Development of a drilling machine for an asymmetric element with
multiple holes
STROE Sergiu1,a, ONESCU Constantin2,b* and INAL Cagri3,c
1,3
Aka Automotiv, 364 A, Calinesti, Argeș Country, Romania
2
University of Pitești, Targu din Vale street, no.1, Pitești, Romania
a
b
c
sstroe@akaoto.com.tr, constantin.onescu@upit.ro, cinal@akaoto.com.tr
Keywords: asymmetric element, drilling machine, multispindle head, flat extruded engine, FAST
method
The aim of this paper is to develop a drilling machine for 5 holes simultaneously
manufactured for an asymmetric element from automotive industry. The function analysis system
technique (FAST) and SADT (Structured Analysis and Design Technique) is used to identify,
describe and categorize the drilling machine functions in order to propose technical solution. The
paper propose an original solution with flat extruded engine for the closest 2 holes to avoid the
usage of multispindle head.
Abstract.
Introduction
The study of systems using the functional analysis started in 80’s years and it was developed several
methods to identify and develop the functions and technical solutions [1].
The functional analysis steps and its tools are given in [3, 6] and is shown in fig. 1 as general
recommendation for technical systems development.
External Functional Analysis
Requirement Functional Analysis
Requirements
Octopus
Diagram
Internal Functional Analysis
Product Functional Analysis
Functional
specifications
Product general
definition
Product
elements
definition
Functional table
FAST
SADT
Main function
Constraint function
Charts, Technical
solutions
Plans, schemas
Fig.1 External and Internal Functional Analysis Scheme.
The analysis of multispindle drilling machines shows that the most of technical application use the
multispindle head [3] or gang drilling machine [2] to solve simultaneously execution of multiple
holes. The drilling arrangements discussed above are suitable for symmetric elements where the
manufacturing cost is reduced.
To find the technical solutions to service functions usually two methods are found in literature
review: FAST - Function Analysis System Technique and SADT - Structured Analysis and
Design Technique [1]. In the paper, FAST method is used to choose the technical solution and
SADT to establish the input and output data and schemas for the chosen solution.
In the paper, the basic arrangement for asymmetric element drilling machine is a mobile table with
the 5 drills assembled on it, in one of the several configurations which will be proposed.
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External Drilling Machine Functional Analysis for Asymmetric Element
The asymmetric element is from automotive with the shape and dimensions given in figure 2. It is a
bended tube with square section. The holes have to be cutting are to the superior area and are
denoted from C1 to C5, the value of diameter is 6.7 mm and 1.5 mm as depth.
Fig.2 Holes positioning for the asymmetric element for car.
The external environmnent are idenfied and the main and constraint functions are found building
the octopus diagram (figure 3).
MF1 : Worker to be able to drill 5
holes in the same time to the
assymetric element
MF2 : to be integrated in the
production flow
CF1 : to fix the assymetric element
CF2 : to conect to the electrical
network
CF3 : to respect the worker security
CF4 : to be ergonomically for worker
CF5 : to resist/adapt to environmnet
Fig.3 Octopus diagram for multiholes drilling machine.
After the system functions identification the next step is to found the functions performance level
(and flexibility range) attended by the company.
The functional specification is prepared to express the company requirements. The drilling machine
has to:
-
Drill simoultanesously the holes 1 to 5 with the dimensions from figure 2
-
Drilling cycle (up and down) – 12 to 15 seconds
-
Assymetric element fixation force 200 N
-
Work area height – 1..1.2 m
-
Actuation and Security warning.
Applied Mechanics and Materials Vol.
Study of proposed technical solutions using FAST
The FAST (The function analysis system technique) is used to obtain the technical solution for the
multiholes drilling machine. The main (service) function 1 (to drill 5 holes in the same time to the
assymetric element) is decomposed into technical functions to find the technical solutions.
Service
(main)
function 1
To drill 5
holes in
the same
time to the
assymetric
element
WHY ?
HOW ?
Technical functions
Technical
solutions
Element
positioning
Produce
positioning
surface
Horizontal
support
Element
fixation
Produce
fixation force
Manual
fixation
Pneumatic
Fixation
On/off
buttons
Electrical
energy supply
5 holes drill
cutting
Produce
Thrust Force
Table 1
Technical
solutions
Fig.4 FAST diagram for multiholes drilling machine.
The condition of simultaneity is solved using a mobile table to supporting electric motors. Another
solution could be the possibility of axial movement separately for each drill (gang drilling machine)
but the problems are the synchronism of all 5 drills to assure the same feed rate, the size and the
price of the system.
To solve the first main function several technical solution are proposed in Table 1:
1- The first solution uses a single electric motor
coupled with a multispindle head [5]. Because
the holes are asymmetrically positioned and the
distances between them are considerable
(between 100 mm and 500mm) this system is
complex and expensive to use.
Single electric motor + multispindle drill head.
2- The second solution uses a mobile table and
three electric motors of size 71 on it (calculated
from input drilling parameters) used for the holes
situated at bigger distances. For the closest holes
(102 mm) a single motor a mechanical
transmission (belt or gears) is used.
