jaw crusher V-Belt

Detailed Introduction to the V-Belt Component of Jaw Crushers

I. Composition and Structure of V-Belts

1. Tensile Layer
   The core load-bearing component, responsible for withstanding tensile loads during transmission and determining the belt’s load capacity. Materials include:

• Cord fabric structure: Multiple layers of dipped polyester cord fabric (or aramid cord fabric) arranged along the belt length, bonded with rubber. It offers good flexibility and is suitable for medium to low loads (e.g., small crushers).

• Wire rope structure: Multiple high-strength polyester cords (or steel wires) evenly distributed circumferentially, with higher tensile strength (≥200 MPa). It is suitable for high-load transmission in large crushers.

2. Top Rubber
   A rubber layer (2–5 mm thick) above the tensile layer, made of a blend of natural rubber (60–70 Shore A hardness) and styrene-butadiene rubber. It has good elasticity, absorbs compressive deformation when the belt bends over pulleys, and reduces stress concentration in the tensile layer.
3. Bottom Rubber
   A rubber layer (3–8 mm thick) below the tensile layer, in direct contact with pulley grooves. Its material contains high-wear carbon black (30%–40% content) to provide sufficient friction (coefficient ≥0.8) for power transmission while resisting abrasive wear from pulley 挤压.
4. Cover Fabric
   An outer layer wrapping the entire belt, composed of multiple layers of dipped canvas (cotton or nylon canvas) bonded by vulcanization. It protects internal structures, enhances belt integrity, and typically features printed markings (model, length, manufacturer).
5. Cross-Sectional Shape
   An isosceles trapezoid with two working surfaces matching the pulley grooves (40° angle, compatible with pulley groove angles). Cross-sectional dimensions (top width, bottom width, height) are standardized by model (e.g., SPB: top width 17 mm, bottom width 11 mm, height 14 mm) to ensure precise fitting with pulley grooves.

II. Manufacturing Process of V-Belts (Rubber V-Belts)

1. Raw Material Preparation

• Rubber Mixing: Natural rubber (50%–60%), styrene-butadiene rubber (30%–40%), carbon black (reinforcer), sulfur (vulcanizing agent), accelerators (e.g., CZ), etc., are mixed in an internal mixer at 120–150°C for 10–15 minutes to produce uniform rubber compounds (Mooney viscosity 60–80).

• Cord/Canvas Treatment: Polyester cords are dipped in resorcinol-formaldehyde-latex solution and dried to improve adhesion to rubber (peel strength ≥5 kN/m). Wire ropes are pre-stretched (tension 5–10 N) for dimensional stability.

2. Belt Blank Forming

• Winding: Cover fabric is wrapped around a circular mandrel, followed by bottom rubber, tensile layers (cords/wire ropes arranged helically with 5–10 mm overlaps), top rubber, and a final cover fabric layer to form an unvulcanized belt blank (length 5%–10% longer than the finished product to account for vulcanization shrinkage).

• Cutting: The annular blank is mounted on a conical drum and cut axially into individual V-belt blanks (trapezoidal cross-section) with smooth, burr-free edges.

3. Vulcanization Setting

• Blanks are placed in pulley molds (with trapezoidal grooves matching the belt cross-section) in a vulcanizing tank. Vulcanization occurs at 140–160°C and 1.5–2.5 MPa for 15–30 minutes (adjusted by thickness), cross-linking rubber molecules to form a stable trapezoidal shape.

• After vulcanization, blanks are demolded, trimmed of flash, and inspected for defects.

4. Post-Processing

• Stretching Setting: Vulcanized belts are stretched on a machine at 10%–15% of rated tension for 30 minutes to relieve internal stress, ensuring length stability (elongation ≤1% during use).

• Marking: Model, length, and manufacturer information are printed on the cover fabric using rubber ink.

III. Quality Control Processes

1. Raw Material Inspection

• Rubber: Test hardness (60–70 Shore A), tensile strength (≥15 MPa), elongation at break (≥300%), and abrasion resistance (Akron wear ≤0.5 cm³/1.61 km).

• Tensile layers: Polyester cords are tested for peel strength (≥5 kN/m); wire ropes for breaking strength (single rope ≥500 N).

2. Dimensional Accuracy Inspection

• Cross-section: Calipers measure top width, bottom width, and height (tolerance ±0.3 mm for SPB); trapezoidal angle deviation ≤1°.

• Length: Laser measuring instruments check inner circumference (deviation ±0.5%, e.g., ±9 mm for 1800 mm). Multiple belts in a set must have consistent lengths (deviation ≤2 mm) to avoid uneven loading.

3. Mechanical Performance Testing

• Tensile Test: Samples are tested for breaking strength (≥10 kN for SPB) and elongation at break (≤3%) to ensure no tensile failure under rated loads.

• Fatigue Test: A simulated pulley test bench runs at 1500 r/min under 1.2× rated load for 1000 hours. Belts must show no cracks, delamination, or length change >2%.

4. Friction and Wear Testing

• Friction coefficient: A pulley friction tester measures static friction between bottom rubber and cast iron pulleys (≥0.8) to ensure no slipping.

• Wear: After 100 hours of wear testing, bottom rubber wear ≤0.5 mm with no exposed fabric or wires.

5. Visual Inspection

• Surface: No bubbles (≤2 bubbles/m with diameter ≤1 mm), missing rubber, or cracks. Cover fabric: No damage or wrinkles. Cross-section: Smooth cuts with no flash.

IV. Key Points for Selection and Maintenance

• Model Matching: Choose based on crusher power and pulley groove type (e.g., SPB for 30 kW motors) to avoid under-sizing (overload) or over-sizing (waste).

• Installation Tension: Maintain proper tension (deflection 1%–2% of span when pressing the belt midpoint). Under-tension causes slipping; over-tension accelerates bearing wear.

• Replacement Cycle: Service life is 3000–5000 hours under normal conditions. Replace when cracks, delamination, or length elongation >3% occur. Replace all belts in a set simultaneously to avoid uneven loading.