Studs are key wear-resistant components on High-Pressure Grinding Rolls (HPGR), typically made of high-hardness alloys (e.g., high-chromium cast iron, tungsten carbide) to enhance crushing efficiency and protect roll surfaces. Their manufacturing process involves material selection (with chemical composition verification), forming (casting for high-chromium alloys or powder metallurgy for tungsten carbide), heat treatment (quenching/tempering or stress-relief annealing), and surface treatment (anti-corrosion coatings, polishing).
Detailed Introduction to Studs in High-Pressure Grinding Rolls (HPGR)
Studs are critical wear-resistant components mounted on the surface of HPGR rolls, designed to enhance material crushing efficiency and protect the roll surface from excessive abrasion. Typically made from high-hardness alloys (such as high-chromium cast iron, tungsten carbide, or composite materials), these cylindrical or conical projections create a rugged surface that grips and crushes bulk materials (e.g., ores, minerals, or aggregates) as the rolls rotate under high pressure. Their arrangement—often in staggered patterns—ensures uniform material penetration and reduces slippage, directly influencing the HPGR’s throughput and particle size reduction performance.
Manufacturing Process of HPGR Studs
Material Selection and Preparation
Choose raw materials based on application requirements: High-chromium cast iron (for moderate abrasion) or tungsten carbide composites (for extreme wear resistance).
Verify material chemical composition via spectroscopy to ensure hardness (e.g., ≥60 HRC for high-chromium alloys) and tensile strength meet standards.
Preprocess materials (e.g., melting alloys in induction furnaces at 1500–1600°C to achieve homogeneity).
Forming
Casting: For high-chromium studs, use sand casting or investment casting to form the basic shape. Molds are designed with precise dimensions to match stud length (typically 50–150mm) and diameter (10–30mm).
Powder Metallurgy (for tungsten carbide studs): Mix tungsten carbide powder with a binder (e.g., cobalt), compact into dies under high pressure (100–300 MPa), and sinter at 1300–1500°C in a vacuum furnace to achieve densification.
Machining: Use CNC lathes or grinding machines to refine dimensions, ensuring consistent length, diameter, and tip sharpness (for conical studs).
Heat Treatment
For high-chromium cast iron studs: Quench at 900–1000°C followed by tempering at 200–300°C to enhance hardness and toughness, reducing brittleness.
For tungsten carbide studs: Post-sintering heat treatment is minimal, as sintering already achieves desired hardness; instead, perform stress-relief annealing to eliminate residual stresses.
Surface Treatment
Apply anti-corrosion coatings (e.g., nickel plating) for studs used in humid or chemical environments.
Polish contact surfaces to ensure smooth integration with the roll surface.
Quality Inspection Process
Dimensional Inspection
Use calipers, micrometers, and coordinate measuring machines (CMM) to verify length, diameter, and tip geometry, ensuring compliance with design tolerances (typically ±0.05mm).
Check surface roughness via profilometers, requiring Ra ≤ 1.6μm to prevent material buildup.
Material Property Testing
Conduct hardness tests using a Rockwell hardness tester (HRC scale) to confirm hardness meets specifications (e.g., 60–65 HRC for tungsten carbide studs).
Perform tensile and impact tests on sample studs to evaluate mechanical strength and fracture resistance.
Microstructural Analysis
Use optical microscopes or scanning electron microscopes (SEM) to inspect internal structures, ensuring uniform grain distribution and absence of cracks, porosity, or inclusions.
Adhesion Testing (for mounted studs)
For studs welded or bonded to rolls, perform shear tests to verify bonding strength (minimum 50 MPa) and check for delamination.
Wear Resistance Testing
Conduct accelerated wear tests using abrasive materials (e.g., quartz sand) to simulate real-world conditions, measuring weight loss over 100 hours of operation. Acceptable wear rates are ≤0.1g/h.
Final Visual Inspection
Inspect for surface defects (scratches, dents, or uneven coatings) and ensure consistent color and finish across all studs in a batch.
By adhering to these manufacturing and inspection processes, HPGR studs can maintain optimal performance, extending the service life of high-pressure grinding rolls in demanding industrial environments
