Accuracy |
Finished
forging accuracy depends on how accurately the blanks are sheared
off. If blank volume isn't right on, the result will be either under
filling of parts or over-packing of dies.
Hotmatics use an open-type shearing knife, i.e., two blades with semicircular
cutting edges. One blade is mounted in the die block at the same level
as the dies; the other rides on the shearing slide, moving back and
forth at each stroke to cut off a piece of the bar. |
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TWO
PAIRS OF FEED ROLLS MOVE THE BARS ALONG AGAINST THE SHEARING STATION
BAR STOP
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Ejecting
Bar Ends |
Though
a relatively simple job, ejecting the bar ends nevertheless demands
a high degree of alertness and concentration on the operator's part.
This is why most installations are now being equipped with ESA control,
an electronic system that eliminates bar ends automatically. |
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Bar
Ends |
Bar
ends are ejected immediately after cut-off. The operator presses a
button on the control desk to release the holding finger on the shearing
slide, allowing the bar end to drop clear. A preselection mechanism
makes sure the finger opens only when the shearing slide is in the
correct position. At the same time, an automatic pusher pin kicks
the end out of the shear blade. |
Prevent
Distortion |
To
prevent the blank from being distorted by the pressure of the shear
blade, a cam-controlled gripper jaw clamps the bar firmly against
the stationary blade in the die block during cut-off.
The cut-off length can be adjusted from the control desk during operation.
Pressing the button 'cut-off longer' or 'cut-off shorter' moves the
bar stop forward or back at the right instant. The length set is shown
on a digital display unit. |
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SHEARING
STATION WITH BAR STOP, SHEAR BLADE AND HOLDING FINGER
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