The coolant flow is, in a sense, a machine tool axis. After all, the flow can
be turned on and off by the control. True, this may make it a rudimentary axis,
but why not put this additional axis to work?
Using coolant, at least for its traditional roles of cooling and chip
removal, seems increasingly to be questioned. Dry and semi-dry machining can
help some shops eliminate coolant-related maintenance and disposal costs. On the
other hand, the fact that through-spindle coolant is now a commonplace feature
of machining centers has brought new possibilities to shops. The chance to
gundrill on machining centers (see the next article) illustrates the point. In
addition, developers of machining center accessories have found some clever ways
to use the through-spindle coolant for mechanical actuation.
Benz
(Charlotte, North Carolina) offers an example of such an accessory. The
company’s Universal Parallel Gripper is a coolant-operated workhandling device
that loads into the spindle like a toolholder. A spring closes the gripper,
while the pressure of the through-spindle coolant forces the gripper open. With
this device, the machining center spindle can grip and lift workpieces weighing
as much as 8 kilograms with the standard fingers, or as much as 40 kilograms if
the gripper’s fingers are form-fitted to the part.
Clearly, compared to other machining center workhandling systems, this
gripper has an important limitation. It relies on the machine itself for
movement, so it can’t travel beyond the machine’s work zone. Are there uses for
work handling that applies only within the machine tool’s travels? Benz
technical application specialist Mike Starnes says that in certain applications,
this simple device can deliver a high rate of return.
One such application is the machining of hex dies, or other part types in
which several workpieces are set up together for one machining cycle. When the
coolant-operated gripper is coupled with vises that can automatically release
the workpieces at the end of the cycle, the gripper can allow the machine itself
to gather all of these pieces and place them in a bin. This reduces the amount
of human labor involved in the process.
The gripper can also deliver value in precisely timed production operations
in which the number of seconds the operator spends on loading and unloading can
have a measurable effect on productivity. By lifting the finished part out of
the fixture automatically, the machining center can place the part where it will
be much easier for the operator to grab—shaving time off of the work the
operator has to do as every cycle ends.
MMS Online is a trademark of Gardner
Publications, Inc, copyright 1997-2008.
MMS Online and all contents are
properties of Gardner Publications,
Inc.
All Rights Reserved.
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