Saw, Stonecutting

the working member of a stonecutting machine. Stonecutting saws are divided into circular saws, ring saws, chain cutters, and cable saws.

Circular saws for cutting soft rocks, such as limestones and tuffs, are made from sheet steel of 800–2,000 mm diameter and 10–20 mm thickness. The cutting teeth are mounted on the periphery of the disk, with the teeth spaced 80–120 mm apart. They are reinforced with hard-alloy plates. The peripheral cutting speed is 2.5–6 m/sec.

Hard rocks, such as marble, gabbro, and granite, are cut by stationary machines equipped with circular saws that are coated with natural or synthetic diamond dust, which is bonded to the blade with a metallic binder. These saws may be in the form of cutoff disks that have a 50–320 mm diameter, a 2.5–5 mm thickness, and a continuous cutting surface. They may also consist of cutting disks that are 300–1,100 mm in diameter (sometimes up to 3,000 mm) and 60–90 mm thick and have a segmented cutting surface. The peripheral cutting speed is 25–60 m/sec. Circular saws have the advantage of simplicity of design and use; their disadvantage is that only about 35 percent of the diameter is used for cutting.

Ring saws resemble ball-bearing assembly. An inside ring is rigidly attached to the frame of the stonecutting machine, and an outside ring carries teeth that have an involute profile and are reinforced with a hard alloy. These teeth are engaged with a driving gear and produce a cut that is 35–40 mm wide. The advantage of ring saws is that about 65 percent of their diameter is used in cutting. Capable of making cuts 0.8–1.2 m deep, they are widely used for cutting large blocks. However, they are complex in design and complicated to use.

Chain cutters are used in special stonecutting machines for cutting individual stones and in universal cutting machines for cutting large blocks. They are also used for making initial plow cuts. Chain cutters produce a cut that is 20–40 mm wide. They can be used for cutting stone with a comprehensive strength of up to 50 kilograms-force per sq cm (kgf/cm²). Designs have been developed capable of cutting rocks with a comprehensive strength of about 800 kgf/cm².