HB210～250 Mill Girth Gear High Strength Hardness High Resistance Alloy Steel

Product Specification

HB210～250 Mill Girth Gear High Strength High Hardness High Resistance Alloy Steel

1.Basic introduction to Girth Gears
Girth Gears offered find extensive application in different industry sectors including in sponge iron plants, steel & cement industry, mining industry, wind mills as well as in other industry sectors. These are made available in module range of 10 Module to 70 Module and in minimum diameters of 100 mm to 15000 mm. Further, these comprise maximum weight of 70 MT single pieces. Here the range of hardened & ground gear boxes/gears comprise Worm gear boxes, Helical / Double helical gears/gearboxes, Helical-Bevel gearboxes, Planetary Gearboxes and others.With more than 1000 girth gears sold over the world CITICIC Gear is a leading supplier in the cement and mineral industry.

2.ZTIC Gear Cutting Machines include
Ø16m CNC Hobbing Machine
Ø12m Gear Cutting Machine (Switzerland)
Ø10m Hobbing Machine (Germany)
Ø4m CNC High Speed Hobbing Machine (Germany)
Ø1.6m Horizontal CHC Hobbing Machine (Germany)
Ø5m CNC Profile Gear Grinding Machine (Germany)
Ø2.8m CNC Profile Gear Grinding Machine (Germany)
Ø1.25m CNC Profile Gear Grinding Machine (Germany)
Ø1m CNC Profile Gear Grinding Machine (Germany)
Ø0.8m CNC Profile Gear Grinding Machine (Germany)

3.Basic components of Girth Gears
(1) Ductile (Nodular) cast iron
Fabricated gears became more common in the past and are constructed with forged steel gear rim materials and electro welded body structure. The rings are manufactured from a whole block of high resistance alloy steel. After the rough machining of the ring, we carry out hardening and tempering heat treatment in order to improve the mechanical characteristic and therefore its relevant performance.
(2) Avantages of fabricated girth gears
The forged material structure excludes the risk of inclusions and avoids structural defects such as porosity, micro-shrinkage, pinholes, thermal cracks, sand and slag inclusions. As a result, there is no need for restorative welding of the main structure, grinding of the tooth area, etc. The manufacturing procedure excludes the need for patterns and risers. The rim material has higher hardness and strength than the material used for the underlying structure (i.e. webs, cleats). These features will reduce delivery times and costs. Process manufacturing ensures fast delivery.

(3) External teeth
Maximum diameter: 16000 mm
Toothed face width: 1700 mm
Maximum module: 45 by hob
Maximum module: 65 gear finishing cutter
(4) Internal teeth
Maximum Diameter: 6500 mm
Maximum module: 25.4
Toothed face width: 400 mm
(5) Pinions
ZTIC Gear invested in significant resources and achieved many innovations with pinions. The right combination of material, hardness and finishing between pinion and gear is crucial for a long lifetime of the installed equipment. We design and manufacture pinions to match every customers need, no matter how unique the situation might be.

4.Quality assurance documents
The following reports are to be submitted to Quality Assurance:
a. Chemistry report
b. Physical report
c. Heat treatment documents
CITIC HMC Q/HM 973.2-2007 Specification for Steel Castings for Grinding Mills
d. Ultrasonic inspection report (before and after repairs)
e. Magnetic particle inspection report (before and after repairs)
f. Dimensional report
g. Weld repair maps
h. Weld procedures and Procedure qualification record
i. Welder qualification
j. Nondestructive testing inspector qualification

5. Mill Girth Gear Technical parameters 

6. Mill Girth Gear photo explanation