SHRI RAMDEOBABA COLLEGE OF ENGINEERING & MANAGEMENT

INDUSTRIAL ENGG. DEPT.

Metal Removal Process

ASSIGNMENT

Grinding MechanismCNC and Centerless

Grinding Machine

-Faizan Ali Sayyed 33

What is CNC Machine? Computerized Numerical Control Comprises of the computer in which the

program is fed for cutting of the metal of the job as per the requirements

Components of CNC Machine Coding Input device MCU Drive System Machine tool Feedback System

Functions of CNC  Control function (control the axes) Interpolation function(trajectory) Feed function Spindle function (spindle speed) Auxiliary functions(stopping and steering)  Tool function( select desired tool) Graphic display function(CRT or LCD)  Self-diagnostic function (caution from failure) Communication function (to adapt FMS)

Motion of grinding wheel Grinding wheel can follow any linear

path in X Y Z direction Along with that it can rotate about a

fixed axis of rotation only in one direction

But the axis of rotation can be adjusted in three-dimensions

The types of work pieces and operations typical of grinding: (a) cylindrical surfaces, (b) conical surfaces. (c) fillets on a shaft, (d) helical profiles, (e) concave shape, (f) cutting off or slotting with thin wheels, and (g) internal grinding.

Recirculating Ball Screw Mechanism for Table movement Widely used in CNC tools The thread form used is Gothic arch

The balls rotate between the screw thread and the nut, and recycle around the thread.

The efficiency of the recirculating ball screws is about 90%

Movement is obtained by the rolling motion of the balls between the screw and the nut

The balls put pressure on opposite sides to allow bi-directional motion of table

The table can move in 2 perpendicular axes

Stepper MotorIt is used in Grinding Machines downfeeding grinding wheel automatic wheel dressing

Diagram of a typical stepper motor

Stepper Motor is used to control the axis of the rotating grinding machine

The toothed electromagnets present inside the motor gets attracted to the gear teeth, when given charge.

This divides the motion into no. of equal steps

Optical encoder is used in the feedback system to observe and control the rotary motion of the grinding wheel

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