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[China]
Trade Verify
Address: No.2-A-609, NO.1 Longyu Road, Jianxi District, Luoyang, Henan, China
Contact name:David
Luoyang Zhongtai Industrial Co., Ltd. |
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Verified Suppliers
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We provide girth gears in three different designs
1. Fabricated steel
- forged ring
- rolled plate
Cast steel
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.
Avantages of fabricated girth gears
1. The forged material structure excludes the risk of inclusions
2. Structure defects like gas holes, micro shrinkage, pin holes, hot tears, sand and slag inclusions are avoided
3. Hence, repair welding of the body structure and e.g. grinding of toothed areas is not required.
4. The fabricated manufacturing procedure excludes the need for patterns and risers
5. Rim material has higher hardness and higher strength than the material used for the underlying structure (i.e. web, gussets)
Features
1. External teeth
Maximum diameter: 16000 mm
Toothed face width: 1700 mm
Maximum module: 45 by hob
Maximum module: 65 gear finishing cutter
2. Internal teeth
Maximum Diameter: 6500 mm
Maximum module: 25.4
Toothed face width: 400 mm
Forging material process
Forging
Final rolling
Furnace cooling
Control on production
Water quenching
Hardness testing
Rough machining
Ultrasonic testing and dimensional inspection
Final inspection certification
Standards/Certificates
UNI EN ISO
AWS
ASTM
ASME
DIN
Applications
Our girth gears are applied in the cement and minerals industries:
Various types of horizontal mills
Rotary dryers
Rotary kilns
Any other large gear ring application
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
Item | Structural features | Processing measure | Test content |
Girth Gear | (1)GS42CrMo4Alloy Steel (corporate proprietary standards) HB 220~240 (2)semi-structured, Y-Spoke | (1) outer steel refining (R-H argon and vacuum treatment) (4)rough hobbing, release time, repair the joint surface, then fine
roll | (1)castings mechanical properties and chemical composition
(internal standard) |
The technical requirements of a large CITICIC Gear ring:
1) is pretreated before normalizing surface hardening treatment,
the hardness should HB210 ~ 250; mechanical performance are the
ultimate strength Rb 690MPa, yield stress Rs 490MPa, elongation D5
11%, reduction of area W 25% , impact toughness Ak 30J; teeth
induction hardened, hardness HRC50 ~ 55; effective hardened layer
depth 3 ~ 5mm.
2) overall ultrasonic flaw detection, internal quality should meet
two requirements GB7233-87 standard requirements; tooth and fillet
magnetic particle inspection, quality should meet two requirements
GB/T9444-88 standards.
3) Note the casting is not rounded R5 ~ R10.
4) Tooth chamfer at both ends and 1 45b.5) by two and a half ring
gear tooth width of each ring coupling along the edge of a whole
ring made with high strength bolts, combined with the tooth surface
must be at the bottom center.
2 large ring gear manufacturing process
2.1 of rough
Steel casting blank is provided by CITIC Heavy Machinery Co., Ltd.
Heavy Forging plant, run by GB11352-89 standard specifies
requirements for modeling according to the casting process,
smelting, casting, hit boxes, cleaning, dressing castings;. During
inspection and acceptance by the drawings and Technical
requirements for steel blank
Checks, according JB/T6402-92 standards issued after acceptance
Down procedure.
2.2 roughing
Crossed by drawing and stay out allowance, alignment, connection,
processing both inside and outside the circle, combining face
milling, drilling and other processes.
2.3 Exploration injury
Overall ultrasonic flaw detection, internal quality should meet the
two requirements of GB7233-87 standards.
2.4 normalizing pretreatment
Semi-ring pairs normalizing and tempering treatment, provide a good
organization for subsequent surface hardening; press drawings
deformation of the half ring gear inspection after heat treatment.
2.5 Machining
First two and a half ring is made with high strength bolts
connecting the ring as a whole, the overall process by drawing a
circle Quannei Wai teeth and upper and lower end, and then drawing
and machining milling process requirements.
2.6 Elimination of processing stress
The overall ring annealed to eliminate stress.
2.7 overall ring surface hardening
IF along the alveolar tooth surface induction hardening, hardness
HRC50 ~ 55, effective hardened layer depth 3 ~ 5mm.
2.8 Final inspection
First, the detection frequency quenching, the hardness after
tempering ring gear cogging meets the requirements of the drawings;
secondly, to detect whether the maximum outer diameter larger size
D6944 as the deformation 3mm, the mechanical correction required
until qualified; Thirdly, tooth and fillet magnetic particle
inspection, quality should meet two requirements GB/T9444-88
standard requirements; Finally, according to the drawings and
technical requirements for final inspection.
| No. | process | program of tests | inspection equipment | ||
1 |
| 1. Material: high quality cast steel 2. Formulate reasonable casting process and ensure casting quality by means of computer simulation of solidification 3. Formulate reasonable smelting process to ensure the chemical composition of casting 4. Formulate reasonable heat treatment process to ensure Verify the mechanical properties of the casting
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2 |
| 1. Strictly control the quality of type (core) sand, ensure the strength and control of water 2. Sand tamping, inclined surface polishing, paint brush twice 3. Place the pouring riser and cold iron according to the process requirements 4. Clean and bake as required cavity
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Check the quality of type (core) sand and surface sand 2. Check the cavity size Check the baking time
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3 |
Smelting casting | 1. Choose low S.P pig iron, select scrap steel, auxiliary materials and alloy of baking furnace according to process 2. According to special process smelting, make steel S.P hazardous elements meet internal control standards 3. The finished molten steel is treated with argon blowing in the ladle and R-H vacuum circulation degassing to make the molten steel composition uniform, harmful oxygen (H, O) reduction, uniform temperature, increase the fluidity of molten steel, so as to ensure good liquid replenishing of the casting and prevent the casting from porosity and other defects Strictly control casting temperature and casting speed according to the provisions |
50 t furnace R-h vacuum circulation degassing equipment for ladle argon blowing device
| 1. Furnace materials must meet the technological requirements 2. Control feeding temperature, feeding quantity, pure boiling time, steel temperature 3. The direct reading spectrometer is used to quickly detect the chemical composition in front of the furnace to ensure that the equipment is in the best state during melting and the chemical composition of the finished product meets the requirements during pouring 4. Check the parameters of argon blowing and R-H vacuum treatment 5. Check the starting temperature and Pouring time
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Direct reading spectrometer The physical and chemical equipment
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4 |
Cleaning and heat treatment | 1. The internal heat preservation time of casting mold shall not be less than the process requirements 2. Sand falling, shot blasting, cutting and pouring risers meet the technological requirements 3. Strictly carry out the blank heat treatment To ensure the uniformity of furnace temperature and refine the original structure of casting
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50t Inert falling sand machine and 8.5 ×12m Heat treatment furnace
| 1. Check the furnace temperature record 2. The sample is heat-treated with the casting in the same furnace, and the mechanical properties are sent to be checked immediately 3. Check the surface quality of the blank Quantity, geometric dimension and machining allowance
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The physical and chemical equipment |
5 | rough machining | 1. Reserve allowance for rough machining according to technological provisions Artificial aging treatment
| Vertical lathe 8.5 ×12m Heat treatment furnace
| Check the size Visual inspection for defects ultrasonic inspection
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