design of abrasive cut off machine

Om sakthi ADHIPARASAKTHI ENGINEERING COLLEGE MELMARUVATHUR

DESIGN & FABRICATION OF ABRASIVE CUT-OFF MACHINE.  PROJECTGUIDE :  Mr. D.SIVAKUMAR,M.E.,M.I.S.T.E.,(Phd.) Assistant Professor. DEPT.OF MECHANICAL ENGINEERING. MEMBERS:

1.C.DURENDRAN 2.R.PARTHIBAN 3.C.PRABU KRISHNAN 4.S.SIVA(17.5.89)

: : : :

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ABSTRACT  A cutoff is one of the most commonly used machinery in the manufacturing process, and almost every workshop has one. It is easy to use, maintainable and cost effective.

ABSTRACT contd… Abrasive cut off machine is one which uses the abrasive wheel to cut the materials. The basic calculations are made using mathematical relations. The designing is carried out and then fabrication is done. Finally the machine is made to work and the faults are corrected.

CONCEPT-1 In the concept the hinge point is situated at the rear of the machine. Pulleys with V-belts will be used to transmit power from the motor to the arbor shaft.

CONCEPT-2 In this concept the hinge is located slightly in front of the motor (if the cutting disc is said to be the front), this will act like a “seesaw”. When the machine is not busy cutting steel, the cutting disc will be kept in the air due to the weight of the motor at the back. Pulleys and a V-belt will be used for power transmission.

CONCEPT-3

Fixing the cutting disc to the motor shaft directly.

CONCEPT EVALUATION CON.1       

Simplicity Practicability Manufacturability Maintainability Yielding Possibility Safety Cost

4 5 4 4 4 4 3

CON.2 4 3 4 4 4 3 3

CON.3 4 2 5 5 2 1 5

BLOCK DIAGRAM  We choose concept-1.

SPECIFICATION

PART DIAGRAMS PULLEY SHAFT AND COUPLING….

ABRASIVE WHEEL

BASE

DESIGN CALCULATION DESIGN OF SHAFT 1 Material Used :45C8 [Refer PSG DB page no.1.9] TENSILE STRENGTH=700N/mm² YIELD STRENGTH=350N/mm² TORQUE=(3.14×t×d³)/16 TORQUE ON SHAFT: P=(2×3.14×N×T)/60 3.75×10³=(2×3.14×2950×T)/60 T=12.138Nm=12.138×10³Nmm.

Shear stress t=ultimate strength/factor of safety. FOS=4. t=700/4=175N/mm². [FOS>2.15 [Refer PSG DB page no.7.22] T=(3.14×t×d³)/16 12.138×10³=(3.14×175×d³)/16 d=7.06mm Normally we use shaft of diameter 20-25mm. DESIGN OF SHAFT-2 TORQUE ON SHAFT: P=(2×3.14×N×T)/60 3.75×10³=(2×3.14×4000×T)/60 T=8.95Nm=8.95×10³Nmm. T=(3.14×t×d³)/16 8.95×10³=(3.14×175×d³)/16 d=6.38mm Normally we use shaft of diameter 20-25mm.

DESIGN OF V-BELT AND PULLEY N1=4000rpm N2=2950rpm P=3.75KW SELECTION OF BELT: For P=3.75kw [Refer PSG DB page no.7.58] Select B type belt. Small pulley diameter: For B dpmin=125mm [Refer PSG DB page no.7.62] demax=dpmax×Fbmax de=equivalent pitch dia dp=pitch dia of smaller pulley Fb=small dia factor

For demax [Refer PSG DB page no.7.62] demax=175mm Speed ratio:i=N1/N2 i=4000/2950=1.35 For i=1.35Fb=1.1 [Refer PSG DB page no.7.62] demax=dpmax×Fbmax 175=1.1×dpmax dpmax=159mm For standard dia [Refer PSG DB page no.7.20 R20 series] It should be between dpmin & dpmax dp=140mm CENTRE DISTANCE : C/D=1(assume) N1/N2=D/d D=1.35×140=189mm D=200mm For standard dia [Refer PSG DB page no.7.20 R20 series]

