DOM MANUAL / B-TECH / MECHANICAL / KUK - TO PERFORM THE EXPERIMENT THE UNBALANCED COUPLE AND FORCE.

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AIM: TO PERFORM THE EXPERIMENT THE UNBALANCED COUPLE AND FORCE.

DESCRIPTION: THE APPARATUS BASICALLY CONSIST OF A STEEL SHAFT MOUNTED IN BALL BEARING IN A STIFF RECTANGULAR MAIN FRAME. A SET OF SIX BLOCKS OF DIFF. WEIGHTS IS PROVIDED AND MAY BE CLAMPED IN ANY POSITION ON THE SHAFT AND ALSO BE EASILY DETACHED FROM THE SHAFT.
A DISC CARRYING A CIRCULAR PROTECTOR SCALE IS FITTED ON ONE SIDE OF THE RACTANGULAR FRAME. SHAFT CARRIES A DISC AND RIM OF THE DISC IS GROOVED TO TAKE A LIGHT CORD PROVIDED WITH TWO CYLINDRICAL METAL CONTAINERS OF EXACTLY THE SAME WEIGHT.
A SCALE IS FITTED TO THE LOWER MEMBER OF THE MAIN FRAME AND WHEN USED IN CONJUNCTION WITH THE CIRCULAR PROTACTOR SCALE, ALLOWS THE EXACT LONGITUDINAL AND ANGULAR POSITION OF EACH ADJUSTABLE BLOCK TO BE DETERMINED.
THE SHAFT IS DRIVEN BY A 230 VOLTS SINGLE PHASE 50 CYCLES ELECTRIC MOTOR, MOUNTED UNDER THE MAIN FRAME, THROUGH A BELT.
FOR STATIC BALANCING OF INDIVIDUAL WEIGHTS THE MAIN FRAME IS SUSPENDED TO THE SUPPORT FRAME BY CHAINS AND IN THIS POSITION THE MOTOR DRIVING BELT IS REMOVED.
FOR DYNAMIC BALANCING OF THE ROTATING MASS SYSTEM THE MAIN FRAME IS SUSPENDED FROM THE SUPPORT FRAME BY TWO SHORT LINKS SUCH THAT THE MAIN FRAME AND THE SUPPORTING FRAME ARE IN THE SAME PLANE.
PROCEDURE
STATIC BALANCING
REMOVE THE DRIVE BELT. THE VALUE OF WR. FOR EACH BLOCK IS DETERMINED BY CLAMPING EACH BLOCK IN TURN ON THE SHAFT AND WITH THE CORD AND CONTAINER SYSTEM SUSPENDED OVER THE PROTACTOR DISC, THE NUMBER OF STEEL BALLS, WHICH ARE OF EQUAL WEIGHT, ARE PLACED INTO ONE OF THE CONTAINERS TO EXACTLY BALANCE THE BLOCK ON THE SHAFT. WHEN THE BLOCK BECOMES HORIZONTAL, THE NUMBER OF BALLS ‘N’ WILL GIVE THE VALUE OF WR. FOR THE BLOCK.

FOR FINDING OUT ‘WR’ DURING STATIC BALANCING PROCEED AS FOLLOWS:
1.      REMOVE THE BELT.
2.    SCREWED THE COMBINED HOOK TO THE PULLEY WITH GROOVE (THIS PULLEY IS DIFFERENT THAN THE BELT PULLEY).
3.      ATTACH THE CORD – ENDS OF THE PANS TO THE ABOVE COMBINED HOOK.
4.      ATTACH THE BLOCK NO. 1 TO THE SHAFT AT ANY CONVENIENT POSITION AND IN VERTICAL DOWNWARD DIRECTION.
5.  PUT STEEL BALLS IN ONE OF THE PANS TILL THE BLOCK STARTS MOVING UP (UPTO HORIZONTAL POSITION).
6.     NUMBER OF BALLS GIVE THE ‘WR’ VALUE OF BLOCK 1. REPEAT THIS 2-3 TIMES AND FIND N  THE AVERAGE NO. OF BALLS.
7.      REPEAT THE PROCEDURE FOR OTHER BLOCKS

 STATIC & BALANCING OF 4 BLOCKS.
OBTAIN STATIC BALANCE OF A SET OF FOUR BLOCKS WITH UNBALANCE AS SHOWN BY PROPERLY POSITIONING THEM IN ANGULAR AND LATERAL POSITION ON THE SHAFT.

NO.
UNBALANCE (WR. PRODUCT)
1.
124
2.
122
3.
120
4.
117


FORCE POLYGON
ANGULAR POSITION OF NO. 3 BLOCK IS OBTAINED FROM THE FORCE POLYGON AND ITS MAGNITUDE IS ALSO OBTAINED
F= 70 ADJUST ALL ANGULAR AND LATERAL POSITION PROPERLY AND FIND THAT THE SHAFT ROTATES WITHOUT VIBRATION.

FORCE POLYGON
S.NO.
WT. NO.
WT.
DISTANCE
COUPLE
ANGLE
1
4
124
0
0
189
2
3
122
2
244
0
3
2
120
4
480
33
4
1
117
6
702
206

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