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Two-Hand Controls can be used as safeguarding
devices in the single stoke mode of operation on part revolution
clutch presses. Similar to the two-hand
trip, this device keeps the operators hands away from the point of
operation during the entire machine stroke.
| Two-Hand
Control Regulations |
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Press operations requiring more than one
operator must provide each operator with separate two hand controls
where each set must be engaged to complete a machine stroke.
The removal of a hand from any control button will stop the slide.
[1910.217(c)(3)(vii)(a)]
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Each two-hand control must meet the construction requirements
of paragraph (b)(7)(v).
[1910.217(c)(3)(vii)(b)]
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Press operation using two-hand
controls
Click on image to view video
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| Single
Stroke Requirements |
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Each hand control must be protected against
unintended operation and arranged by design, construction,
and/or separation so that the concurrent use of both hands is
required to trip the press. [1910.217(b)(7)(v)(a)]
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The control system must be designed to permit
an adjustment which requires concurrent pressure from
both hands during the die closing portion of the stroke. [1910.217(b)(7)(v)(b)]
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The control system must incorporate an
anti-repeat feature. [1910.217(b)(7)(v)(c)]
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Press operation requires separate
sets of two-hand
controls for two operators
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The control systems must be designed to require
the release of all hand controls before an interrupted
stroke can be resumed. This requirement pertains only to those
single stroke, two-hand controls manufactured and installed on
or after August 31, 1971. [1910.217(b)(7)(v)(d)]
Please also see the
formula
used to compute the minimum safety distance on mechanical power
presses to meet the ANSI B11.1 Press Safety Standard or
information on stop-time
measuring units.
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| How
Does It Work? |
Two-hand control, as a point of operation
safeguarding device for press brakes, is ideal for short-run
job-shop operations. Piece parts can vary from quite small to very
large.
| STEP 1 |
By depressing the control buttons, the
operator initiates the press brake stroke.
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| STEP 2 |
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The operator must hold the buttons until the slide completes its downward travel. If the operator removes
a hand
from one of the controls, the slide will stop. In the single
stroke or Hi/Lo mode, the slide will make one complete
stroke.
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Example of two-hand control operation
Click on image to view
animation
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| STEP 3 |
In the sequence mode, the slide will
automatically stop at a preset position 1/4" or
less above the work piece. This position is
adjustable for different feed-line heights or material
thickness.
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| STEP 4 |
If the work piece is not already placed in the
die, it may be inserted at this time.
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| STEP 5 |
The two-hand control or the foot switch is now
re-initiated , causing the slide to continue through the
bottom of the stroke and finishing at top dead center (TDC).
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