Rockbolt monitor

Details Rockbolt monitor Rockbolt monitor

1991-06-13

1993-02-09

Swann, III, Glen R.

Communications: electrical

Condition responsive indicating system

Specific condition

73784, 340540, 340665, 340686, 340691, C08B 2100

Patent

active

051855950

ABSTRACT:
A rockbolt monitor monitors increased loadings on a rockbolt in underground mines. The monitor includes a rockbolt plate fitted on the rockbolt to engage the surface of the rock, a stack of belleville washers on the end of the rockbolt outside the rockbolt plate and a spring seat plate outside the belleville washers. When a nut is fitted onto the rockbolt and torqued, the belleville washers will compress to provide the desired force urging the rockbolt plate against the surface of the rock. This spring arrangement allows relative movement of the rockbolt plate on the rockbolt in response to ground movement, such as caused by blasting. The load indicator itself includes a threaded sleeve screwed into a threaded bore in the spring seat plate. A spring loaded piston rides in the sleeve. It is biased into engagement with the rockbolt plate. The amount by which the outer end of the piston projects from the end of the sleeve is a measure of the amount of rockbolt plate movement and rockbolt loading that is taken place since installation. To provide a qualitative signal of this having occurred, the piston desirably has an outer end that is painted black and a section adjacent the outer end that is painted red. When the red portion is shown, the rockbolt plate has moved on the rockbolt. The indicator may also include a plunger to signal loosening of the rockbolt or an electric switch operable by the piston to produce an alarm signal when the rockbolt plate moves. Another embodiment of the invention involves two telescoping sleeves, one mounted on the rockbolt plate and the other on the spring seat. The outer sleeve has slots in it through which the inner sleeve movements can be observed.

REFERENCES:
patent: 3111655 (1963-11-01), Kotarsky et al.
patent: 3826128 (1974-07-01), McVey et al.
patent: 4097854 (1978-06-01), Black et al.
patent: 4136556 (1979-01-01), Graham
patent: 4426642 (1984-01-01), Doffenbarger

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