IMS ENGINEERING COLLEGE,GHAZIABAD (U.P) Department of Mechanical Engineering TOPIC:- DYNAMOMETER Submitted by :- Ambesh kumar Roll no Batch :-ME-1 ( )

DYNAMOMETER

Definition  A dynamometer is a device which measure accurately the cutting forces encountered during the cutting process.  In most metal cutting dynamometers the total force is determined by measuring,during metal cutting,the deflection or strain in the elements supporting the cutting tool & dynamometer design should be such that it gives strains or displacement large enough to be measured accurately  Dynamometer is designed such that it measures all the three components in a set of rectangular co-ordinate. While measuring these three forces,the dynamometer should be designed that force in X-direction should give no reading in Y & Z direction

DIFFERENT TOOL DYNAMOMETERS COMMONLY USED ARE : 1.MECHANICAL DIAL GAUGE TYPE 2.STRAIN GUAGE TYPE

MECHANICAL DIAL GAUGE TYPE DYNAMOMETER Fig.1 simple 2 component cutting force dynamometer for use on a lethe

MECHANICAL DIAL GAUGE TYPE DYNAMOMETER  Fig 1 shows a simple tyoe of 2 component force dynamometer, where the cutting tool is supported at the end of cantilever.  The vertical and horizontal components of the deflection of the cantilever under the action of the resultant tool force are taken as a measure of the two force component,i.e. Ft & Fr.  The dial gauge A gives a measure of cutting force (Ft) and dial gauge B gives a measure of thrust force(Fr).  The two components Ft & Fr of the resultant tool force measured with a dynamometer, may be used to calculate many important variable in the process if continuous chip formation.

STRAIN GUAGE DYNAMOMETER Fig:2 Resistance strain gauge type dynamometer

STRAIN GUAGE DYNAMOMETER  In orthogonal or two dimensional cutting,the resultant force applied to the chip by the tool is usually determined,in experimental work,from the measurement of two orthogonal component: 1.Cutting force Ft or Fc 2.Thrust force Fr  Fig 2 shows two component electrical strain gauge dynamometer.  It consists of two half ring arranged to support the cutting tool, the flat sides serving to simplify the problem of mounting the strain gauge on the ring.  An electrical strain gauge is essentially a wound length of resistance wire (0.025 mm dia) duly enveloped

 The strain gauge is bounded with adhesive onto the surface under investigation.The resistance of wire is increased by stretching due to the direct increase in length.  If the surfaceis compressed, wire length also compresses and the resistance of wire is decreased.This change in resistance of the strain guage is measured by a Wheatstone bridge.  Formulae are available to convert these reading into change in length,strain and hence stresses to which surface or strain gauges were subjected.  Two sets of strain gauge,connected in two separate Wheatstone bridges are mounted as follows.

 To measure the vertical component of the applied force,gauge 1 to 4 are mounted on the horizontal centre line of the ring ; when a vertical laod is applied,gauges 1 & 3 will record compressive strain and gauge 2 & 4 record tensile strain.

Pictures of different types of dynamometer