Double toggle Jaw Crusher

Detailed Introduction to Double Pendulum Jaw Crushers

I. Composition and Structure

1. Key Structural Components

• Frame: Serves as the supporting framework, bearing all loads during crushing. It is typically made of gray cast iron (HT250) or welded steel structures (Q355B), available in integral or modular designs (for easier transportation and installation).

• Fixed Jaw: Secured to the front wall of the frame, its surface is fitted with a fixed jaw plate (made of wear-resistant materials such as ZGMn13 or high-chromium cast iron), forming a crushing chamber with the moving jaw.

• Moving Jaw: A core moving component connected to the eccentric shaft via bearings at the top and hinged to the toggle plate at the bottom. Its surface is equipped with a moving jaw plate (same material as the fixed jaw plate). The moving jaw follows an elliptical trajectory ("small swing at the top, large swing at the bottom"), combining extrusion and grinding actions.

• Eccentric Shaft: Forged from 40Cr or 42CrMo (forging ratio ≥3), it is driven by a motor via a pulley to rotate, acting as the core component that drives the moving jaw. Flywheels are mounted at both ends to balance inertia and reduce vibration.

• Toggle Plate: Connects the bottom of the moving jaw to the rear wall of the frame, transmitting crushing forces and serving as a safety device—breaking under excessive loads (e.g., uncrushable materials) to protect critical components. It is usually made of ZG35CrMo.

• Discharge Opening Adjustment Device: Adjusts the gap between the moving jaw and fixed jaw at the bottom by adding/removing shims or adjusting wedges, controlling the output particle size (typically 10–300 mm).

• Lubrication System: Includes grease nipples or centralized lubrication devices at the eccentric shaft bearings and suspension shaft bearings, using calcium-based grease (operating temperature ≤60°C) to ensure wear resistance and heat dissipation of moving parts.

2. Structural Features

II. Manufacturing Process

1. Frame Manufacturing

• Cast Frame: Sand casting (gray cast iron HT250) is used, with a melting temperature of 1400–1450°C. After casting, aging treatment (200–250°C for 24 hours) is performed to eliminate internal stress. Critical parts (e.g., bearing seats) undergo annealing (600–650°C) to control hardness at HB180–220.

• Welded Frame: Q355B steel plates are cut, beveled, and welded (using E5015 electrodes). After welding, vibratory aging or stress relief annealing (550–600°C) is conducted to prevent deformation. Non-destructive testing (UT, level II qualification) is performed post-welding.

2. Eccentric Shaft Manufacturing

• Raw material: 40Cr round steel is forged (free forging) into blanks with a forging ratio ≥3 (to ensure grain refinement). After forging, normalizing (860–880°C air cooling) is performed to achieve a hardness of HB200–230.

• Machining: Rough turning is followed by quenching and tempering (840–860°C oil quenching + 580–600°C tempering) to reach HRC28–32. The eccentric section and journal are finish-turned to IT6 tolerance with a surface roughness of Ra ≤1.6 μm. Magnetic particle inspection (MT) is finally conducted to ensure no cracks.

3. Moving Jaw and Liner Manufacturing

• Moving Jaw Body: Made of ZG35CrMo, it undergoes annealing after casting to eliminate stress, followed by quenching and tempering (HRC25–30) after rough machining. Critical parts (e.g., bearing holes) are finish-bored to IT7 tolerance, with a fit clearance of 0.1–0.2 mm with the eccentric shaft.

• Liners: ZGMn13 high manganese steel (water toughened: heated to 1050–1100°C, held, and water-quenched to obtain austenitic structure with work-hardening properties) or high-chromium cast iron (Cr15–20, HRC60–65, suitable for hard rock crushing) is used. Liners are fixed to the jaw body via bolts or wedges with a 1–2 mm buffer gap.

4. Toggle Plate and Transmission Components

• Toggle Plate: Made of ZG35 or QT500-7, it undergoes stress relief annealing after casting. The contact surfaces at both ends are milled to a surface roughness of Ra ≤6.3 μm to ensure flexible articulation with the moving jaw and frame.

• Pulley and Flywheel: Cast from gray cast iron HT200, they undergo static balance testing (eccentricity ≤0.05 mm/kg) to ensure stable operation.

III. Quality Control Processes

1. Raw Material Inspection

• Steel plates, round steel, and other raw materials must provide material certificates (e.g., chemical composition and mechanical property reports). Sampling is conducted for spectral analysis (to ensure element content compliance) and tensile testing (to verify tensile strength and yield strength meet standards).

• Castings (frames, moving jaws, etc.) undergo visual inspection (no pores or shrinkage), ultrasonic testing (UT, internal defects ≤Φ3 mm), and hardness testing (e.g., HT250 hardness ≥HB180).

2. Processing Accuracy Control of Key Components

• Eccentric Shaft: Journal roundness error ≤0.01 mm, coaxiality error ≤0.02 mm/m, inspected using a coordinate measuring machine.

• Moving Jaw Bearing Hole: The fit clearance with the eccentric shaft is checked using feeler gauges to ensure it is within 0.1–0.2 mm; excessive clearance causes noise and wear.

• Crushing Chamber Dimensions: The parallelism error between the fixed jaw and moving jaw ≤0.5 mm/m (top and bottom), calibrated using a laser level to avoid uneven output particle size.

3. Assembly Quality Control

• Bearing Assembly: Heat fitting (heating bearings to 80–100°C) is used to avoid deformation from hard hammering. After assembly, the eccentric shaft should rotate by hand without jamming, with axial movement ≤0.3 mm.

• Toggle Plate Connection: Contact surfaces with the moving jaw and frame are coated with grease, and clearance is checked with feeler gauges to ensure ≤0.1 mm for uniform force distribution.

4. No-Load and Load Testing

• No-Load Test: 2-hour operation with bearing temperature rise ≤40°C (above ambient), no abnormal vibration (amplitude ≤0.1 mm), and noise ≤85 dB.

• Load Test: 4-hour crushing of medium-hard materials (e.g., limestone) with ≥90% output particle size compliance (per set discharge opening), uniform liner wear, and no local overheating.

IV. Main Applications in Production Lines and Industries

1. Role in Production Lines

• Further crushing pre-crushed materials (e.g., 100–300 mm) to 20–100 mm, providing qualified raw materials for subsequent cone crushing or sand making.

• Utilizing the complex trajectory of the moving jaw to 挤压，bend, and grind materials, improving crushing efficiency (15–30% higher than the simple pendulum type), suitable for crushing medium-hard materials (e.g., granite, iron ore).

2. Industry Applications

• Mining Industry: Used for medium and fine crushing of metal ores (iron, copper, gold) and non-metallic ores (limestone, quartz sand). For example, crushing pre-crushed iron ore (200–300 mm) to 50–100 mm for ball mill grinding.

• Construction Materials Industry: Crushing construction waste (concrete blocks, bricks) to produce recycled aggregates (5–30 mm); crushing limestone, gypsum, etc., for cement and lime production.

• Highway and Railway Construction: Crushing hard rocks (basalt, granite) to produce road base aggregates (10–30 mm) with uniform particle grading.

• Metallurgical Industry: Crushing coke, iron ore, and other raw materials to provide qualified materials for blast furnace smelting.

• Chemical Industry: Crushing phosphate rock, pyrite, etc., for fertilizer and chemical raw material processing.