Single swing Jaw Crusher

Detailed Introduction to Single Pendulum Jaw Crushers

The single pendulum jaw crusher is the most traditional and widely used type of jaw crusher. Its moving jaw swings in a single arc around a suspension shaft (similar to a pendulum), hence the name "single pendulum." Characterized by a simple structure, low cost, and easy maintenance, it plays a key role in primary crushing for small to medium-sized mines, construction materials, and road construction. It can crush materials with compressive strength ≤250 MPa (e.g., limestone, sandstone, gangue) with a crushing ratio of 3–5 and a discharge opening adjustable from 10–200 mm.

I. Composition and Structure of Single Pendulum Jaw Crushers

1. Frame

• As the load-bearing base, small to medium-sized models (e.g., PE250×400) use integral cast steel (ZG230-450), while larger models (e.g., PE600×900) adopt welded structures (Q235B steel plates, 15–30 mm thick). The frame features bearing seat holes (supporting the eccentric shaft) and toggle plate seats (mounting toggle plates) on both sides.

• The bottom is open (facilitating discharge), with the fixed jaw and transmission system fixed at the front and rear ends, respectively. The overall rigidity must withstand impact forces during crushing (100–500 kN, depending on the model).

2. Crushing Mechanism

• Fixed Jaw: Vertically or slightly inclined (≤15°) at the front of the frame, its surface is fitted with a fixed jaw plate (ZGMn13 high manganese steel, 30–80 mm thick) with trapezoidal or triangular teeth (5–10 mm high) to enhance material gripping.

• Moving Jaw: Connected to the frame via a suspension shaft (fixed fulcrum) at the top and linked to the toggle plate at the bottom, forming a "pendulum" structure. Made of cast steel (ZG310-570) with a moving jaw plate (symmetric to the fixed jaw plate), it swings in an arc around the suspension shaft during operation, creating periodic compression with the fixed jaw.

3. Transmission System

• Motor: Provides power (3–75 kW, model-dependent), connected to the pulley via V-belts with a rotational speed of 750–1500 r/min.

• Pulley & Eccentric Shaft: The pulley (HT250 gray cast iron) transfers motor power to the eccentric shaft (45# steel or 40Cr, tempered to 22–28 HRC). The eccentric design converts rotational motion into the moving jaw’s swing (150–300 cycles/min).

• Suspension Shaft & Bearings: The suspension shaft (45# steel, surface-hardened to 40–45 HRC) is fixed to the frame’s upper part, with the moving jaw swinging around it via sliding or rolling bearings. The eccentric shaft is supported by spherical roller bearings in the frame’s bearing seats for stable rotation.

4. Adjustment Device

• Uses shim adjustment: A set of shims of varying thicknesses is placed between the toggle plate and the frame’s rear wall. The discharge opening is adjusted by adding/removing shims with ±1 mm precision. Small to medium models require manual shim replacement, while large models may use manual jacks for easier adjustment.

5. Safety Device

• The toggle plate acts as a "safety pin": Made of HT200 cast iron (brittle material), it is installed between the moving jaw and frame’s toggle plate seat. When uncrushable materials (e.g., iron blocks) enter the chamber, the toggle plate fractures under excessive pressure, 切断动力传递 and protecting critical components (eccentric shaft, frame).

II. Manufacturing Processes

1. Frame Manufacturing

• Cast Frame: ZG230-450 molten steel is cast into blanks via resin sand molding (pouring temperature 1450–1550℃). After slow cooling (to avoid shrinkage/cracks), rough machining is followed by aging (relieving casting stress). The fixed jaw mounting surface is finish-machined to flatness ≤0.2 mm/m, and bearing seat holes are bored to H8 tolerance (Ra ≤3.2 μm).

• Welded Frame: Q235B plates are CNC-cut (±1 mm tolerance) and welded via submerged arc welding (weld height 8–12 mm). Post-welding vibratory aging (20–50 Hz for 2–4 hours) ensures residual stress ≤80 MPa to prevent in-service deformation.

2. Key Component Manufacturing

• Eccentric Shaft: 40Cr steel is forged (forging ratio ≥2.5), rough-turned, and tempered (840℃ quenching + 560℃ tempering) to 22–28 HRC. Precision turning ensures ±0.1 mm eccentricity tolerance, with the journal surface ground to Ra ≤1.6 μm. Magnetic particle inspection (MT) ensures no surface cracks.

