Multi-Mull for Mixing Green Sand and Water Glass Sand in Sand Casting

The sand mixer that mixes the sand mixture through the grinding and kneading of the grinding wheel is called the grinding wheel sand mixer.
The grinding wheel sand mixer is an intermittent sand mixer, mainly used for the mixing of green sand. It is equipped with two grinding wheels, two scrapers, the grinding wheel has the role of grinding, rubbing, so that the water, clay, other additional materials evenly distributed in the surface of the sand, scrapers to loosen the sand, and not mixed sand scraped under the grinding wheel, continue to grind, rubbing, until all mixed sand.
In the wet sand casting process, the uniformity of the molding sand directly affects the surface quality and yield rate of the casting. The grinding wheel sand mixer has become a benchmark equipment for sand processing in small and medium-sized foundries due to its unique grinding wheel mechanism and intermittent high-efficiency mixing ability. This article will deeply analyze how this equipment reshapes the process standard of wet sand mixing with the performance indicators of 98% mixing uniformity and energy consumption per ton of sand ≤1.5kW·h from the dimensions of technical principles, structural design, core advantages and industry applications.


1. Technical principles and core design breakthroughs
Based on the mixing characteristics of wet sand (water content 3-5%, clay content 8-12%), the roller sand mixer achieves technical breakthroughs through the roller-scraper synergy system:
Double roller grinding mechanism:
High manganese steel roller (diameter Φ800-1500mm, hardness HB 350-400) rotates at a low speed of 5-10r/min, crushing sand agglomerates through the dual effects of rolling and kneading. The clay coverage rate on the surface of sand particles is greater than 95%, and the air permeability of molding sand is increased to more than 120cm³/min;
Dynamic pressure adjustment: roller deadweight + hydraulic booster system (pressure adjustable range 0.2-0.8MPa), adapted to the hardness requirements of different sand molds (silica sand, chromite sand), to avoid sand crushing caused by over-rolling (crushing rate <0.5%).
Scraper circulation system:
Bidirectional adjustable scraper: Tungsten carbide coated scraper (thickness 10mm) scrapes the bottom sand layer at an angle of 15°-30°, ensuring that each batch of sand is rolled ≥5 times and the mixing uniformity is >98%;
Anti-sticking sand design: The gap between the scraper and the roller is dynamically adjusted (1-5mm) to prevent wet sand from sticking and reduce cleaning downtime.


Intermittent intelligent control:
The PLC control system presets a sand mixing cycle of 8-12 minutes/batch, and supports automatic feeding of multiple components such as clay, coal powder, and water (accuracy ±0.3%);
Frequency conversion motor drive (power 15-37kW), energy consumption per ton of sand ≤1.5kW·h, which saves 25% energy compared to traditional continuous sand mixers.


2. Core advantages and industry value
Compared with high-speed rotor sand mixer, the roller design achieves multi-dimensional upgrades through low wear rate and high uniformity:
Excellent mixing quality:
The wet compressive strength fluctuation of the molding sand is ≤0.5kPa, the compaction rate error is ±1%, and the surface pore defect rate of the casting is reduced to below 0.3%;
The clay activation rate is >90%, the effective bentonite utilization rate is increased by 30%, and the annual clay cost is saved by more than 80,000 yuan (based on 3,000 tons/year usage).
Durable and low maintenance:
The roller life is >5 years (the life of ordinary cast iron grinding wheels is only 2 years), and the replacement time is <2 hours;
Flexible adaptability:
The mixing amount is 0.5-3 tons/batch, which is suitable for the production of single-piece small batch castings, and the mold change time is <10 minutes;
The resin/curing agent injection module can be optionally equipped to expand to the cold core box sand and water glass sand mixing process.