplier
industries. As an independent fifth generation family owned company, they have
stood for continuity, tradition and reliability for over 140 years. About 70%
of all products are exported internationally and the worldwide service and
sales network guarantees every customer the fastest possible support.The company can be divided into three main business units:1.    
Wood-based panels2.    

Composites3.    
Recycling Figure
1
Business Unit Composites of Dieffenbacher The wood division is the largest business unit which offers
complete production lines for the production of particleboard MDF, OSB and LVL
panels as well as fiber insulation panels and molded door leaves. The customers
of this business area are predominantly found in the woodworking, furniture,
construction and energy industries.The composites division is involved in processes, presses
and fully automated production lines developed and realized for the production
of light weight fiber reinforced plastic components. Most of the customers are
from the automotive and supplier industry.The recycling division focuses on development of complete
recycling plants for treatment of different waste materials through mechanical
and biological means for the extraction of secondary raw materials or energy.2.2 Press TechnologyThe composites division specializes in the
development of press systems available in standard and high-accuracy variants
with or without active servo-controlled parallel motion systems. The presses
are designed by keeping in mind the requirements of the plastic and composite
forming industry. Depending on customer requirements, Dieffenbacher is able to
supply suitable press systems with process-oriented controls.

Figure
2 Dieffenbacher Press Types There are currently three different press
types:1.    
Dieffenbacher Compress Lite (DCL)The DCL press type is available in an
upstroke and short-stroke design with a low overall height and an energy-saving
drive. The bevel deflection line provides an even bend progression of the upper
and lower die. The high-precision parallel motion behavior ensures a consistent
component thickness and increases the quality of the components. The Lite
concept provides exceptional flexibility and rapidness in die changing due to
its 4-sided accessibility.2.    
Compress Eco (DCE)   3.    
Compress Plus (DCP)      2.3
Compression Molding ProcessThis project focuses on finding standard solutions for
robotic handling of advance composites in a compression molding line. Material
characteristics like temperature, surface quality and stiffness determine the
type of end-effector suitable for its handling. These properties depend on the
material handling function and the type of compression molding process.
Therefore, it is very important to analyze these processes and their production
lines in order to understand different robotic functions. This understanding is
later used to define the right end-effector for each robotic function.Compression molding is a composite forming process in which
the preheated molding material is positioned in the cavity of a molding tool
and formed by application of external pressure and temperature. Pressure is an
important process parameter and is generally controlled by a mechanical press.
The ability to produce lightweight parts with high strength and complex
geometries makes this process suitable for a wide range of industries. Another
reason contributing to the popularity of compression molding is the possibility
of using advance composites. Advance composites include fiber reinforced
composites (FRC) which contain dispersed fibers in a continuous matrix phase. Carbon
and glass fibers are the most widely used reinforcements.Depending on the material hardening principle, compression
molding can be classified into the following types:1.    
Thermoset 2.    

Thermoplastic Figure 3 Compression Molding Processes  2.3.1 Thermoset In compression molding of thermosetting compounds, the hardening
process involves a chemical reaction called curing. Curing is irreversible in
nature due to cross linking of polymer chains. This chemical bond formation
requires application of heat. Once solidified, further heating does not lead to
melting but causes thermal decomposition of the compound. Hence, they cannot be
reshaped. They require low internal mold pressures of 40-100 bar and pressure
build up time of about 1 second. Due to curing, the forming process is
relatively slower with lower press velocities and longer cycle times (60-180
seconds).Dieffenbacher provides complete production lines for the
following thermoset forming processes:1.    
SMCSMC stands for sheet molding compound which is a compression
molding process as well as a fiber reinforced composite. The compound is
composed of carbon or glass fiber reinforcements which are dispersed in an epoxy
resin matrix. It is tacky, plastic and flexible in nature and supplied as
continuous sheets. Figure 4 shows the layout of a typical Dieffenbacher SMC
Duroline..

