Boring or penetrating the earth – Automatic control
Patent
1996-03-18
1997-12-30
Dang, Hoang C.
Boring or penetrating the earth
Automatic control
173 6, 175122, E21B 302, E21B 702
Patent
active
057019622
DESCRIPTION:
BRIEF SUMMARY
The invention relates to an arrangement in the feed mechanism of a rock drill, said arrangement comprising a feed beam, a feed cylinder the piston rod of which is arranged to be stationary in the longitudinal direction of the feed beam whereas the cylinder sleeve of said feed cylinder is mobile in the longitudinal direction of the feed beam, a feed mechanism arranged to be driven by the feed cylinder for providing the feed and the return motion of the rock drill, a control mechanism for controlling the feed mechanism of the rock drill, an indicator connected so that it moves in the same direction as the rock drill for indicating the position of the rock drill, and at least one sensing element which detects the indicator when the indicator reaches a predetermined position with respect to the sensing element and supplies to the control mechanism a control signal necessary for controlling the motions of the rock drill.
At present, rock drills are controlled by various sensing elements, typically inductive or hydraulic switches. These switches are positioned outside the feed beam in separate boxes at the front and the rear end of the feed beam. The indicator or control pieces that are required for the control are attached to drill carriages moving along the feed beam in such a manner that they extend outside the feed beam. If these solutions are implemented electrically, they are rather easily broken and, in order to be able to operate, require complicated control connections. In addition, the cables needed for the connection are long and difficult to protect in use. Correspondingly, if the solutions are implemented hydraulically, the long hydraulic hoses that are required are difficult to protect and easily broken.
The object of the present invention is to provide an arrangement by which the previous drawbacks can be avoided and by which the indicators, and the sensing elements functioning with the help of them, can be easily mounted in a reliable and secure manner. A further object of the invention is to provide an arrangement in which the sensing elements are simple and easy to connect and in which short connection cables or hoses can be used. The arrangement according to the invention is characterized in that each sensing element is mounted on the feed beam of the rock drill somewhere along the travel of the cylinder sleeve, that each indicator is secured to the cylinder sleeve so as to move together with it so that when the rock drill reaches a predetermined position with respect to the feed beam, the indicator secured to the cylinder sleeve causes the corresponding sensing element to supply a control signal to the control mechanism.
An essential feature of the invention is that the sensing element or elements are mounted somewhere along the travel of the cylinder sleeve of the feed cylinder, preferably close to the centre of the feed beam, in such a manner that the sensing area extends inside the feed beam and the sensing elements are well protected against external effects. It is another essential feature of the invention that the indicators are secured to the cylinder sleeve of the feed cylinder so that when the cylinder sleeve is moving, they can activate the sensing elements and thus control the feed and the return motion.
An advantage of the invention is that the sensing elements are positioned within the feed beam, in the centre of it, well protected against external effects, such as falling stones. Another advantage of the invention is that the control cables or hoses are short, and it is relatively easy to mount them so that they are protected. In addition, it is easy and simple to adjust the limits of the arrangement, as the indicators can be easily displaced along the cylinder sleeve of the feed cylinder. Thus it is easy to provide accurate control.
In the following, the invention will be described in greater detail with reference to the accompanying drawings, in which
FIG. 1 is a schematic, partly sectional side view of the arrangement according to the invention,
FIG. 2 is a schematic top view
REFERENCES:
patent: 3561542 (1971-02-01), Hanson
patent: 3807510 (1974-04-01), Boom et al.
patent: 4074771 (1978-02-01), Morrison
Dang Hoang C.
Tamrock Oy
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