10-06-2017, 06:47 AM
of quick return mechanism in shaper machine in ppt presentation
Introduction
The Whitworth quick return mechanism converts rotary motion into reciprocating motion, but unlike the crank and slider, the forward reciprocating motion is at a different rate than the backward stroke. At the bottom of the drive arm, the peg only has to move through a few degrees to sweep the arm from left to right, but it takes the remainder of the revolution to bring the arm back. This mechanism is most commonly seen as the drive for a shaping machine.
Construction and Working
In this mechanism the page link CD (link2) forming the turning pair is fixed
The driving crank CA (link3) rotates at uniform angular speed
The slider (link4) atteched to the crank pin at A slides along the slotted bar PA (link1) which osicllates at a pivoted point D
The connecting rod PR carries a ram at R to which a tool is fixed
When the driving crank CA moves from the position CA1 to CA2 through an angle in the clockwise direction the tool moves from the left hand end
Now when the driving crank moves from position CA2 to CA1 through the angle in the clockwise direction the tool moves back from right hand end
since crank page link CA rotates at angular velocity therefor time taken during the cutting stroke(forward stroke) is more than the time taken duringthe return stroke
Introduction
The Whitworth quick return mechanism converts rotary motion into reciprocating motion, but unlike the crank and slider, the forward reciprocating motion is at a different rate than the backward stroke. At the bottom of the drive arm, the peg only has to move through a few degrees to sweep the arm from left to right, but it takes the remainder of the revolution to bring the arm back. This mechanism is most commonly seen as the drive for a shaping machine.
Construction and Working
In this mechanism the page link CD (link2) forming the turning pair is fixed
The driving crank CA (link3) rotates at uniform angular speed
The slider (link4) atteched to the crank pin at A slides along the slotted bar PA (link1) which osicllates at a pivoted point D
The connecting rod PR carries a ram at R to which a tool is fixed
When the driving crank CA moves from the position CA1 to CA2 through an angle in the clockwise direction the tool moves from the left hand end
Now when the driving crank moves from position CA2 to CA1 through the angle in the clockwise direction the tool moves back from right hand end
since crank page link CA rotates at angular velocity therefor time taken during the cutting stroke(forward stroke) is more than the time taken duringthe return stroke