The objective of this project is to design and fabricate a Bushed-pin type flexible coupling. Its function is to transmit power between shafts that are partially misaligned and it also absorbs shock loads. It employs rubber bushes fitted over pins that transmit torque by means of shear resistance. Design will be carried out by choosing a prime mover having an output of 5000 W and a speed of 750 rpm.
PHOTOGRAPHIC VIEWS OF THE COUPLING
AUTOCAD DIAGRAM OF THE COUPLING
LIST OF COMPONENTS USED
It is keyed to the input shaft coming from the prime INPUT FLANGE : mover and transmits power to the pins through the rubber bush. OUTPUT
FLANGE It : obtains power from the pins by means of shear resistance, is keyed to the output shaft.
The pins here are nothing but unthreaded PINS : bolts. They connect the two flanges and also maintain a clearance between the two shafts for angular misalignment. These rubber bushes are provided to absorb shock R UBBER BUSHES : loads, torsional vibrations and angular misalignments. They are provided with brass linings to reduce wear.
Design of the Bushed-pin Coupling
aterials Materials
chosen to carry out design of coupling : :
SHAFTS :Since shafts are subjected to torsional shear stresses, ³PLAIN CARBON STEEL´ is chosen on strength basis. Grade : 40C8 , Yield stress : 380 N/mm2 , O FS : 2 KEYS : Subject to shear and compressive stresses. b ending stresses. PINS : Subject to shear and bending Grade : 30C8 , Yield stress : 400 N/mm2 , O FS : 2 FLANGE : Manufactured by casting due to their complex shape. Grade : GCI FG200 , Ultimate stress : 200 N/mm2, FOS : 6
DESIGN SYNOPSIS
The design calculations were carried out such that the ³ Shaft governed the design´ Using Initially assumed values of Power and prime mover speed, the shaft diameter was obtained as 16mm. Now by using data from P SG Data book (page 7.108, table 2) the various parameters were obtained. Further , actual stress values were calculated for the keys, pins, bushes and flanges. The design was calculated to be lesser than the permissible values of design, hence the design is ³safe´.
DESIGN OUTPUT DIAGRAM DRAWN USING AUTOCAD
DESIGN OUTPUT PARAM PARAMETERS ETERS
16mm SHAFT DIAMETER : OUTER FLANGE DIAMETER : 100 mm 30mm HUB DIAMETER : 63mm PCD of PINS 30mm LENGTH OF HUB : 10mm PIN DIAMETER : 20mm LENGTH OF BUSH : : 12mm PR OTECTIVE LAYER LAYER : THICKNESS 4 NUMBER OF PINS : 22mm DIAMETER OF BUSH : : 2mm CLEARANCE :
ADVANTAGES
It can tolerate 0.5mm of lateral or axial misalignment and 1.5 degrees of angular misalignment. Prevents transmission transmission of shock from one shaft to the other and absorbs vibrations. vibrations. It can be used for transmitting high torques. It is simple in construction and easy to assemble and dismantle. It is easy to design and manufacture the coupling. For the same size of shafts, flexible bush coupling has larger number of bolts or larger pitch circle diameter than rigid type coupling. This reduces the force acting on the pins and lowers bearing pressure on the rubber bush.
DISADVANTAGES
The cost of flexible coupling is more than that of rigid coupling due to additional parts. It requires more radial space compared with other types of coupling. Maximum
allowable peripheral speed of the coupling is 30m/s.
