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Large-scale Laboratory Drag Cutter Experiments in Hard Rock.

Morrell RJ; Larson DA; Swanson DE
MISSING :18 pages
The Bureau of Mines conducted a series of laboratory experiments to test a cutting technique for hard rock using large-scale drag cutters. Cutting experiments were performed on rocks ranging in compressive strength from 10,000 to 27,000 lb/in2, using large drag cutters from 3 to 6 in. In width. The tests were conducted on a special test apparatus, called a ripper tester, which made a curvilinear cut across the rock sample while measuring the cutting force acting on the drag cutter. The cutting method that evolved from these experiments is called ripper cutting, and its energy efficiency appears superior to all other large-scale mechanical fragmentation techniques. In addition, the method created very little dust, and the wear on the bits was negligible. A fragmentation system based on ripper cutting was then devised, and a large-scale test device was fabricated to allow full-scale laboratory testing of the system. The results of these tests will be published in future Bureau reports.
Publication Date
Document Type
IH; Report of Investigations
Fiscal Year
Identifying No.
RI 9003
NIOSH Division
Source Name
Page last reviewed: November 12, 2021
Content source: National Institute for Occupational Safety and Health Education and Information Division