Figure 4 Fully Automated SMC lineThe SMC Duroline is a near unmanned complete production line
including milling, drilling and water-jet cutting stations (11) for finishing the
formed SMC components. SMC sheets are unwounded at the unwinding station (1)
and reduced to desired shapes and sizes at the cutting station (2). The feeding
robot (5) transfers the cut sheets from the conveyor (3) onto a stacking table
(4). The stacking table monitors the weight of the stack to control the volume
of SMC material being loaded into the press. The feeding robot then transfers
the SMC stack into the mold cavity (8) of the high precision press (7). The
unloading robot (9) transfers the finished components onto a cooling station
(14). The mold cleaning robot (10) enables automatic press mold cleaning after
a fixed number of cycles.SMC is suitable for manufacturing automotive components
which require excellent surface qualities like bumpers, air deflectors,
fenders, front panels etc.2.    
D-SMC The SMC Directline process provides higher process stability
and higher material quality by elimination of semi-finished processes. In
D-SMC, the semi-finished product is directly manufactured in the production
line before processing. This provides higher flexibility in recipe formulation
and helps in reducing storage and transportation costs. Further processing of
this material is similar to a conventional SMC production line. Figure 5 shows
a schematic

representation of a Dieffenbacher SMC-Directline.Figure 5 Dieffenbacher SMC DirectlineThe robotic automation functions and material properties
encountered at different stages of the production process in a SMC-Directline
are comparable to the conventional SMC process.3.    
HP-RTMHigh pressure resin transfer molding is a resin injection
compression molding process which uses a carbon fiber reinforced plastic (CFRP)
preform as a semi-finished product. The complete HP-RTM process, including
preforming, resin injection, curing and post processing, can be integrated into
one production line. The complete production line can be divided into three main
automated units:·      
Preform Center·      
Press and Injection Unit·      

Figure 6 Example of CFRP 3D preform

Machining UnitThe preform center allows production of custom designed
preforms from dry carbon fiber reinforced plastic. A stacking robot is used to
position reduced CFRP sheets on a conveyor belt for draping where they are heated
and accurately positioned on a stamping dye. The stamping process converts 2D
sheets into dimensionally stable 3D preforms. The preformed sheets are then
shaped using a cutting robot and stacked in a load trolley. Other robotic
functions in a HP-RTM line include de-stacking preforms, loading preforms and
unloading finished components from the mold.

Figure 7 HP-RTM Process Chain 4.    
Wet Molding

Figure 8 Wet Molded Components

Wet molding, which is an economical alternative to HP-RTM, is suitable for
components with two and a half dimensional characteristics. As semi-complex
geometries can be achieved without preforming, wet molding uses CFRP stacks instead
of preforms. This eliminates the need for preforming and reduces the cycle
time. Moreover, resin application is done outside the press. This allows
simultaneous resin application while components are still curing inside the
press which further shortens the cycle time. Figure 8 shows exemplary wet
molded components.

Figure 9 Dieffenbacher Wet Molding LineFigure 9 depicts a fully automated wet molding line. A handling
robot de-stacks the CFRP stacks from the carrier garage and positions them on a
scanning table where they are perfectly aligned for proper resin application. Stacks
are then transferred to a cabinet for robotic resin application. The amount of
resin applied is strictly monitored to maintain uniformity and enhance repeatability.
The feeding robot loads the wet stacks into the wet molding press. After curing,
a de-stacking robot unloads the finished parts and moves them into a cooling
press. Finally, the cooled components are transferred to the conveyor belt for
manual inspection.  2.3.2 Thermoplastic

Thermoplastic compounds solidify on cooling and become
moldable on application of heat. They are characterized by strong
intermolecular forces which weaken on heating and therefore they can be
reshaped. Compression molding of thermoplastics require high internal mold
pressures of 150-250 bar and pressure build up time of less than 0.5 seconds.
Due to absence of a chemical reaction, the forming process is relatively faster
with higher press velocities and shorter cycle times (20-50 seconds).

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