WO2007136271A1

WO2007136271A1 - A cutting system

Info

Publication number: WO2007136271A1
Application number: PCT/NO2006/000191
Authority: WO
Inventors: Oddbjørn SKJÆRSTAD
Original assignee: Global Tool Management As
Priority date: 2006-05-19
Filing date: 2006-05-19
Publication date: 2007-11-29

Abstract

A cutting system for cutting steel and concrete structures, where each of two legs of a U-shaped frame (5) comprises each one arm (2, 3), one of which being connected to a motor (4), adapted to tension a rod (1) covered with diamonds, said arms (2, 3) being adapted to displace the rod (1) to and fro in the direction of the axis of the rod, the motor (4) being adapted to rotating the rod (1) simultaneously with the axial displacement, and said frame (5) being secured to a feeding arrangement (6) clamped to the structure to be cut and providing movement of the frame (5) corresponding with the cut in the structure.

Description

A cutting system

The present invention is related to a cutting system for cutting steel and concrete structures, according to the preamble of the claims.

Cutting structures with diamond wires is well known and frequently used. However, the use of diamond wire cutting machines in narrow spaces, and for applications where a full scale diamond wire machine is unnecessary or unpractical there was a need for a more suitable way to cut such structures. One such example is cutting of wall mounted pipe lines in nuclear power plants, where pipes were located very close to the back wall and the necessary over-shoot needed for a diamond wire based machine could not be realized. Such pipes were also exposed to bending forces which made problems for conventional cutting equipment. A diamond wire based equipment needs to handle at least 2.5 meters of diamond wire, which is the shortest practical length that can be produced as a closed loop. Even these short loops will make the cutting equipment large. Another factor is that the wire loop transports cooling media and chips from the cutting object over a large area. This is a disadvantage when the equipment is used in contaminated areas. As readily can be understood a diamond wire machine is a large equipment demanding space at and around the cutting area.

The cutting system according to the present invention provides equipment suitable for handling situations as described above, said cutting system being suitable for cutting operations an land as well as offshore and also for sub-sea use. The advantages described are achieved with the cutting system according to the present invention as defined by the features stated in the claims.

In the drawing figure 1 discloses the cutting system equipment in a perspective view and figure 2 discloses the cutting system equipment in a ground view.

A diamond covered rod 1 is tensioned between two arms 2, 3 secured to a U- shaped frame 5, one of the arms 3 having a motor 4 to rotate the rod at high speed. Said frame 5

To control the rod 1 during cutting operations the rod 1 has to be pre-tensioned. This is achieved by forcing the arms 2, 3 in opposite directions with preferably a mechanical device. The force used will typically be from 200 to 300 kg, depending on the core material of the rod 1.

The machine uses an oscillating movement of the diamond rod 1 to ensure that the rod will wear evenly. This is done by moving the arms 2, 3 fore and aft during cutting, thereby to displace the rod.1 A feeding arrangement 6 is used to move the diamond rod 1 through the cutting object. This feeding arrangement 6 has been designed to adapt to the gradual wear of the diamond rod 1. The machine is attached to the structure to be cut with a clamping device 7 that is tailor-made for each specific cutting object. Such machines will be produced in two different types; one for sub-sea use, and one for on-shore use, whereby the main differences between them are a result of the environments they will be used in. The sub-sea version will have a ROV interface, and use the built-in hydraulics and control system of the ROV. It will be designed to minimize the effect of water currents, and have motors, cylinders and sensors that can withstand high water pressures. The on-shore version will be designed for use in nuclear power plants and other demanding environments, and will have a smooth surface that makes it easy to clean. This version can be interfaced against remote controlled robots or other tool carriers, and either take the hydraulic power from the robot or from a external hydraulic power pack. Built-in or external control systems will be used. The circular cross section of the rod 1 gives it the same advantages as a diamond wire in cutting operations where parts are exposed to compression or bending forces. A rod 1 according to the present invention, however, will never stick as conventional cutting equipment based on blades or similar technology.

The rod 1 itself is a high tensile steel rod, preferably of 10 mm outer diameter and covered with diamonds. Said rod 1 will be provided at a variable length according to the specific object to be cut. Nominal rotation speed for the rod is 7500 rpm with a pretension of 300 kg. Very little force is needed to maintain this speed during cutting, and this makes it possible to use very small electric or hydraulic motors on the cutting equipment. The rod 1 is oscillated from side to side during the cutting operation with a frequency of 0.5 - 1 Hz, and an amplitude of ± 50 — 100 mm. A constant feeding force is used which takes consideration to the wear of the rod.

As compared with a diamond wire the diamond rod 1 according to the present invention has only one wearable part, namely the rod 1 itself. On a diamond wire based machine on the other hand it is also necessary to change the liners on 2 — 5 wheels, or the whole wheel in some designs, as these as exposed to heavy wear from the wire.

The cutting system according to the present invention is well suited to sub-sea cutting operations, both diver assisted and remote controlled operations. It is for example much less hazardous to a diver than a diamond wire machine.

With the cutting system equipment according to the present invention all cutting parameters easily can can be monitored and adjusted during operation.

Claims

P a t e n t C l a i m s

1. A cutting system for cutting steel and concrete structures, characterized in that each of two legs of a U-shaped frame (5) comprises each one arm (2, 3), one of which being connected to a motor (4), adapted to tension a rod (1) covered with diamonds, said arms (2, 3) being adapted to displace the rod (1) to and fro in the direction of the axis of the rod, the motor (4) being adapted to rotating the rod (1) simultaneously with the axial displacement, and said frame (5) being secured to a feeding arrangement (6) clamped to the structure to be cut and providing movement of the frame (5) corresponding with the cut in the structure.