C/D=1 C=200mm [Refer PSG DB page no.7.61] Cmin=0.55(D+d)+T For T [Refer PSG DB page no.7.58] Normal thickness T=11mm Cmin=0.55(200+140)+11 Cmin=198mm Cmax=2(D+d) [Refer PSG DB page no.7.61] Cmax=2(200+140)=680mm Calculated value of C lies between Cmin & Cmax LENGTH OF BELT: [REFER PSG DB P.NO:7.61] L=2C+[(3.14/2)×(D+d)]+[{(D-d) ²}/4C] =2×200+[(3.14/2)×(200+140)]+[{(200-140) ²}/(4×200)] Pitch length: L=938.57mm NOMINAL INSIDE LENGTH: [Refer PSG DB page no.7.59] For nominal inside length corresponding to nominal pitch length(965mm) is 1008mm. Length correction factor Fc=0.83 [Refer PSG DB page no.7.59]

ANGLE OF CONTACT: Θ=180-[60{(D-d)/C}] =180-[60{(200-140)/200}] Θ =162deg angle correction factor Fa=(v-v belt) For Θ=163 Fa=0.96 [Refer PSG DB page no.7.68] For service factor [Refer PSG DB page no.7.69] medium duty Fs=1.1(for up to 10 hrs) POWER RATING: [Refer PSG DB page no.7.62] KW=[{0.79×S-0.09}-(50.8/de)-{(1.32×10^(-4) ×(S²)}]S S=(3.14×d×N)/60 =(3.14×4000×140)/(60×1000) S=29.32m/s. de=dp×Fb =140×1.1 de=154mm

KW=[[{0.79× (29.32)-0.09}-(50.8/154)-{(1.32×10-4 ×(29.32²)}] ×29.32] KW =4.04 NUMBER OF BELTS: [Refer PSG DB page no.7.70] No. of belt=(P×Fa)/(KW×Fc×Fd) =(3.75×1.1)/(4.04×0.83×0.96) =0.98 ~1 FINAL CENTRE DISTANCE: [Refer PSG DB page no.7.61] C=A+{[(A²)-B]1/2} A=(L/4)-(3.14× [(D+d)/8]) =(1008/4)-(3.14× [(200+140)/8]) A=118.48mm B=[(D-d) ²]/8 =[(200-140) ²]/8 B=450mm

C=A+{[(A²)-B]1/2} C=118.48+{[(118.48²)-450]1/2} C=235mm

SPECIFICATION: 1) 2) 3) 4) 5) 6)

Type of drive=V-belt Belt used =B965-IS2494 Number of belt=1 Smaller pulley diameter=140mm Larger pulley diameter=200mm Centre distance=235mm

VICE  Vice is to hold the work piece in position.

PROVISION FOR ANGULAR CUT This part is to cut the work piece angularly.

TOP VIEW

STOPPERS Stoppers provided for the safety and to provide limits.

MOTOR STOPPER

SPRING TO RETAIN THE MOTOR BACK TO ORIGINAL POSITION.

MOTOR BED

PULLEY

MOTOR COUPLED WITH THE PULLEY

BELT USED TO CONNECT MOTOR PULLEY WITH THE ABRASIVE WHEEL PULLEY

PHOTOGRAGH SHOWS THE LEVERAGE HINGE POINT AND THE MOTOR BED

ABRASIVE CUTTING DISC

WASHERS & NUT TO GRIP AND HOLD THE CUTTING DISC IN POSITION

CUTTING DISC HOUSING

HANDLE TO OPERATE

PARTLY ASSEMBLED VIEW

Right Side View

Left Side View

Front View

Front View

Rear View

Top View

Project video

CONCLUSION & FUTHER DEVELOPMENT 

This presentation has discussed the idea of abrasive cut off machine and demonstrating the functionality and performance of the abrasive cut off machine. An overview of the machine has been discussed. A detailed design calculation has been described, offering an economical safer and rather simple, yet reliable, way to meet the requirement of a workshop.

CONCLUSION & FUTHER DEVELOPMENT contd..  It is important to mention that the machine can perform more complex tasks by applying simple modifications on the design. For instance, mounting different sensors in the machine would inform the user of changes in the behavior of the material while cutting.  In addition we can modify the operation from manual to automatic for better performance and to reduce the time for operation

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