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Abstract

The wear evolution and its influence on drilling parameters were also measured. These measurements provided important input parameters into a semi-empirical physical drilling model based on indentation theory. The basis model along with a comparison between drilling performance and actual drilling test results are presented on paper. All drilling models for diamond impregnated segments on which this PCD model.

The experimental development of the optimum core to match the available drive parameters, therefore complemented by modelling.The first phase towards a full system development of tool, accessories and core bits for drilling in reinforced concrete.


1.      Introduction

PCD has been successfully used for both rock drilling and metal cutting, up to now it has not been commercially applied for the simultaneous cutting of both mineralic and metallic materials in the case reinforced concrete. In the dismantling of decommissioned nuclear facilities and drilling in water-sensitive environments such as hospitals, computer server rooms, etc. The first application in particular is extremely challenging. The cutters are more efficient and more universal for diamond impregnated segments and therefore provide measurable customer benefits. The widespread penetration of this technology into mainstream building and construction markets is dependent on reducing specific core drilling costs per unit depth, which can only be achieved when the excellent drilling performance is matched by guaranteed reliability and long lifetime.
Ever since the first products were available to specialized decommissioning and dismantling
Sub-contractors in 2004, only standard tools have been available and core bit designs have been adjusted to optimize performance under the available drilling parameters. In the future developments will concentrate in the drilling system, with the Diamond cutter, tool, rig, bit, hole starting points and air flushing system under investigation. The drilling model addresses the issue of cutter, bit and drive parameters and can be used in a predictive manner as well as having a descriptive character. Bit speed and lifetime in concrete can be fairly reliably predicted within the boundary limits of the model, although it has not been extended to the case of the rebar.



Drilling model

The model is based on wedge indentation theory, and is a modified  “Reversed hardness model”, PCD indentation depth and calculating penetration per Revolution in a concrete of known “hardness” and “drill ability”. This is transferred into Heat = 1600 J/mm3Di drilling speed values. Three different end-of-life criteria are considered, based on wear and fracture. The influence of wear on drilling speed is taken into consideration by the models’ continuous adjustment of the primary input parameters in 1mm drilling depth increments. This differs from the related model for diamond impregnated segments , where ideal and steady-state conditions are assumed. A number of input parameters are necessary to achieve useful output from such a model. Many parameters can be measured directly, while others must be determined in the validation and calibration stages of modeling, by comparing model outputs with actual values and adapting the input values to achieve closer correlation if necessary. The disadvantage of this type of modeling  energetic modeling is that the geometrical and physical properties of the tribosystem must be well characterized for modeling to have any degree of accuracy, whereas the energetic approach integrally describes material demolition in the macro- and micro-domains without needing such specific inputs.

Core drilling in reinforced concrete using polycrystalline diamond (PCD) cutters

The production and application of core drill bits, rigs and motors give the edge in the market. Our products can be viewed as innovative solutions for large-scale projects while remaining cost-effective for everyday construction site use.