Cone Crusher head ball

Axial Load Support: Bearing the vertical loads generated during crushing (up to tens of thousands of kilonewtons) and transferring them to the upper frame or adjusting ring, ensuring the moving cone maintains its vertical position.

Rotational Guidance: Acting as a pivot point for the moving cone’s eccentric rotation, allowing smooth oscillation (amplitude 5–20 mm) while minimizing lateral displacement.

Wear Reduction: Providing a hardened, low-friction surface that interfaces with the upper bearing or socket, reducing abrasion caused by continuous movement.

Alignment Maintenance: Ensuring the moving cone remains concentric with the concave (fixed cone), preserving the crushing gap accuracy and preventing uneven wear on both components.

Ball Head: A hemispherical or spherical tip with a radius ranging from 50 mm to 300 mm, depending on the crusher size. It is made of high-carbon chromium bearing steel (e.g., GCr15) or alloy steel (42CrMo) with a hardened surface (HRC 58–62).

Shaft Neck: A cylindrical or tapered section that connects the ball head to the moving cone body, with a diameter 1.5–2 times the ball head radius. It is often forged as a single piece with the ball head for structural integrity.

Transition Fillet: A rounded corner (radius 10–30 mm) between the ball head and shaft neck, designed to reduce stress concentration and prevent fatigue cracking under cyclic loads.

Lubrication Groove: A circumferential groove near the base of the ball head that retains lubricant (grease or oil), ensuring a continuous film between the head ball and upper bearing. The groove is 2–5 mm deep and 5–10 mm wide.

Mounting Threads/Keyway: Optional features on the shaft neck for securing the head ball to the moving cone, with threads (class 6g) or keyways (ISO 4156) facilitating torque transmission.

Hardened Layer: A 2–5 mm deep case-hardened layer on the ball head surface, achieved via carburizing or induction hardening, to balance wear resistance (surface HRC 58–62) with core toughness (HRC 25–35).

Material Selection: High-carbon chromium bearing steel (GCr15) is preferred for its excellent wear resistance and fatigue life. Chemical composition: C 0.95–1.05%, Cr 1.3–1.65%, Mn ≤0.4%, Si ≤0.35%.

Billet Preparation: Steel billets are cut to weight (10–50 kg) and heated to 1100–1200°C in a continuous furnace, ensuring uniform temperature distribution.

Upsetting and Forming: The heated billet is upset to reduce height and increase diameter, then forged into a preform with a rough spherical shape using closed-die forging. This process refines the grain structure and aligns metal flow with the component’s stress direction.

Finishing Forging: The preform is reheated to 1050–1100°C and forged to the final shape, with the ball head and shaft neck formed in a single operation to ensure dimensional accuracy (±1 mm).

Material Selection: Alloy cast steel (ZG42CrMo) is used, with tensile strength ≥600 MPa and impact toughness ≥30 J/cm².

Investment Casting: For complex geometries, wax patterns are used to create ceramic molds. Molten steel (1520–1560°C) is poured into the molds, producing near-net-shape components with minimal machining required.

The forged or cast blank is mounted on a CNC lathe to machine the shaft neck, transition fillet, and preliminary ball head shape, leaving 1–2 mm finishing allowance.

Quenching and Tempering: For GCr15, the blank is heated to 830–860°C, quenched in oil, then tempered at 150–200°C to achieve core hardness HRC 25–35.

Surface Hardening: The ball head is induction-hardened (frequency 10–50 kHz) to heat the surface to 850–900°C, followed by water quenching, resulting in a hardened layer (2–5 mm deep) with HRC 58–62.

Ball Head Grinding: A CNC spherical grinder machines the ball head to achieve a surface roughness of Ra0.1–0.4 μm and spherical tolerance (≤0.01 mm), ensuring proper fit with the upper bearing.

Shaft Neck Finishing: The shaft neck is ground to cylindrical tolerance IT6, with surface roughness Ra0.8 μm, facilitating secure mounting to the moving cone.

Groove Machining: The lubrication groove is milled or turned into the shaft neck, with precise depth and width to optimize lubricant retention.

The ball head surface is polished to reduce friction, and the non-hardened areas are coated with anti-rust oil or paint to prevent corrosion.

Material Testing:

Chemical composition analysis (spectrometry) verifies compliance with GCr15 or ZG42CrMo standards.

Metallographic examination checks for grain size (≤6 ASTM) and carbide distribution in the hardened layer.

Dimensional Accuracy Checks:

A coordinate measuring machine (CMM) inspects the ball head’s spherical radius, shaft neck diameter, and transition fillet, ensuring tolerances are within ±0.01 mm for critical features.

A roundness tester verifies the shaft neck’s cylindricity (≤0.005 mm) and the ball head’s sphericity (≤0.01 mm).

Mechanical Property Testing:

Hardness testing (Rockwell) confirms surface hardness (HRC 58–62) and core hardness (HRC 25–35).

Compression testing on samples ensures a compressive strength ≥2000 MPa, with no plastic deformation under 150% of rated load.

Non-Destructive Testing (NDT):

Ultrasonic testing (UT) detects internal defects in the forging, with any cracks or inclusions >φ1 mm rejected.

Magnetic particle testing (MPT) inspects the transition fillet and ball head surface for micro-cracks, with linear defects >0.2 mm resulting in rejection.

Performance Validation:

Wear Testing: A pin-on-disk test simulates contact with the upper bearing, requiring weight loss ≤0.1 mg after 10⁴ cycles.

Fatigue Testing: The component undergoes cyclic loading (10⁶ cycles) at 80% of yield strength, with no visible cracking or deformation.