Prospects for percussion sawing machines in production of high-strength dimension stone

Abstract

One of the most labor-intensive operations in production of dimension stone is separation of a stone monolith from rock mass, cutting of the monolith into blocks and sawing of the blocks into slabs. This article reviews in brief the methods of cutting and sawing of high-strength rocks. The new method of percussion sawing is described. Based on the method, the structural layouts of machines for cutting and sawing of stone blocks are proposed. The percussi on sawing method is efficient in brittle hard and super-hard rocks such as granite and sometimes marble, with Protodyakonov-scale hardness from 6 to 20. The method provides high quality finishing of surfaces at average productivity and low cost of sawing. The authors describe various structural layouts and operation modes for different percussion sawing machines suitable for operation in stone quarries, stone working plants and workshops. The basic elements of percussion sawing machines are frame, percussion assembly, tooth saw, vertical and horizontal feed drives, and the cut blowing or washing facilities. The article describes the machine capacity calculation procedure confirmed by the experimental research data. The major machine parameters to affect its capacity are: blow energy of the percussion assembly, number of percussion assemblies, saw area at the contact with stone, seesaw velocity, and ultimate compression strength of stone. A new estimated figure is put forward as specific blow energy per kerf bottom surface. The change in the capacity of a quarry percussion sawing machine as a function of time of one saw pass is determined. The obtained relation is compared with performance of other two types of sawing machines.The comparative analysis of mechanical methods of hard rock sawing is performed. The efficiency of the proposed method for percussion sawing of hard and super hard rocks is proved.