impact Crusher

Upper Frame: A welded structure made of Q355B steel plates (thickness 10–20 mm), forming the feeding and crushing chamber. It is equipped with a feeding hopper and impact plate adjustment devices, with reinforcing ribs (thickness 8–15 mm) to resist impact forces.

Lower Frame: A cast steel (ZG270-500) or welded steel structure supporting the rotor and motor. It is fixed on the foundation with anchor bolts and has a discharge port at the bottom, with a thickness of 15–30 mm to ensure stability.

Rotor Disk: A circular plate made of cast steel (ZG310-570) or forged steel, with a thickness of 20–50 mm. It is mounted on the main shaft and has evenly distributed holes for installing hammer shafts.

Impact Hammers: Key working parts made of high-chromium cast iron (Cr15–20) or alloy steel (40CrNiMo). They are hinged on the hammer shafts and can swing freely, with a weight of 2–20 kg depending on the model. The hammer head is designed with a sharp or blunt shape according to material characteristics.

Main Shaft: A forged alloy steel (40Cr) shaft with a diameter of 50–200 mm, connecting the rotor disk and motor. It is supported by spherical roller bearings at both ends to withstand radial and axial loads.

Hammer Shafts: Made of 40Cr steel, with a diameter slightly larger than the hammer eye to ensure flexible swing of the hammers.

Impact Plates: Wear-resistant plates made of high manganese steel (ZGMn13) or high-chromium cast iron, with a thickness of 20–40 mm. They are installed on the upper frame and form a crushing cavity with the rotor. The number of impact plates is 1–3, depending on the crushing stage (primary or secondary).

Adjustment Devices: Hydraulic cylinders or handwheels that adjust the gap between the impact plate and the rotor (5–50 mm) to control the discharge particle size. Each impact plate has an independent adjustment mechanism for flexible control.

Motor: A three-phase asynchronous motor (15–315 kW) providing power, connected to the main shaft via a V-belt or coupling. The motor speed is adjustable according to material hardness.

Pulley/Belt: A V-belt drive system with a large pulley on the main shaft and a small pulley on the motor, transmitting torque with a transmission ratio of 1:2–1:5.

Safety Guards: Protective covers installed on the rotor, pulley, and feeding port to prevent accidents during operation.

Dust Removal System: A fan and dust collector connected to the crushing chamber to reduce dust emissions, with a dust collection efficiency of ≥95%.

Lubrication System: Grease or thin oil lubrication for bearings, with automatic lubricators to ensure continuous lubrication.

Pattern Making: Sand or foam patterns are made according to the hammer shape, with a shrinkage allowance of 1.5–2.0%.

Molding: Resin-bonded sand molds are used, with the cavity coated with a refractory coating to improve surface quality.

Melting and Pouring:

Raw materials are melted in an induction furnace at 1450–1500°C, with chromium and other alloys added to achieve the chemical composition (C 2.8–3.5%, Cr 15–20%).

Molten iron is poured into the mold at 1400–1450°C, with a controlled pouring speed to avoid inclusions.

Heat Treatment: Solution annealing at 950–1000°C (air-cooled) followed by tempering at 250–300°C to improve hardness (HRC 55–65) and toughness.

Pattern and Molding: Wooden or metal patterns are used, and resin-bonded sand molds are made with cores for hammer shaft holes.

Pouring and Heat Treatment: Cast steel is melted at 1520–1560°C and poured into the mold. After casting, normalization at 880–920°C (air-cooled) and tempering at 600–650°C are performed to achieve hardness HB 180–220 and eliminate internal stress.

Billet Heating: Steel billets are heated to 1100–1150°C in a gas furnace to ensure plasticity.

Forging: Open-die forging is used to form the shaft shape, with upsetting and drawing processes to align the grain structure.

Heat Treatment: Quenching at 840–860°C (oil-cooled) and tempering at 500–550°C to achieve hardness HRC 28–32 and tensile strength ≥785 MPa.

Rough Machining: CNC lathe or milling machine processes the outer circle, end face, and hammer shaft holes, leaving a 1–2 mm machining allowance.

Precision Machining: Grinding the end face to flatness ≤0.1 mm/m and surface roughness Ra3.2 μm. Drilling and reaming the hammer shaft holes to ensure dimensional accuracy (H7 tolerance).

Turning: CNC lathe processes the outer circle, steps, and keyways, leaving a 0.3–0.5 mm grinding allowance.

Grinding: Grinding the journal surfaces to IT6 tolerance and surface roughness Ra0.8 μm, ensuring coaxiality ≤0.02 mm.

Cutting: High manganese steel or high-chromium cast iron plates are cut to size using plasma cutting or laser cutting.

Grinding: The working surface is ground to flatness ≤0.2 mm/m and surface roughness Ra6.3 μm, with edges deburred to avoid material blockage.

Welding and Stress Relief: Welded frames are annealed at 600–650°C to eliminate welding stress.

Milling and Drilling: CNC milling machine processes the mounting surfaces of impact plates and bearings, ensuring flatness ≤0.15 mm/m. Drilling and tapping the bolt holes (M16–M30) with thread tolerance 6H.

Material Testing:

Spectrometric analysis verifies the chemical composition of cast and forged parts (e.g., Cr content in impact hammers).

Tensile and impact tests check mechanical properties (e.g., impact energy of hammers ≥15 J/cm²).

Dimensional Inspection:

Coordinate measuring machine (CMM) inspects key dimensions such as rotor disk thickness, main shaft diameter, and impact plate flatness.

Gauges and dial indicators check the fit between the main shaft and bearings, ensuring clearance meets design requirements.

Non-Destructive Testing (NDT):

Magnetic particle testing (MPT) detects surface cracks in the main shaft, rotor disk, and impact hammers.

Ultrasonic testing (UT) inspects internal defects in cast rotor disks, with defects >φ3 mm rejected.

Performance Testing:

Dynamic Balancing: Rotor assembly is balanced to G6.3 grade (vibration ≤6.3 mm/s) to avoid excessive vibration during operation.

Empty Load Test: Running the equipment without load for 2 hours to check bearing temperature (≤70°C) and abnormal noise.

Load Test: Crushing standard materials (e.g., limestone) for 8 hours to verify production capacity, discharge particle size, and hammer wear.

Foundation Preparation: Concrete foundation (C30 grade) is poured with embedded anchor bolts, with levelness ≤0.1 mm/m. The foundation is cured for at least 28 days.

Lower Frame Installation: The lower frame is hoisted to the foundation, leveled with shims, and anchor bolts are tightened to 70% of the specified torque.

Rotor and Main Shaft Assembly: The main shaft is installed in the lower frame’s bearing seats, and the rotor disk is mounted on the shaft. Bearings are lubricated with grease (NLGI 2).

Impact Plate Installation: Impact plates are mounted on the upper frame, and the gap between impact plates and rotor is adjusted to the design value (5–50 mm) using hydraulic cylinders or handwheels.

Upper Frame and Feeding Hopper Mounting: The upper frame is bolted to the lower frame, and the feeding hopper is installed, ensuring alignment with the rotor.

Drive System Connection: The motor is placed on the motor base, and V-belts are installed with proper tension (deflection 10–15 mm under 100 N force).

Auxiliary Systems Installation: Dust removal pipes and lubrication lines are connected, and safety guards are installed.

Commissioning:

Empty run for 1 hour to check rotation direction and stability.

Load test with materials, adjusting the impact plate gap to achieve the required discharge particle size.

Check all systems for leaks, abnormal noise, or overheating, and make adjustments as needed.