Ball Mill Feeding Machine

Detailed Introduction to Ball Mill Feeders and Their Manufacturing & Inspection Processes

I. Functions and Types of Ball Mill Feeders

1. Classification by Structure and Working Principle

• Screw Feeder

• Structure: Composed of a screw blade, conveying trough, drive motor, and reducer. Materials are pushed by the rotation of the screw blade.

• Characteristics: Excellent sealing (suitable for dusty or toxic materials), with feed quantity adjustable via speed control. Applicable to granular or powdery materials (e.g., pulverized coal, cement raw meal) but prone to clogging with viscous materials.

• Belt Feeder

• Structure: Consists of a conveyor belt, idlers, drive drum, tensioning device, and speed-regulating motor. Materials are conveyed by friction between the belt and materials.

• Characteristics: Large feeding capacity (up to hundreds of tons per hour) and strong adaptability (capable of conveying large lumps, such as ores). However, it has poor sealing and requires a dust cover.

• Vibrating Feeder

• Structure: Includes a trough, vibration motor (or eccentric shaft vibrator), and spring supports. Materials slide down the trough via periodic vibration.

• Characteristics: Enables uniform and continuous feeding, and can simultaneously screen materials (with a screen at the trough bottom). Suitable for 块状 and granular materials (e.g., iron ore) but may crush brittle materials.

• Plate Feeder

• Structure: Composed of chain plates, sprockets, and a drive unit. Chain plates are made of wear-resistant steel plates, and materials are conveyed via chain transmission.

• Characteristics: Extremely high load-bearing capacity (capable of conveying large lumps weighing ≥1 ton), suitable for feeding coarsely crushed materials into large ball mills (e.g., mining ball mills). However, it is bulky and costly.

2. Core Performance Requirements

• Feeding uniformity: Fluctuation ≤±5% (to ensure stable ball mill load);

• Wide adjustment range: Feeding quantity can be steplessly adjusted within 20%-100% of the design value;

• Wear resistance: Components in contact with materials (e.g., screw blades, belts, chain plates) must use wear-resistant materials (high manganese steel, wear-resistant cast iron);

• Reliability: Mean time between failures ≥8,000 hours.

II. Manufacturing Process of Ball Mill Feeders

1. Key Component Manufacturing

• Trough (core component in contact with materials)

• Material: Small to medium-sized troughs use Q355B steel plates (8-12mm thick); large or high-wear troughs use ZGMn13 high manganese steel (15-20mm thick).

• Manufacturing process:

1. Blanking: CNC cutting of steel plates, ensuring length and width tolerances of ±2mm;

2. Forming: Bending the trough sides with a bending machine (angle 90°±1°), and welding stiffeners (spacing 300-500mm to enhance rigidity);

3. Welding: Gas shielded welding for seams, followed by stress relief annealing at 200℃ for 2h. Welds must pass MT inspection (Grade II);

4. Surface treatment: Sandblasting (Sa2.5 grade), then spraying wear-resistant coating (e.g., tungsten carbide, 0.3-0.5mm thick) or surfacing with wear-resistant electrodes (hardness ≥55HRC).

• Vibration Motor and Vibrator

• Vibration motor: Purchased as standard products (e.g., YZU series) with matching exciting force (5-50kN, calculated based on trough weight and feeding quantity).

• Eccentric shaft vibrator (non-motor-driven type):

1. Shaft: Forged from 45# steel, quenched and tempered (hardness 220-250HBW), with outer circle tolerance IT6 and surface roughness Ra≤1.6μm after finish turning;

2. Eccentric block: Cast from HT300, subjected to static balance testing after rough machining (unbalance ≤5g·cm), and connected to the shaft via a key (H7/k6 fit).

• Spring Support Device

• Material: 60Si2Mn spring steel, cold-coiled and then quenched (860℃ oil cooling) + medium-temperature tempered (420℃), with hardness 45-50HRC and free length tolerance ±1mm.

2. Assembly Process

1. Frame welding: Welding the frame with Q235B angle steel, followed by stress relief annealing (300℃×2h) to ensure frame perpendicularity ≤1mm/m;

2. Component installation:

• Spring supports are bolted to the frame and trough (bolt preload torque meets design requirements, e.g., 350N·m for M20 bolts);

• The vibrator is installed at the trough's center of gravity, rigidly connected to the trough via bolts, ensuring the vibrator axis is parallel to the trough's centerline (deviation ≤0.5mm/m);

3. Electrical system assembly: Installing a speed-regulating motor, frequency converter (1.5-15kW, frequency range 5-50Hz), and control system (capable of remote feeding quantity adjustment);

4. Trial operation: Running no-load for 2 hours to check vibration stability (amplitude deviation ≤0.2mm), noise (≤85dB), and absence of looseness or jamming.

III. Inspection Process of Ball Mill Feeders

1. Raw Material and Component Inspection

• Material inspection:

• Wear-resistant parts (high manganese steel ZGMn13): Spectral analysis to verify Mn content (11-14%), hardness ≥200HBW (≥300HBW after aging);

• Spring steel (60Si2Mn): Tensile testing to check tensile strength ≥1270MPa, yield strength ≥1100MPa, and impact toughness ≥60J/cm².

• Component dimension inspection:

• Screw blades: Pitch tolerance ±2mm, blade thickness deviation ≤-0.5mm (to avoid jamming due to excessive thickness);

• Vibrating trough: Length and width measured with a steel tape (tolerance ±5mm), and trough bottom flatness ≤3mm/m (detected with a level).

• Heat treatment inspection:

• Eccentric shaft: Hardness 220-250HBW (Brinell hardness tester), with quenched-tempered layer depth ≥1/3 of the shaft diameter;

• Spring: Hardness 45-50HRC (Rockwell hardness tester), subjected to compression testing (compressed to 1.5 times the working stroke, held for 10min with no permanent deformation).

2. Assembly Inspection

• Static accuracy inspection:

• Frame perpendicularity: Detected with a laser level, deviation ≤1mm/m;

• Vibrator installation accuracy: Parallelism between the vibrator and trough measured with a dial indicator, deviation ≤0.5mm/m.

• Dynamic performance inspection:

• No-load test: Running for 2 hours, recording amplitude (with an amplitude meter), bearing temperature rise (≤40℃, ambient temperature +40℃), and checking for no loose fasteners (no torque change after rechecking);

• Load test: Step loading at 50%, 100%, and 120% of the design feeding quantity, running for 1 hour per step. Feeding uniformity is detected by weighing (5 consecutive weighings, deviation ≤±5%);

• Overload test: Running at 150% of the design load for 30 minutes, checking for no plastic deformation of the trough or springs.

3. Final Acceptance

• Appearance quality: Surface coating (primer + topcoat) thickness ≥80μm (measured with a coating thickness gauge), no runs or peeling, and clear markings (model, feeding quantity, weight);

• Safety performance: Emergency stop button response time ≤0.5s, protective cover IP rating ≥IP54 (dust-proof);

• Technical documents: Providing a product certificate, operation manual (including installation diagram and maintenance cycle), and material reports for key components.

IV. Summary