GEAR
Process
Novexa's on-site refurbishing process matches very specific criteria. Our unique approach guarantees a quick intervention (which reduces production losses considerably) at relatively low costs (about 7 to 10% of new price). At the same time, our approach helps to increase the shelf life of gear (8 to 12 years on average before a possible new intervention).
What makes us stand out
An insufficient knowledge of gear and an untailored intervention lead only to short-term solutions and are unsatisfactory.
- Lapping solutions are no mechanic solutions and the resulting wear reduces equipment shelf life considerably
- Our activity cannot be compared to a teeth grinding process carried out by some companies (lubricant distributor or maintenance companies)
- In opposition to the common idea, the flapping of a crown does not entail a higher shelf life than a reprofiling process (the average shelf life of the other side of the crown is about 50% of the first one)
- Finally, we draw attention to the wear rate, which determines the duration of life after intervention (use of Novexa template)
Actually, the unique device, established by Novexa, is fruit of 15 years of reprofiling experience, an exclusive method to which we are strongly committed.
Our intervention method
Novexa is an expert in on-site gear involute profile recutting sur site des engrenages, without dismantling of the facility. Based on our audit reports we correct different defects.
We assure the complete coordination of the site, integrating gear machining :
- Pinion profile control (pitch, profile, flatness)
- Crown machining with guaranteed cutting
- 3000 points of control on average during and after reprofiling process
- Cutting control with the client
- Advice on casing and type of lubrication
As well as on guidance elements :
- Level measurement and lineage of rotative equipment
- Pinion shaft alignment with laser equipment
- Innovative scrapping solution : bearings on pinions and mill trunnion bearings
- Backlash control and relief of pinion bearings (or bearing clearance)
A reprofiling intervention can be considered on all types of gear teeth.
Straight or helical gear teeth.
CHEVRON gear teeth.
The complete analysis of the kinematic chain is necessary if vibration levels are excessive.
A preliminary control of the geometry can be necessary if alignment levels need to be defined.
A reprofiling measure is no guaranteed remedy for the treatment of all vibration problems.
A reprofiling measure offers you a restoring of your profiles corresponding to the profiles of a new crown !
The reprofiling process is carried out manually with hand-held machinery.
15 years of experience enabled us to form professional and experienced teams.
A poorly machined tooth and the meshing process will produce shocks.
Before and after a reprofiling process, maximum tolerance levels respected by NOVEX are as follows :
Profiles : 0.10 mm on mill, 0.15 mm on kiln
Pitch : 0.10 mm on mill, 0.20 mm on kiln
Planarity : 0.10 mm
Cutting tolerance levels are often included in 0,07 mm on 70% of the load-bearing surface.
The crown is recut with approximately 3000 control points.
Only the template 1 tooth is shown on these pictures. Other tools are used in order to confirm the accuracy of the cutting sides.
Nevertheless, a new pinion should be used in order to match the load distribution.
Before and after reprofiling.
The control of the pitch and the regularity of the machining are necessary to maintain a constant pressure angle at 20° on every transfer of loads (2/1/2 teeth).
Every tooth is numbered.
A listing table of all the teeth is handed over after the intervention.
An analysis of the geometry is systematic
- Out-of-true / out-of-round control
- Control and adjustment of tooth thickness backlash and operating center distance backlash
- Fissure control on every tooth.
Load distribution control is an essential step after reprofiling.
The out-of-true can be corrected thanks to left / right alteration depending on the observed load distribution.
The surface of contact must be of 80% before honing.
A shimming of the pinion is supervised by NOVEXA.
The use of a honing lubricant is part of the procedures and guarantees supplied by NOVEXA.
The machining by NOVEXA shows defects of 0,1 mm which shows that honing is important in order to avoid :
- areas of high pressure
- the occurrence of pittings, chipping and excessive vibration levels
Sometimes, a retouching of some adjoining elements is necessary as :
- gear teeth on coupling
- scrapping of pinion bearings
- control of the oil pick-up ring
A shaft control (oil pick-up ring on a free standing bearing) is necessary
- control of backlash shaft / bearings
- measurement of oil entry relief
- scrapping if necessary
- blue print control
Visionée : Etape 1
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Novexa assures the resetting of gear and durably solves the following problems :
- High vibration levels
- Tooth breakages or beginning and / or progressive fissures
- Bad load distribution
- Shocks on meshing gear or on the level of a crown junction
- Hot or cold scuffing
Novexa intervenes on all types of teeth
On gear, we intervene directly on-site and on all types of teeth :
- Cemented, rectified quenched or heart quenched
- All types concerning width and diameter
- Module superior to 10
- Types of teeth : straight, helical, chevron and conical
Our tolerance levels for cutting are very low and guarantee therefore a perfect and durable result :
- Distortion of teeth (profile and pitch) inferior to 0.15mm on kiln
- Distortion of teeth (profile and pitch) inferior to 0.10mm on mill
- Teeth flatness inferior to 0.15mm
- Minimal distribution of loads representing 70% * width* height
We dispose of specific equipment and numerous exclusive tools, developed in collaboration with our research department :
- Resetting of profiles according to templates developed on our gear software
- Control material for exterior diameters
- Laser and theodolite lineage
- Control equipment for geometrical (out-of-true / out-of-round , adjustment of pinion / crown)
- Machining of the root radius in order to avoid cracks due to a weak area
A reduced length of intervention
Novexa guarantees the machining of a crown in 3 days on average (machining time can range from 2 to 5 days according to deformation levels and the number of daily staff available).
Our extremely short intervention times represent therefore an important source of cost-savings, as production losses linked to stoppages are avoided.
Guarantee – Novexa's commitment
Through a preliminary commitment regarding cutting, Novexa guarantees the geometric conformity of profiles and the quality of the distribution of loads before restarting of the machine.
After every on-site reprofiling intervention, a machining control is planned. Our two companies sign a record of proceedings concerning the end of the mission.
Novexa has always been an expert in managing wear speed. As a privileged partner in the industry, Novexa disposes of a long record of interventions regarding wear of gear, reprofiling, consulting and audit.
As of today, Novexa has developed its service range even further : our unique know-how applies to the wear of tires, alignment control measures and linked services ( bearing scrapping, welding repair etc.) as well.
GEAR