The main advantages would be reduced weight and less complexity.
The rollerjaw rock crusher melds the concepts of jaw crushing and roll crushing long employed in the mining and rock-crushing industries. Rollerjaw rock crushers have been proposed for inclusion in geological exploration missions on Mars, where they would be used to pulverize rock samples into powders in the tens of micrometer particle size range required for analysis by scientific instruments. On Earth, scaled-up rollerjaw rock crushers could be used in mining and rock-crushing operations in which jaw crushers followed by roll crushers or roll mills have traditionally been used. A single rollerjaw rock crusher would be less complex and would weigh about half as much as does an equivalent conventional combination of a jaw crusher and a roller crusher.
In the mining and rock-crushing industries, it is widely recognized that in order to reduce the particle size of minerals, it is often necessary to employ a succession of comminution machines. Jaw crushers are generally used for coarse crushing, cone crushers for intermediate crushing, and roll crushers for producing finer particles. Ball mills and other mills are sometimes used to effect further particle size reduction. In addition, it is sometimes necessary to provide conveyors for transporting crushed rock between successive comminution machines.
A rollerjaw rock crusher (see figure) would include a single actuator and processing wedge gap to perform the functions of a jaw crusher and a roll crusher. The wedge gap would be formed between an actuated jaw-plate and a floating jawplate equipped with a roller at its lower end. The single actuator would consist of a motor-and-gearbox drive that would turn a cam to produce an eccentric motion of the actuated-jaw-plate.
Incoming rocks would be crushed via conventional jaw action in the upper portion of the wedge gap. The rocks would be broken into smaller pieces and squeezed toward the roller in a downward/ inward motion. There would be no need for a separate mechanism to transport rock pieces from the jaw-crushing to the roll-crushing stage.
Once small enough, rock particles would encounter the roller, which, in conjunction with the actuated jaw-plate, would function in a manner similar to that of a conventional roll crusher. It would not be necessary to actively power the roller. A unidirectional mechanism would ensure that the roller rotated only downward on the crushing face. A very small exit gap at the lower end of the wedge gap could be tolerated because the combination of the motions of the actuated plate and the roller would mimic the motion of two rollers during the compression phase of the eccentric-motion cycle. The rotation of the roller would also facilitate clearing of pulverized material that sometimes adheres to the jaw plate surface.
This work was done by Gregory Peters, Kyle Brown, and Stephen Fuerstenau of Caltech for NASA’s Jet Propulsion Laboratory. In accordance with Public Law 96-517, the contractor has elected to retain title to this invention. Inquiries concerning rights for its commercial use should be addressed to:
Innovative Technology Assets Management
Mail Stop 202- 233
4800 Oak Grove Drive
Pasadena, CA 91109-8099
Refer to NPO-44767, volume and number of this NASA Tech Briefs issue, and the page number.