Tractor Part Cold Draw Seamless Tube

1. Product definition and core features

Cold-drawn seamless pipe is the basic material for manufacturing key parts of tractors. It is made by secondary processing of hot-rolled seamless pipe at room temperature through **cold drawing process (Cold Drawing)**. Compared with ordinary steel pipes, it has the following outstanding characteristics:

High dimensional accuracy: outer diameter tolerance±0.1mm, wall thickness deviation≤5%

Excellent surface quality: roughness Ra≤0.8μm (equivalent to mirror turning effect)

Strong mechanical properties: tensile strength increased by 15-20%, yield strength increased by 10-15%

2. Production process flow

mermaid

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graph TD

A[hot-rolled tube billet] --> B[pickling and rust removal]

B --> C[phosphorus saponification treatment]

C --> D[multi-pass cold drawing]

D --> E[finishing and straightening]

E --> F[non-destructive testing]

F --> G [Finished product heat treatment]

Key process control points

Cold drawing deformation: single-pass cross-sectional shrinkage is controlled at 15-30% (to avoid excessive work hardening)

Mold design: tungsten carbide drawing dies (lifespan up to 5000 times/set)

Lubrication system: high-pressure saponified liquid injection (pressure 8-12MPa)

3. Typical application parts of tractors

Component name Material brand Specification range Special requirements

Hydraulic cylinder pipe 27MnB5Φ32-120×4-10mm Internal honing Ra≤0.4μm

Transmission shaft pipe 34CrMo4Φ50-150×5-12mm Hardened layer depth≥3mm

Suspension link Q355BΦ25-80×3-8mm Straightness≤0.5mm/m

PTO sleeve 42CrMoΦ60-180×6-15mm Ultrasonic flaw detection grade A

4. Material performance comparison

Performance index Hot rolled pipe Cold drawn tube Improvement

Dimensional accuracy IT12-13 IT9-10 Improved by 3 levels

Surface hardness 180-220HB 220-260HB +20%

Fatigue life 10^5 times 10^6 times 10 times

Grain size 5-6 levels 8-9 levels Refined by 2 levels

5. Special treatment technology

(1) Inner surface strengthening

Rolling process: Create a 0.1-0.2mm compressive stress layer on the surface

Chromium plating: Hard chrome layer thickness 20-50μm (HV≥800)

(2) Anti-corrosion solution

Phosphating: Zinc phosphating film weight 2-4g/m²

Dacromet coating: Salt spray resistance≥500h

(3) Intelligent detection

Eddy current flaw detection: Can detect defects aboveΦ0.3mm

Laser diameter measurement: Online detection accuracy±0.02mm