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