Schematic diagram of double roll sand maker showing material drawn into the gap between counter-rotating rollers by friction, undergoing compression and discharge.
1. Compression Over Impact: Reducing Over-Grinding & Improving Sand Shape
Unlike impact breakers that shatter rock forcefully, a double roll crusher draws material smoothly into the roll gap using surface friction from two independently driven wear-resistant rollers. Materials compress and shear along their natural crystal cleavage planes rather than shattering randomly, delivering distinct advantages:
| Crushing Feature | Impact / VSI Crushers | Double Roll Sand Making Machines |
|---|---|---|
| Primary Mechanism | High-speed kinetic collision / hammer strikes | Squeezing, interparticle compression & shear friction |
| Fracture Pattern | Violent random splitting & impact shatter | Layered cleavage cracking along natural grain boundaries |
| Over-Grinding Rate | Higher percentage of ultra-fine dust (<0.075 mm) | Significantly reduced over-grinding, higher usable sand yield |
| Finished Sand Shape | Variable flakiness; high proportion of elongated particles | Rounded, cubical particles with low needle/flake ratio |
2. Roll Gap Control: Built-In “Physical Screening” for Consistent Gradation
Discharge sizing is directly determined by the gap between the two rollers:
- Compliant Particles: Particles smaller than the set gap exit smoothly along the tangential rotational path.
- Oversized Interception: Particles exceeding the gap setting remain trapped in the compression chamber for further crushing until reduced to the target threshold.
Detailed view of the hydraulic cylinder assembly and sliding bearing block providing auto-relief protection against tramp iron.
3. Automated Hydraulic Relief: Preventing Unplanned Downtime
When uncrushable objects (e.g., tramp iron) enter the chamber, the automated hydraulic protection system detects abnormal pressure spikes. Hydraulic cylinders trigger an immediate gap expansion, allowing the object to pass safely before automatically resetting to the target gap distance for continuous plant operation.
Summary: Substituting violent impact with controlled interparticle compression allows double roll sand making machines to deliver superior particle cubicity, low ultra-fine dust, reliable gradation control, and continuous operating stability.
+86-13838144666
+86-13838144666