To maintain the rotation sense is better to use a
belt transmission with poly V configuration, but
the disadvantage is pre-tensioning and limited
durability. Also, other disadvantages of this
solution are supplementary modification in order
to positioning drill peak in the same plane and the
maintenance activity is restricted.
Mobile table with 3 single-drill motors
and 1 motor – transmission- 2 drills.
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3-The third solution uses of one motor for each
drill. From input drilling parameter (feed rate 1.5
mm, cutting speed 60m/mm) calculus it obtains:
Feed Force 518 N and motor power 0,55kW [4,6].
The size of chosen motor is 71 that means a 140
mm body diameters, there are no possibility to
position 2 motors for the holes with 102 mm
distance.
To maintain the solution of one motor for each
drill even for the holes distance of 102.67 mm, it
finds the flat extruded motor shows below.
Mobile table with 5 single-drill electric motors
Mobile table with 5 single-drill electric motors
(3 cylindrical and 2 flat body)
Table 2 Main function - Technical solution assessment
System proposition
Multispindle head
3 motors-drill + 1
motors –Mech.
transmission (belt)
3 motors-drill + 1
motors –Mech.
transmission (gear)
3 motors-drill+2 flat
motors-drill
Technical
Efficiency
Standardization
Reliability
Price
TOTAL
2
5
2
4
1
14
5
3
4
3
2
17
5
3
4
3
2
17
4
4
5
5
2
19
Within the table 2 taking into account several criteria (with scale between 1..5) is given technical
solutions assessment and the last technical proposition is chosen for technical simplicity and price.
Implemented technical solution
The flat extruded body is found in [7] with the value of 98.5 mm as width which means that the
available distance of 102.67 allow the mounting of two Type50 flat motors nest to each other
(fig.5).
The drill drive choice was a first step for building the multi-holes drilling machine used for the
asymmetric element. From FAST analysis, the next steps are designing of the mobile table drivetrain, the element fixation during the holes cutting, the stand design (with the linear guides), control
and security devices.
The total price of drilling machine which contains mechanical, electrical and pneumatic systems is
reduced with 40 percent comparative with the price required by a drilling machine supplier
consulted by the company. The high standardization degree of the adopted drilling machine means
the maintaining of the company suppliers.
Applied Mechanics and Materials Vol.
Fig.5 Flat extruded body electrical motor implementation for C2-C3 holes [6].
a.
b.
Fig.6 Implemented technical solution. a) CAD Modeling; b) Real system.
Structured Analysis and Design Technique
The functional representation of multiholes drilling machine is implemented, also, in SADT model
(Structured Analysis and Design Technical ). For a global view, the first level is denoted A-0 where
is taking into account the different technical data [8].
Fig. 7 SADT A-0 for multiholes drilling machine.
Input data: element on which acts => asymmetric elements for drilling.
Main (global) function: operation on the input data => drill 5 holes in the same time into the
asymmetric element.
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Support activities: support technique, system which allows to achieve the global function=>
automatic drilling.
Output data: what is obtained after transformation (output data = input data + added value)
=> drilled elements .
Constraints and control data: in order to achieve the functions;
- W : energy to assure the functions => electrical energy (5 Drilling motors – total 2.75kW and 1.5
kW for the mobile table movement) and pneumatic energy for fixation
- C : system configuration linked to the production flow => automation, cycle choice (automated or
manual)
- E : system exploitation => start/stop command, emergency stop.
- R : system settings => time (15 seconds per cycle), speed, feed rate (0.15mm/rev).
Conclusion
To development of the multi-holes drilling machine for an asymmetric element, apparently, is an
easy job. The paper uses external and internal functional analysis to solve this issue. The solutions
from table 2 are functional but taking into account several criteria for assessment it retains for
implementation the solution with mobile table and 5 motors (3 classic motors and 2 flat extruded
motors). After machine drilling building, within production flow it works very well, the proposed
solution being reliable and economically suitable. Also, the paper shows a good co-operation
between industry and academia to solve industrial issues.
References
[1] L. Zehtaban, D. Roller, Systematic functional analysis methods for design retrieval and
documentation, World Academy of Science, Engineering and Technology Vol:6 (2012) 10151020.
[2] E. Widiyono, R. Wardhani, and L. Rusdiyana, Engineering Design of A Gang Drilling Machine
Equipped with Jig and Fixtures to Make A Prototype Machine in Birdcage Production. IPTEK, The
Journal for Technology and Science, Vol. 22, No. 4 (2011), 214-220.
Reference to a book:
[3] P. Severin, Biotechnology, Health, Environment, Functional Analysis, Toulouse 2009.
[4] A. Vlase, Manufacturing Engineering, Technical Publishing House. Bucharest, 1996
[5] ***Multispindle head, Romai Robert Maier Gmbh, 2013.
Reference to a website:
[6]http://www.kennametal.com/en/resources/calculators/holemaking-calculators/torque-thrust
power.html
[7] http://www.rossi-group.com/index.php/products/electric-motors
[8] http://www2.cslaval.qc.ca/cdp/UserFiles/File/telechargement/analyse_systemique.pdf