Function integration method in technical problem solution development.
Belak, Stipe ; Belak, Branko ; Covo, Petar 等
Abstract: The paper deals with the complex system design as a
result of technical problem solution presented on the example of the
frictional planetary reducer of simplified structure design. The problem
solution is defined as technical complex system synthesis. The solution
is considered as a result of function integration process that starts on
the basis of initial design that consists of particular functional
claims that could be fulfilled using the single element or sub system of
higher grade. The system function integration process, aiming to the
technical system synthesis, is not executable without the inter
objectives definition. The solution synthesis is the most intriguing and
creative part of designing process. The Ideal Type Method application to
the function integration in the process of the system synthesis is
presented through the claim for wide standardization of the frictional
planetary reducer elements. The claims defines the use of standardized
connecting devices (screws, bolts, nuts, washers), bearings and bearing
assemblies, seal and sealing assemblies
Key words: function, integration, system, synthesis.
1. INTRODUCTION
The first aim of this paper is to present procedure of the function
integration on the planetary speed reducer example. To serve this
intention, the frictional type of planetary reducer is analyzed.
Technical problem is considered as a description of the expected
function of the technical system as a facility. Term technical problem,
in this paper, is certain description, list of claims or both of them to
one or more functional or other performances that should be fulfilled by
the problem solution. Problem solution starts by the function analysis
and ends by the system synthesis. The first part is the structured
analysis of the problem as entity, aiming to define the function
required by the problem definition and functional analysis of sub
problems of the first grade, definition and functional analysis of sub
problems of the second grade, sub problems of the third grade continuing
the analysis further to single function stage. The stage of the single
function defines the zero solution (initial solution) of the problem.
That enables the synthesis of the complex system initial design as the
problem solution. The solution synthesis procedure is, in principle,
very simple but in real design practice, particularly in complex system
design, it becomes very complex even in the first step of function
integration.
The Functional Optimization Method is presented in the paper
(Belak, 1991) on the basis of outline theoretical model of technical
problem analysis and technical system solution integration. The method
application on the scientific research is done in the reference (Belak,
1990), including working performance experimental measure, of the speed
reducer based on the ball bearing 6305 as integrated element. The
designer's practice is shown in references (Belak et al., 1993;
Belak et al., 1994; Belak, 1996). The Ideal Types, as an aid to the
function integration process (integration of two or more functions in
one system element), are used in the problem solution and in the system
development. Ideal types are, in the system solution synthesis process,
instructive connection to the system overall performances defined by the
problem definition.
2. ANALYSIS AND INITIAL SYNTHESIS
Technical problem, defined for the purpose of this paper is design
of the frictional planetary reducer of reduced and simplified structure.
The speed and torque reducing/multiplying function of the frictional or
other type planetary reducer/multiplier one can describe through the
following two basic functional claims or expected performances:
--function of torque transmitting (with torque reduction or
multiplication),
--function of speed reduction/multiplication;
2.1 System elements
The frictional planetary speed reducer/multiplier as technical
problem for the use in this paper one can define through the planetary
reducer classical structure consisting of the following elements (E):
E1--central "sunny" wheel; E2--planet wheels (runners);
E3--the planetary wheels carrier device; E4--casing wheel (in most
planetary reducers part of reducer housing); E5--planet wheels bearing
assembly; E6--central wheel shaft; E7--planet wheels carrier shaft;
E8--central wheel shaft bearing assembly; E9--planet wheels carrier
shaft bearing assembly; E10--housing.
2.2 System elements functions
The classical design of the frictional type planetary speed
reducer/multiplier performs its function as a synergistic assembly of
the system elements following functions: F1--function of torque and
speed transmitting and normal forces for frictional forces producing;
F2--function of torque and speed transmitting; F3--function of keeping
the planetary reducer internal geometry; F4--function of torque and
speed transmitting and normal forces (contact forces) for frictional
forces producing; F5--function of planet wheels controlled rotation
enabling; F6--function of planetary reducer input or output torque and
speed; F7--function of input or output torque and speed; F8--function of
central wheel shaft controlled rotation enabling; F9--function of planet
wheels carrier controlled rotation enabling; F10--function of the
planetary reducer integration.
2.3 Initial solution
After the problem functional analysis according the technical
problem analysis procedure (Belak, 1991), the single element function
scheme is reached as shown in the Table 1. Table 1 shows the initial
solution of the system i.e. frictional type planetary reducer. Ideal
types that are applied in this synthesis are based on the following
performances:
--system designed for both mass and one by one production;
--system based on standard mass produced elements or elements that
are widely used all over the world;
--at least 70% of the system internationally standardized elements
(ISO) has to be applied.
2.4 Ideal types
The ideal types based on noted claims could be defined, for
example, as follows: IT1 as an instructive and preclusive claim defines
production technology. It should be regularly assembly based. The claim
to most assembly technology and system elements world wide availability
implicates very high degree of integration based on standard elements
application as it is defined through the ideal types IT2, IT3 and IT4.
