FOR DISMANTLIING AND ASSEMBLING HARD-TO-SEPARATE MECHANICAL ASSEMBLIES ON MECHANICAL PLANTS

The paper presents a new technical solution, a device for dismantling and assembling parts of mechanical plant components which are not easily separable. The device design allows wide possibilities of application in maintenance and repair of hydro power plants, thermal power plants, and diesel electric generators, in motor industry, shipbuilding industry and navy, aircraft industry, and turbines in process industry. The device for dismantling and assembling is universal and easy to use. Its small weight makes it easy to transport to locations with machine facilities.


Introduction
During the years of maintenance and overhaul of mechanical plants, there has been a need to invent and design a device for assembling and dismantling hard-to-separate mechanical assemblies on mechanical plants.The device was supposed to have a wide range of applications: hydro power plants, thermal power plants, turbine systems in process industry, ships, reciprocating compressors, gas turbines, internal combustion engines, machine tools and other plants.This means that potential users are companies engaged in the production and maintenance of systems in: hydropower plants, motor industry, shipbuilding industry and the navy, aviation industry, turbine plants in process industry, manufacturers of gears, sliding and rolling bearings and other machine elements.The main part of the work shows the structure and the possibilities of the device application (Tehnička dokumentacija za Mini hidroelektrane Elektroprivrede Crne Gore,1964).
Description of the construction of the device for mounting and dismantling hard-to-separate mechanical assemblies Figure 1 shows a device for mounting and dismantling hard-toseparate mechanical assemblies (Žegarac, 2004).Position (1) in Fig. 1 is a hard-to-separate mechanical part that is to be removed for replacement of other parts.Positions (2-5) are the parts of the device for removal.Position (2) indicates the anchor bolts, position (3) denotes the hydraulic device, positions (4) and ( 5) are pressure plates with different diameters, and position (6) represents the screws for joining pressure plates.Holes for anchor bolts are drilled at different diameters on the pressure plates thus enabling the device to be adapted to different dimensions of parts to be dismantled.The design and calculations of machine elements of the device were carried out under the design standard VOJNOTEHNIČKI GLASNIK / MILITARY TECHNICAL COURIER, 2017, Vol 65, No 1 (Ognjanović, 2008), (Standardi za meterijale mašinskih elemenata, JUS M.B1.050,DIN 601, JUS M. B1.051, 1980).
In the process of dismantling the parts, an autogenous welding set was used to heat the parts to be dismantled.
Positions (8)(9)(10)(11) in Fig. 1 indicate the parts to be dismantled.Position (8) denotes a threaded spindle which turns into the threaded hole at the head of the shaft or axle onto which the part is mounted.Position ( 9) is a pressure plate which pushes the part to be mounted into a specific position.Position (10) indicates a tapered roller bearing that reduces friction between the contact surfaces during assembly, and position (11) denotes a nut which pushes the conical bearing and the pressure plate on the threaded spindle, thus moving the part to be mounted.These operations require a considerable experience.The device for dismantling and assembling difficult-to-detach parts has found its first application in the Electro Industry Montenegro and in some companies in the Republic of Serbia.In the Electro Industry Montenegro, it is used in maintenance and overhaul of mini hydro power plants.The operations of overhaul of hydro electric power plants have been significantly improved.This universal device is used in all 18 mini hydro electric power plants.

Conclusion
The device for dismantling and assembling the parts of hard-toseparate mechanical assemblies on mechanical plants is an original and new technical solution (invention) in the maintenance and overhaul of mechanical systems, especially in off-road conditions where there are no other conditions for dismantling and mounting assemblies, such as specialized machine shops, overhaul institutes and others.
This device is portable, universal and very easy to use.It allows an easy, fast and efficient dismantling and assembling hard-to-separate parts large in size.Flanges or various types of metal hubs can have an external diameter up to 800 mm, inner diameters may be up to 250 mm, the size of the overlap (dosed components) to the axle or shaft may be up to 0.025 mm, and the length of engagement work on the axle can be up to 300 mm.This means that these parts are very complicated to disassemble and re-assemble.The device design is such that it prevents damage to parts during disassembling and reassembling.
The device has a wide range of applications.In the Electro Industry Montenegro, it is used to maintain mini hydroelectric power plants.In the Republic of Serbia, it is often used in repair of diesel electric generators for electric power supply backup.The users of diesel generating sets are many firms: Air Traffic Control, Airport Belgrade, Air Serbia, the Serbian Army and many other companies.
The application of this device has improved the technology of maintenance of mechanical installations.

Figure 3 -
Figure 3 -Schematic representation of a mini hydro power plant Рис. 3 -Схематическое изображение сооружения мини-ГЭС Слика 3 -Шематски приказ посторојења мини-хидроелектране In Fig.3, hard-to-separate assemblies are labelled: the position (A) indicates the generator assemblies, the position (B) marks the flywheel assemblies, bearings, and the flexible couplings of the ARPEX type-German manufacturer Flender, the position (C) is the multiplier with a flexible coupling type N-EUPEX A 480, German manufacturer Flender, the position (D) is the turbine part, and the position (E) denotes the turbine regulator.Fig. 4 presents the mounting of the metal parts of the flexible couplings N-EUPEX, onto one side of the multiplier set, and Fig. 5 presents the completed mounting of the ARPEX coupling onto the other side of the multiplier of the mini hydropower plant (Žegarac, 2009).