Pneumatic Vice
An engineer's vise, also
known as a metalworking bench vise or fitter's vise, is used in metalworking applications. The jaws are made of
soft or hard metal. The vise is bolted onto the top
surface of the bench with the face of the fixed jaws just forward of the front
edge of the bench. The bench height should be such that the top of the vise
jaws is at or just below the elbow height of the user when standing upright.
The vise may include other features such as a small anvil
on the back of its body.
The nut in which the screw turns may
be split so that, by means of a lever, it can be removed from the screw and the
screw and moveable jaw quickly slid into a suitable position at which point the
nut is again closed onto the screw. The disadvantage to this system is lower
precision, as compared to a solid screw system. Vise screws are usually either
of an Acme thread form or a buttress thread.
Those with a quick-release nut use a buttress thread. Some vises have a
hydraulic or pneumatic screw, making setup not only faster, but more accurate
as human error is reduced.[citation needed]
For large parts, an array of regular
machine vises may be set up to hold a part that is too long for one vise to
hold. The vises' fixed jaws are aligned by means of a dial indicator
so that there is a common reference plane.
For multiple parts, several options
exist, and all machine vise manufacturers have lines of vises available for
high production work:
·
The first step is a two clamp vise,
where the fixed jaw is in the center of the vise and movable jaws ride on the
same screw to the outside.
·
The next step up is the modular
vise. Modular vises can be arranged and bolted together in a grid, with no
space between them. This allows the greatest density of vises on a given work
surface. This style vise also comes in a two clamp variety.
·
Tower vises are vertical vises used
in horizontal machining centers. They have one vise per side, and come in
single or dual clamping station varieties. A dual clamping tower vise, for
example, will hold eight relatively large parts without the need for a tool
change.
·
Tombstone fixtures follow the same
theory as a tower vise. Tombstones allow four surfaces of vises to be worked on
one rotary table pallet. A tombstone is a large, accurate, hardened block of
metal that is bolted to the CNC pallet. The surface of the tombstone has holes
to accommodate modular vises across all four faces on a pallet that can rotate
to expose those faces to the machine spindle.
·
New work holding fixtures are
becoming available for five-axis machining centers. These specialty vises allow
the machine to work on surfaces that would normally be obscured when mounted in
a traditional or tombstone vise setup