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Conventionally, Worm reduction gear sets
have always been made on dedicated gear hobbing / shaping
machines
using dedicated tooling & cutters. These machines are
excellent for mass production of gear sets. However, small
companies can not afford to invest in these machines especially
if their core product is something other than gear manufacture.
Due
to the wide spread usage of 4 and 5 axis VMC’s &
turning centers with C & Y axis, it is now possible,
with the right software, to make any worm reduction gear
set.
There is no need for any special tooling or cutters, all
that is required is a standard end mill. Manufacture of
large size gears is possible on relatively small multi axis
VMC’s & Turning Centers with C & Y axis. Hence
even mass production costs for larger gear sets actually
work out cheaper by this novel method of manufacture!
Furthermore,
in the case of special components, the gear profile can
be machined as part of the component itself, especially
on a CNC lathe with C & Y axis, along with the other
turning operations! No need to machine splines / keyways
or fasten the gear on to your driving / driven shaft. |
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Our service
is aimed at those machine shops that do not have gear hobbing
machines & thread whirling machines, but own 4 & 5 axis
VMC's or CNC turning centers / CNC lathes with C & Y axis.
This is an
ideal method of manufacture of Prototypes, small / medium batches,
replacements etc. The tool paths are extremely accurate &
optimised for maximum productivity, keeping the cutter engaged
with the component with minimum air cutting.
Our service is aimed at those machine shops that do not have gear
hobbing machines & thread whirling machines, but own 4 &
5 axis VMC's.
Our method of manufacture involves ‘swarf’ cutting
(the diameter of the tools generates the desired profile as per
the figure below). The advantage of this system is that the tip
of the tool (red portion) does the roughing operation (equal to
depth of cut per pass) while the portion above the tip of the
same tool (green portion) does finishing of the profile, by removing
a minute portion of material left behind in the previous pass,
by the red portion of the tip of the tool. This is possible due
to the involute profile of the Worm wheel teeth. Hence by simultaneously
using different parts of the same tool for roughing & finishing
operations, the cycle time is minimized. Also, a slight amount
of wear that typically occurs on the tip of the cutter does not
affect the profile. Similarly, slight error in Z offset of the
tool does not affect the profile.
The
corner radius that is inherent in the process of hobbing can also
be replicated by using an end mill cutter with suitable corner
radius as per the figure below.
Our
method of tool path generation is directly created from the raw
data like center distance, ratio, module, Diameteral factor &
cutter diameter. We do not first create the profile & use
a CAM post processors to generate the profile. Hence, there are
no losses in accuracy due to conversions in CAD formats etc. We
have developed our own software that creates very accurate tool
paths & we only simulate the tool paths to verify the result.
We
are offering any of the following services for Worm wheel &
Worm shaft manufacture on VMC.
1)
Worm wheel profile defined as points in Excel / Text format.
2) Worm wheel / Worm shaft profile defined as surface in IGES
format
3) Part program in G codes required to manufacture the Worm wheel
(4 axis) / Worm shaft (5 Axis)
4) 3D Simulation of the machining as above with IGES file of machined
component.
5) Physical manufacture of the components / prototypes.
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