Presentation on theme: "IMS ENGINEERING COLLEGE,GHAZIABAD (U.P) Department of Mechanical Engineering TOPIC:- DYNAMOMETER Submitted by :- Ambesh kumar Roll no. 1214340021 Batch."— Presentation transcript:
IMS ENGINEERING COLLEGE,GHAZIABAD (U.P) Department of Mechanical Engineering TOPIC:- DYNAMOMETER Submitted by :- Ambesh kumar Roll no. 1214340021 Batch :-ME-1 (2012-2016)
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.