The percentage of standardized elements used in the system
synthesis should not be less than 70%; IT2 as a preclusive claim (100%)
defines that all connecting elements (bolts, nuts, washers) are produced
under the ISO standards claims and are to be of the standard first order
of applicability; IT3 as a preclusive claim (100%) defines that all
bearings and bearing assemblies are produced under the ISO standards
claims and are to be of the standard first order of applicability; IT4
as a preclusive claim (100%) defines that all seals and sealing
assemblies are produced under the ISO standards claims and are to be of
the standard first order of applicability.
The ideal types and their limitations to the solution synthesis as
noted leave full designer's freedom and possibility for
designer's creativity expression in the area of housing design and
applied bearing assembly selection. Although the housing design and
related bearing assembly selection are strongly defined and restricted
by the claim that the system could be produced even in the case of one
by one production.
3. THE SYSTEM SYNTHESIS
The system first synthesis is done on the elements that are
intended for the torque and speed reduction or multiplication. Using the
modified ball bearing (new element E11) as the basis of the frictional
planetary reducer one can integrate functions of elements E1 (central
"sunny" wheel), E2 (planet wheels), E3 (planetary wheels
carrier device), E4 (casing wheel) and E5 (planet wheels bearing
assembly).The new integrated function F11 realized in new integrated
element E11 is function of torque and speed transmitting and normal
forces for frictional forces producing and the planetary reducer
geometry control.
New integrated system solution is shown in the Table 2, where the
new element E11 integrates functions F1, F2, F3, F4 and F5. Applying the
presented system elements integration quite new structure of frictional
planetary reducer is developed. The main element E11 is ball bearing
modified in the way that ensures contact forces between the inner and
outer rings and the bearing balls. Contact forces between bearing balls
as planet wheels elements produce the frictional forces enabling the
function of the bearing elements as sunny wheel, planet wheels and
casing wheel as in typical design of frictional type planetary reducer.
The control of the reducer geometry overtakes the modified planet wheels
carrier that, in new design, takes place between bearing balls.
The basic function is input or output torque transmitting. To
reduce sliding friction between the bearing balls and planet carrier
bolts the rolling or sliding bearings are applied. In the first solution
synthesis the number of structural elements is decreased for 40%, and
all ideal types are satisfied. Considering that all bolts, screws, nuts,
washers, bearings, bearing assemblies, seals and seal assemblies easily
could be applied all claims are fulfilled. Further IT2, IT3 and IT4
ideal type claims could be satisfied in the elements E3 and E7 (Belak,
Covo, 1998).
4. CONCLUSION
The Functional Optimization Method is presented on the example of
the frictional type planetary speed reducer design synthesis. The basis
for the design solution is the claim to develop the planetary reducer of
significantly simplified structure and particularly the use of, at least
70%, internationally standardized and world wide available elements. In
the design synthesis process four ideal types are defined and applied.
The presented procedure is executable in many ways that mostly depend on
the designer's personality, acquired skills and experience. One can
consider presented methods pointless and the part of designer's
creativity
5. REFERENCES:
Belak S., (1990) Integral design of frictional planetary reducers,
(in Croatian) Ph. D. Thesis, FSB, University of Zagreb, Zagreb.
Belak, S., (1991) The Method of Analysis and Synthesis for the
Solution of the Technical Problem, Proc. of the XI SYM-OP-IS, Beograd.
Belak S., (1993)Design of the submachine guns family BM2K,
BM2L,(cal.9x19mm,cad.1100/1600r/min); Bagat PPM, Zadar.
Belak S., (1994)Design of the submachine guns family B5R (cal.
9x19mm, cad. 800/1400 r/min, system Robinson); Bagat Zadar.
Belak, S., (1996) The Synthesis of the Combined Bolt Design
Solution for Blowback Operated Automatic Weapons, Proc. of the 4th Intl.
Symposium Design '96, Opatija.
Belak, S., Covo, P., (1998) Design for Maintenance, Euromaintenance
'98, Proc. of the 14th European Maintenance Conference, Dubrovnik.
Table 1 System initial functional scheme (zero solution).
E1 [left and right arrow] F1
E2 [left and right arrow] F2
E3 [left and right arrow] F3
E4 [left and right arrow] F4
E5 [left and right arrow] F5
E6 [left and right arrow] F6
E7 [left and right arrow] F7
E8 [left and right arrow] F8
E9 [left and right arrow] F9
E10 [left and right arrow] F10
Table 2 System functional scheme after the first integration.
E11 [left and right arrow] F11
E6 [left and right arrow] F6
E7 [left and right arrow] F7
E8 [left and right arrow] F8
E9 [left and right arrow] F9
E10 [left and right arrow] F10
Table 3 The first function integration scheme (E11 synthesis).
E11
F1 [left and right arrow] E1
F2 [left and right arrow] E2
F3 [left and right arrow] E3
F4 [left and right arrow] E4
F5 [left and right arrow] E5