• Moving & Fixed Jaws: The moving jaw is cast from ZG310-570 via sand molding, annealed (600–650℃ for 3 hours) after rough machining. The suspension shaft hole is bored to H7 tolerance with a 0.05–0.1 mm fit gap with the suspension shaft. The fixed jaw is either cast integrally with the frame or bolted, with parallelism to the moving jaw ≤0.2 mm/m.

• Jaw Plates: ZGMn13 undergoes water toughening (1050℃ for 1–2 hours, water-quenched) to form austenitic structure (impact toughness ≥180 J/cm²). Tooth profiles are formed via machining or casting for uniform material contact.

3. Assembly and Commissioning

• Assembly: The suspension shaft is fixed to the frame, followed by the moving jaw (with 0.1–0.2 mm bearing clearance), eccentric shaft, pulley, toggle plate, and shims. Bolts are torqued to specifications (e.g., M20 bolts: 200–250 N·m).

• No-Load Testing: 1-hour runtime checks bearing temperature (≤75℃), noise (≤90 dB), and smooth swinging. V-belt tension is adjusted (deflection 1.5% of span).

• Load Testing: 2-hour limestone crushing verifies discharge size compliance (≥90%), motor current stability (fluctuation ≤10%), and safety device functionality (toggle plate fractures under simulated overload).

III. Quality Control Processes

1. Raw Material and Blank Inspection

• Cast steel components (frame, moving jaw) undergo 100% visual inspection (no shrinkage/cracks) and 抽样 UT (internal defects ≤φ3 mm). Steel plates (welded frames) require material certificates with tensile strength ≥375 MPa.

• Forgings (eccentric shaft, suspension shaft) are verified for forging ratio and grain size, with sampled mechanical testing (tensile strength ≥600 MPa, yield strength ≥350 MPa).

2. Machining Accuracy Inspection

• Bearing seat hole coaxiality is checked with dial indicators (≤0.1 mm). Parallelism between fixed and moving jaw mounting surfaces is verified with levels (≤0.2 mm/m).

• Eccentric shaft eccentricity and roundness errors are measured with tool microscopes (≤0.1 mm), and journal surface roughness is validated with profilometers (Ra ≤1.6 μm).

3. Assembly and Performance Testing

• Assembly Gaps: The gap difference between the moving and fixed jaws (top vs. bottom) ≤1 mm. Toggle plate contact area with the seat ≥70% (ensuring uniform force transmission). Bearing temperature rise during no-load operation ≤40℃ (above ambient).

• Crushing Performance: Crushing 150 MPa limestone at rated capacity achieves a crushing ratio ≥90% of the design value (e.g., PE400×600: ≥3.8 vs. design 4). Oversize particle content ≤5%.

• Safety Validation: Simulated overload tests (1.5× rated feed size) confirm toggle plate fractures within 30 seconds without damaging other components.

IV. Applications in Production Lines and Industries

1. Small to Medium Mine Primary Crushing

• As the first-stage crusher in small iron ore or limestone mines, it reduces blasted ore (200–500 mm) to 50–150 mm for subsequent ball mills or cone crushers. For example, 100,000 t/year limestone mines often use PE400×600 models with vibrating screens for simple crushing lines.

2. Construction Materials Production

• Crushes sandstone and shale for wall materials (e.g., aerated concrete blocks) or construction waste (bricks, concrete) for recycled aggregates (roadbed backfill). Its simple structure suits frequent relocation (e.g., small mobile crushing stations).

3. Road Construction Base Crushing

• Crushes local cobblestones and rocks for ≤100 mm road base aggregates (e.g., cement-stabilized macadam) in rural or low-grade road projects. Screening can be omitted in low-requirement scenarios to reduce costs.

4. Coal Industry

• Crushes raw coal or gangue (compressive strength ≤80 MPa). Its low crushing ratio minimizes coal over-crushing (reducing fines loss), making it suitable for preprocessing in small to medium coal washeries.

V. Key Differences from Double Pendulum Jaw Crushers

• Motion Trajectory: The single pendulum moving jaw only swings in an arc (larger swing at the bottom), while the double pendulum moving jaw combines arc swing with vertical movement (higher efficiency).

• Efficiency: Single pendulum models have 10–20% lower capacity than same-size double pendulum models but offer simpler maintenance and lower costs.

• Material Suitability: Single pendulum crushers are better for medium-soft materials (e.g., limestone), while double pendulum models handle harder materials (e.g., granite).