Nexen RPG25A-GE486T 966740 - Manual (Page 7)

7 FORM NO. L-21235-G-0413
A
Rack
B
0.03 mm A
0.03 mm B //
0.03 mm
A
//
0.03 mm
B
0.03 mm
A
//
Parallel
Rack
90˚ ± 0.1°
Pinion
Shaft
GENERAL DESIGN GUIDELINES
Figure 2 Tolerances
In order to minimize backlash , obtain the highest positional
accuracy, and minimize wear on the rack, the RPS system
must be installed on a rigid, straight, flat mounting surface
with the tolerances shown in Figure 2.
The following requirements must be met to ensure proper
RPS operation:
a) Mount a linear guide rail on a surface parallel to the
RPS rack mounting surface with the same flatness as
the rack mounting surface ash shown in Figure 2.
b) The pinion shaft must be parallel (0.03 mm [0.001 in])
to the rack mounting surface opposite the rack teeth
and the angle between the pinion shaft and the face
of the rack must be 90° ±0.1° maximum as shown in
Figure 1).
Figure 1 Pinion Alignment Requirements Systems may be mounted at any angle as long as the rack,
guiding system and mounting surface remain parallel with
the shaft at a 90° angle from the rack.
This distance must remain
parallel within 0.03 mm
[0.001 in]
Additional dimensional detail can be found in
Nexen’s product drawings.
The rack must sit on a step at
least one half the width of the
rack for proper support. The
rack should not be supported
by fasteners alone. Pinning the
rack to its mounting surface is
not recommended. Rack
W
1/2 W
c) The pinion shaft must be supported adequately to
ensure full contact of the pinion rollers along the face
of rack teeth.
Figure 3 Rack Support Requirements
INSTALLATION
The mounting surface for both the rack and the guiding
system must be parallel within the specifications shown
in Figure 2. This parallelism requirement is best achieved
by machining the mounting locations for both the guiding
system and rack in the same machining operation. (Refer
to PROPER SYSTEM ALIGNMENT and Figures 1 and 2
for Possible Mounting Configurations.) Nexen recommends orienting the rack teeth downward or
to the side so it minimizes the possibility of debris collecting
on the teeth and causing meshing interference. The rack
has 5 reference surfaces and includes all sides except the
side with the product number. The non-reference face
with the product number should not be placed against
the machine bed surfaces. Any rack ends that have been
cut must be located at the end of the run; the pinion must
not cross cut rack ends.