Jaw Crusher Frames

Detailed Introduction to the Frame Component of Jaw Crushers

I. Composition and Structure of the Frame

1. Main Frame Structure

• Integral frame: Small/medium crushers (capacity ≤100 t/h) often use integral cast or welded structures, shaped like a "U" with vertical side walls (30–80 mm thick), a horizontal base plate (50–100 mm thick), and a top section connecting to the fixed jaw plate. A central bore for the eccentric shaft bearing housing is 预留，with the frame accounting for 30–40% of the total equipment weight.

• Split frame: Large crushers (capacity >100 t/h) consist of upper and lower frames connected by high-strength bolts (M36–M64, grade 8.8+), facilitating transportation and on-site assembly. The upper frame supports the fixed jaw plate and eccentric shaft, while the lower frame bears the swing jaw and toggle plate seat. A locating spigot (fit clearance ≤0.1 mm) ensures assembly accuracy at the joint.

2. Bearing Housing Bore
   A circular through-hole in the frame’s side walls for mounting the eccentric shaft bearing. The bore diameter is designed per the bearing model (tolerance H7), with wall thickness ≥1/3 of the bearing outer diameter (to enhance load capacity). Step features (10–20 mm deep) at both ends locate the bearing outer ring and seal cover, with an internal surface roughness of Ra ≤1.6 μm (reducing bearing wear).
3. Fixed Jaw Plate Mounting Surface
   An inclined front surface (20°–30° from horizontal, optimizing the crushing chamber profile) with T-slots or bolt holes (150–300 mm spacing) for securing the fixed jaw plate. Flatness ≤0.5 mm/m and perpendicularity to the bearing bore axis ≤0.1 mm/100 mm ensure parallelism between the fixed and swing jaw plates.
4. Toggle Plate Seat Mount
   A concave structure on the frame’s rear wall or lower frame base, connected to the toggle plate seat via bolts or integrally cast. Its surface matches the toggle plate seat (flat or 弧形) to ensure uniform force transmission. Reinforcing ribs (20–50 mm thick) around the mount enhance impact resistance.
5. Reinforcement Structures

• Transverse beams: Large frames feature welded or cast transverse beams (rectangular or I-shaped cross-section) between side walls (500–800 mm spacing) to prevent lateral deformation under load.

• Ribs: Grid-like ribs (50–150 mm high) on the inner frame, with filleted corners (R10–R20) at rib-to-wall/base joints to avoid stress concentration.

6. Auxiliary Structures

• Lifting holes: φ50–φ100 mm holes (threaded or through) on the top/side for handling, with reinforced surrounds (≥30 mm thick) to prevent tearing.

• Discharge adjustment mounts: Bolt holes or slides on the lower frame for installing discharge gap adjusters (e.g., shim packs or wedges) to regulate product size.

II. Casting Process of the Frame (Integral Cast Steel Frame)

1. Mold and Sand Preparation

• Sodium silicate or resin sand molds are used. Wooden patterns (large) or foam patterns (small/medium) are fabricated from 3D models, with 3–5% shrinkage allowance (2–2.5% linear shrinkage for cast steel).

• Mold surfaces are coated with zircon powder (0.5–1 mm thick) for improved finish. Critical areas (bearing bores, mounting surfaces) use cold-hardened sand (surface hardness ≥80 Shore D) for dimensional accuracy.

2. Melting and Pouring

• Low-P/S scrap steel and pig iron are melted in an arc furnace at 1520–1580°C. Composition is adjusted (ZG270-500: C 0.24–0.32%, Si 0.5–0.8%), and deoxidized to ≥99.9% purity (non-metallic inclusions ≤Grade 2).

• A stepped gating system is used, with multi-point bottom pouring (3–5 gates for large frames) at 1480–1520°C. Pouring time is 15–40 minutes (by weight) to ensure smooth filling and avoid slag entrapment.

3. Shakeout and Heat Treatment

• Castings are shakeout after cooling below 200°C. Risers are removed (flame-cut and ground), and surface sand/flash is cleaned.

• Annealing: Heated to 650–700°C, held for 6–8 hours, then furnace-cooled to 300°C for air cooling to eliminate residual stress (≤100 MPa) and prevent post-machining deformation.

III. Machining Process of the Frame

1. Rough Machining

• Using the base plate as a datum, gantry mills rough-mill side walls and fixed jaw mounting surfaces, leaving 5–10 mm finish allowance. Side wall parallelism ≤1 mm/m; mounting surface angle deviation ≤0.5°.

• Bearing bores are rough-bored to 5–8 mm oversize on a horizontal boring machine, with bore axis perpendicularity to the mounting surface ≤0.3 mm/100 mm.

2. Semi-Finishing and Aging

• Surfaces are semi-finished (2–3 mm allowance), and bores are semi-bored (1–2 mm allowance). Artificial aging (200–250°C for 4 hours) further relieves machining stress.

3. Finish Machining

• Fixed jaw mounting surface: CNC gantry-milled to flatness ≤0.1 mm/m, Ra ≤6.3 μm, angle error ≤0.1°.

• Bearing bores: CNC-bored to H7 tolerance with ≤0.05 mm coaxiality between sides, Ra ≤1.6 μm. Step faces at bore ends have ≤0.02 mm/100 mm perpendicularity to the bore axis.

• Holes and slots: Fixed jaw bolt holes (H12 tolerance), toggle seat holes, and T-slots (±0.2 mm width) are machined, with ≤0.5 mm positional deviation from drawings.

4. Surface Treatment

• Unmachined surfaces are sandblasted (Sa2.5) and coated with epoxy zinc-rich primer (60–80 μm) and chlorinated rubber topcoat (40–60 μm) for corrosion resistance. Machined surfaces receive rust-preventive oil (large) or phosphating (small/medium).

IV. Quality Control of the Frame

1. Casting Quality

• Visual inspection: No cracks, shrinkage, or misruns. Critical areas (bearing bore surrounds) undergo magnetic particle testing (MT) to detect surface cracks (length ≤1 mm).

• Internal quality: Large frames undergo ultrasonic testing (UT) with ≥80% coverage. Bearing bores and ribs must be free of ≥φ5 mm inclusions/gas pores.

2. Dimensional Accuracy

• Coordinate measuring machines verify bearing bore diameter (H7), coaxiality (≤0.05 mm), and laser trackers check fixed jaw surface flatness (≤0.1 mm/m) and angle.

• Split frames are inspected for joint surface flatness (≤0.15 mm/m) and spigot fit clearance (≤0.1 mm).

3. Mechanical Properties

• Tensile tests (ZG270-500: ≥500 MPa tensile strength, ≥20% elongation) and hardness checks (180–230 HBW) are performed on samples.

• Water-jacketed frames undergo a 1.5× working pressure hydrostatic test for 30 minutes with no leakage.

4. Load Testing

• A 1.2× rated crushing force is applied for 1 hour. Strain gauges measure maximum stress (≤80% of yield strength), with deformation ≤0.2 mm/m (bearing bore axis offset ≤0.03 mm).

V. Common Chinese-English Names

1. 架体 - Frame

2. 机架 - Crusher Frame

3. 机座 - Machine Base

4. 破碎机架 - Jaw Crusher Frame

5. 主体框架 - Main Frame

6. 支承架 - Supporting Frame