Cone Crusher Main Shaft

Power Transmission: Transmitting torque from the eccentric bushing to the moving cone, driving its eccentric rotation to generate crushing forces.

Load Bearing: Bearing axial and radial loads from the moving cone and crushing process (up to thousands of kilonewtons), transferring these forces to the frame’s bearings.

Eccentric Motion Guidance: Working with the eccentric bushing to maintain the moving cone’s orbital path, ensuring stable crushing gap control and uniform material processing.

Structural Alignment: Maintaining the concentricity between the moving cone and fixed cone, critical for consistent product size and reduced wear on liners.

Shaft Body: A one-piece forged structure made of high-strength alloy steel (e.g., 42CrMo or 35CrNiMo) with a diameter ranging from 100 mm to 500 mm. Its length varies by crusher size, typically 500–2000 mm.

Upper Cone Mount: A tapered or threaded section at the top for attaching the moving cone, with a precision-machined surface (tolerance IT6) to ensure concentricity.

Eccentric Bushing Interface: A cylindrical middle section with a polished surface (Ra0.8 μm) that fits into the eccentric bushing, often with oil grooves for lubrication.

Bearing Journals: Two or more cylindrical sections (upper and lower) that mate with the frame’s bearings, featuring tight dimensional tolerances (IT5–IT6) and surface roughness (Ra0.4 μm) to minimize friction.

Shoulders and Keyways: Radial shoulders that limit axial movement of bearings or bushings, and keyways for torque transmission between the shaft and moving cone.

Lubrication Channels: Axial and radial drilled holes that deliver lubricant to bearing journals and the eccentric bushing interface, preventing overheating and wear.

High-strength alloy steel (42CrMo) is preferred for its excellent tensile strength (≥1080 MPa), yield strength (≥930 MPa), and impact toughness (≥60 J/cm²), suitable for dynamic load applications.

Billet Heating: The steel billet is heated to 1100–1200°C in a gas furnace, ensuring uniform temperature distribution to improve plasticity.

Open-Die Forging: The billet is forged into a rough stepped shape using hydraulic presses (1000–5000 tons), with multiple passes to refine the grain structure and eliminate internal defects. Key steps include upsetting (to increase diameter) and drawing (to extend length).

Precision Forging: The rough forging is shaped into the final stepped profile with near-net dimensions, reducing machining allowances to 5–10 mm.

Quenching and Tempering: The forged shaft is heated to 850–880°C, held for 2–4 hours, then quenched in oil to achieve a martensitic structure. Tempering at 550–600°C for 4–6 hours reduces brittleness, resulting in a hardness of HRC 28–35 and optimized toughness.

Local Surface Hardening: Bearing journals and keyways are induction-hardened to a depth of 2–5 mm, achieving HRC 50–55 to enhance wear resistance while maintaining core toughness.

The forged blank is mounted on a CNC lathe to machine all outer surfaces (diameters, shoulders, tapers), leaving 1–2 mm finishing allowance. Key dimensions (e.g., journal diameters) are controlled to ±0.1 mm.

Bearing Journals: Finish-turned and ground to achieve a dimensional tolerance of IT5 (e.g., φ200H5) and surface roughness Ra0.4 μm, ensuring proper fit with bearings and minimal friction.

Tapered Mount: The upper cone mount is finish-machined to a taper angle tolerance of ±0.05° and surface roughness Ra0.8 μm, ensuring concentricity with the moving cone.

Keyways and Oil Grooves: Milled using CNC machines with positional tolerance (±0.05 mm) and surface finish Ra3.2 μm, preventing stress concentration.

Axial and radial oil holes (φ5–φ15 mm) are drilled using CNC deep-hole drilling machines, with positional accuracy (±0.2 mm) to ensure unobstructed lubricant flow. Hole ends are deburred to avoid oil flow disruption.

The shaft undergoes dynamic balancing on a balancing machine at 500–1000 rpm, with residual unbalance limited to ≤5 g·mm/kg to reduce vibration and bearing wear.

Bearing journals are polished to Ra0.2 μm to reduce friction and improve bearing life.

Non-bearing surfaces are coated with anti-rust paint or zinc plating (5–8 μm) to resist corrosion during storage and operation.

Chemical composition analysis (spectrometry) confirms compliance with 42CrMo standards (C 0.38–0.45%, Cr 0.9–1.2%, Mo 0.15–0.25%).

Forging quality is inspected via ultrasonic testing (UT) to detect internal defects (e.g., cracks, inclusions) with size limits ≤φ2 mm.

A coordinate measuring machine (CMM) verifies all critical dimensions: journal diameters, taper angles, keyway positions, and oil hole locations.

Roundness and straightness of the shaft are measured using a laser alignment tool, with tolerance ≤0.01 mm/m.

Hardness testing (Rockwell) ensures bearing journals have HRC 50–55 and the core has HRC 28–35.

Tensile testing on forged samples confirms tensile strength ≥1080 MPa and elongation ≥12%.

Magnetic particle testing (MPT) detects surface cracks in keyways, shoulders, and journals, with any defect >0.2 mm in length rejected.

Eddy current testing checks for subsurface defects in hardened journal surfaces.

Rotational testing: The shaft is mounted in a test fixture and rotated at maximum speed (1500 rpm) for 2 hours, with vibration monitored to ensure levels ≤0.1 mm/s.

Load testing: A simulated axial load (120% of rated load) is applied for 1 hour, with post-test inspection showing no deformation (e.g., journal roundness change ≤0.005 mm).