TESA MH3D, User Manual

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©2004 TESA Switzerland All Rights Reserved.
Page 2-6
User's Manual
MH3D
Bridge
The MH3D is a vertical, moving bridge type of CMM. The Bridge travels along
the Y-rail at a right angle to the front of the machine. It is of modular construc-
tion and consists of a left outboard leg, a right inboard leg and an X-Rail which
spans the two legs.
The left leg is an aluminum casting that results in a member
that is both structurally light and
stiff. The leg contains seven (7)
air bearings which provide
virtually frictionless movement
and support in the Y direction.
An air harness contains the lines
for the air bearings as well as for
the axes air switches located at
the front of the left leg.
The air switches control the
lines from the manifold to the
preload bearings for each axis.
On the MH3D an axis can be
locked by toggling the air switch
off (down) and deflating the
preload bearings for that axis. On the MH3D the air switches are additionally
used to engage or release the fine adjust mechanisms. These mechanisms,
mounted on the X, Y and Z axes, are used for precise adjustment of the individual
axes.
The Y-axis encoder is mounted in the lower part of the leg, beneath an access
plate. Elastomeric bumpers on the leg act as stops when contacting the base at the
end of travel.
The right leg is also an aluminum casting and contains two (2) air bearings for
virtually frictionless movement. The bearings are preloaded for improved
accuracy of the MH3D.
The X-rail is a lightweight, hardcoated, aluminum that spans the two legs and
serves as both support and guide for the X-Z carriage. The X-rail is both bolted
and epoxied to the left leg and bolted to the right leg. A cable track is provided for
the X-axis loop to reduce hysterisis and improve accuracy.
The X-axis measuring scale is recessed into the back side of the X-rail. The scale
is protected by a cover. The top and front sides of the rail are the positive sides.
Note: Although the guide rails are hardcoated and anodized, they can be
damaged by a bang or bump from a hard object. Never place objects against the
rails and avoid lifting over the rails when loading or unloading parts.