**3. Conclusion**

Designer must be significantly engaged into the forming of the component shape. Because of that reason, once formed algorithm for the modelling of the component shape is saved in computer memory and it is used when there is need for the modelling of the same or similar shape with similar dimensions. (Saric et al., 2009)

Parts which are not suitable for interactive modelling are modelled by parameters. In the process of geometric mechanical transmission modelling in CATIA V5 system, we do not have to create shape directly, but, instead of that, we can put parameters integrated in geometric and/or dimensional constraints. Changing of characteristic fixed parameters gives us a 3D solid model of mechanical transmission. This way, designer can generate more alternative designing samples, concentrating his attention on design functional aspects, without special focus on details of elements shape. (Saric et al., 2010)

For the purpose of final goal achieving and faster presentation of the product on the market, time spent for the development of the product is marked as the key factor for more profit gaining. Time spent for process of mechanical transmissions designing can be reduced even by 50% by parameter modelling use with focus on the preparatory phase (Fig. 12.).

Mechanical Transmissions Parameter Modelling 15

D mm appropriate diameter of belt pulley components

H mm appropriate length of belt pulley components

ha mm addendum part of cog height hf mm root part of cog height K - belt pulley KON - cone L mm helix length Lg mm hub length lc mm cone axis length m mm module N - number of helix P - plate PI - value of number

p mm step on pitch circle ROT - rotation r mm pitch radius ra mm addendum radius

rb mm basic radius

rf mm root radius

rr mm radius of profile root radius s mm minimal pulley rim thickness

ratio - factor of scaling exterior to interior cog profile

rc mm length of generating line of back (additional) cone

dg mm interior diameter of hub do mm diameter of the hole on the plate dop mm diameter on which holes on plate are set

dv mm diameter of shaft delta ° a half of an angle of front cone

G - hub gama ° angle of helix

d mm gear pitch circle; diameter of the hole for shaft; diameter of belt pulley

dZ mm translation of geometry over z axis; translation of worm surface over z axis

A mm side rib length a ° line of contact angle B mm side rib width Bk mm pulley rim width BR - side rib b mm cog width bg mm hub width bk mm keyway width bz mm gear width C mm side rib thickness CYL - cylinder

**5. Nomenclature** 

Fig. 12. Relation of design activities and reducing of time spent for design by parameter modelling

These are the advantages of parameter modelling use:


We can conclude that CATIA V5 system offers possibility of geometric association creation defined by relations established between parameters. Therefore, components parameterisation must obligatory apply in combination with today's traditional geometric modelling approach. Direct financial effects can be seen in production costs reduction, which increases the productivity. Therefore profit is bigger and price of products are lower. (Saric et al., 2010)

Obtained 3D model from CATIA V5 system is used as the base for technical documentation making, analysis of stress and deformation by *Finite Element Method* (FEM), generating of NC/CNC programs for production of the parts on machine (CAM/NC), *Rapid Prototyping* (RP), etc.
