Evaluation of diamond bead wire saw evaluation of diamond bead wire saw

At present, diamond bead wire saws have been widely used in stone mining, block shaping, special-shaped stone sawing, and building renovation and construction. To use the diamond bead wire saw correctly to improve its working efficiency and service life, it is necessary to evaluate the diamond bead wire saw for on-site use.
M.Cardu and A.Giraudi, the Politecnico di Torino, Italy, and V.Murthy, the Indian Institute of Mining, conducted diamond ropes at the Carrara marble quarry in Italy and the Ambaji marble quarry in India. The site of the saw uses the evaluation work. Performance analysis was used to compare the practical performance of the newly used diamond bead wire saw and suggested improvements in productivity and wire saw life. Now we will introduce the research work as follows.
1 Quarry Overview
The Carrara marble mine in Italy is located in the Colonnata basin. There are 29 quarrying operations producing high-quality marble in pure white, light green and beige colors. It is an excellent material for statues and buildings, with an annual output of 145. 000m3, since the use of the diamond beaded wire saw has completely abandoned the blast mining method, but the cracked huge rock mass that can not be exploited to use the explosive method to remove.
The Ambaji marble quarry in India is located in the state of Gujarat, India's high-quality white marble producing area with an annual output of more than 120,000 tons. At present, about 15,000 m2 of glossy marble plates can be produced per month. The quarry area has a very thick cover that must be excavated in order to extract the marble bench below. At present, the excavation of the cover layer adopts the explosion method. In order to prevent the lower rock body from being destroyed, the explosion scale was limited. Most of the cover layer is microcrystalline silica, with a certain hardness and abrasiveness, so the use of explosive method is the fastest and lowest cost. However, it is still impossible to avoid the explosion caused by the collapse of rock mass and affect the mining rate.
2 Marble properties of quarry
During diamond bead sawing, the diamond bead interacts with the rock and the sawing speed depends to a large extent on the physical and mechanical properties of the rock. Therefore, it is necessary to test the texture of the sawn rock. M. Cardu et al. performed the S20 brittleness test, the CAI Secal grindability test, and the Knoop microindentation hardness test on the marbles of the above quarry.
2.1 S20 Brittleness Detection
This detection method reliably detects the rock's crush resistance. The specific method is: in the concrete with a 14kg heavy hammer hit a certain amount of rock samples 20 times, with 11.2mm mesh sieve, the percentage of rock fragments sampled is the brittleness value. Usually a rock sample is tested at least 3 times and the average value is taken as the brittleness value of the rock.
2.2 CAI Secchar abrasive testing
The abrasiveness of the rock is measured to predict the wear performance of the diamond tool. The method is to use a 90° conical steel needle to scratch a length of 10mm on the rock sample, and the steel needle must be pressed into the surface of the rock sample with a force of 70N (Newton).
The Secor's abrasive index is usually expressed in CAI and is measured on the wear plane of the steel needle in units of 1/10mm. During the measurement, two photographs shall be taken for each steel needle in order to measure the wear plane in two perpendicular directions and take the average value.
2.3 Knoop microindentation hardness test
This is a typical microhardness test method using a round head hardness tester, which is ideal for hardness testing of brittle and hard materials. The durometer head is a slender, diamond-shaped pyramid with an apex angle of 130° and 172°30'. The applied pressure was 1.96N. In the standard Knoop hardness test, the longest diagonal of the impression on the sample is measured. Knoop hardness (HK) is calculated by the formula: HK=14230·P·l -2
Where P - the load applied to the indenter, N; l - the longest diagonal length of the indentation measured on the sample, in microns. HK value is expressed in MPa.
3 Diamond bead wire saw technical specifications and usage
The diamond beaded wire saw is composed of diamond beads strung in a high-strength fine steel wire rope, and the diamond beads are fixed with a rubber spacer or a plastic injection or a spring. Diamond beads are made by inserting a diamond package in a metal carcass. There are three different ways of inlaying, namely electroplating, sintering and vacuum brazing. Diamond bead diameter is generally 7.5 ~ 11.5mm, can meet the marble, granite, limestone, sandstone and other sawing and forming cutting needs, and its working speed is about 30 ~ 40m / s.