Material
All of our Hirth Gears are made of a special Chromium-Molybdenum
(41xx Series) steel.
MANUFACTURING
Milling of Teeth
The gears are rough machined, thermally annealed, semi-finished
machined with a roughing of the Hirth Teeth and finally thermally
stressed relieved.
Grinding of the Teeth
The diameters and faces are rough ground with the teeth being
induction hardened to a RC58 +2 surface hardness using Danobat
CNC grinders.
Grinding of the Surface
The gears are precision ground again on their faces, both inside
and outside diameters using ELB and Voumard grinders.
Final Grinding & Inspection
The Hirth teeth are semi-finished ground, unclamped and then reclamped
for a final ground holding extreme accuracies on new Magerle CNC
grinder.
Matching Hirth type face gears are ground parallel to .002mm (.00008")
or better using ELB grinders and inspected on Rank Taylor Hobson
and Sip Mul 300 measurement machines.
KEY BENEFITS
Product Features
Standard indexing of accuracies of +3 arc seconds. Special accuracies
of +1 arc seconds are available upon request.
RESISTANT TO WEAR
Case hardened teeth using chromium-molybdenum steel, make our gears
resistant to wear.
POSITIVE LOCKING
Numerous teeth provide rigid locking allowing for great machining
forces to be applied to the gears.
SELF-CENTERING
All of our gears are self-centered providing very low axial and
radial run-out.
Main characteristics
of our HIRTH couplings:
Standard hirth
couplings 50 - 1200 mm in diameter
Special hirth
couplings up to 1500 mm in diameter
Diameter quality
up to ISO 4
Indexing precision
±1"
Pair height
of hirth coupling set up to ±0.01 mm
Parallelism
error of pair measured at 6 points less than 0.01 mm at worst
point on diameters up to 710 mm
Design & calculation
guide:
Because
of the inclination of the tooth faces, an axial force Fa must
be applied, due to the peripheral force Fu of the driving
torque M. This axial force is:
This axial force must
be absorbed with a safety coefficient of v = 1,8 to 3, due
to outside systems which tend to compress the couplings.
Pressure calculation:
In a compression
situation, with a suitable Fva load and with no transmission
of force, this load is equally distributed on both faces on
the tooth. Therefore, there is no resulting bending stress.
But when transmitting torque M, pressure rises on one face
of the tooth and diminishes on the other. The maximum pressure
is calculated as follows:
