Roof Micrometer And Warning Instrument

Abstract

A bore is formed through the strata of a mine roof to allow deep insertion of an anchor therein. A support assembly passes through the bore and permits the mounting of a micrometer thereto. The lower end of the support assembly provides means for biasing a switch housing against the ceiling of the roof; As the housing moves downwardly in response to downward displacement of the roof ceiling, the micrometer actuates the switch and completes a warning circuit. Instead of the switch, a linear displacement transducer can be substituted so that as increased engagement between the micrometer and the transducer occurs, precise readings proportional to mine ceiling displacement can be made.

Description

The present invention relates to detection equipment for monitoring displacement of a mine roof.

In the past, a wide variety of instrumentation has been conceived and built for the purposes of detecting significant displacement of mine roofs indicative of a cave-in condition. By making timely observation of such roof displacement, sufficient time can be allowed for miners to escape from a mine before a catastrophic situation occurs. However, existing equipment is complicated in structure which discourages mine operators from utilizing a sufficient number to detect the formation of a dangerous condition. Certain types of available equipment require permanent installation which results in financial loss to mine operators when it is no longer necessary to monitor a section of the mine roof into which the equipment is permanently installed.

The present invention is a relatively simple assembly for detecting ominous mine roof displacement. Briefly, a deep bore is drilled into strata of the mine roof and an anchor is fastened at the far end. A support assembly passes through the bore and terminates slightly beyond the roof ceiling. A bracket is attached to the lower end of the support assembly and mounts a spring which normally urges an instrument housing into contact with the ceiling of the mine roof. A microswitch is enclosed within the housing and is secured thereto for linked displacement with the housing when the ceiling of the roof moves. The mounting bracket also includes an actuator member in the form of a micrometer that is normally spaced from the switch by a predetermined distance to form a gap. When the roof of the mine becomes downwardly displaced in excess of the predetermined gap length, an emergency situation is in the offing and due to actuation of the switch by the micrometer, a warning signal is sounded. As will be appreciated from this brief description, the mechanism is simply constructed and reliably designed to insure the safety of men working in the mine. Instead of the switch, a linear motion transducer may be substituted for terminating engagement with the micrometer. Therefore, as the position of the roof mine varies, greater engagement between the transducer and the micrometer results in a proportional electrical indication which can be translated to a meter reading. This enables precise monitoring of the mine roof condition. If at any time, removal of the instrument is desired, the support assembly is merely removed from the anchor thereby allowing the entire instrument to be freed of securement in the roof bore. Once removed, the instrument can be simply re-installed in a second formed bore at a desired location in the mine shaft.

These together with other objects and advantages which will become subsequently apparent reside in the details of construction and operation as more fully hereinafter described and claimed, reference being had to the accompanying drawings forming a part hereof, wherein like numerals refer to like parts throughout, and in which:

FIG. 1 is a view illustrating the device components installed in a mine roof bore for supporting the illustrating housing against the roof ceiling.

FIG. 2 is a bottom plan view of the instrument taken along a line 2--2 in FIG. 1.

FIG. 3 is a partial sectional view taken along a plane passing along section line 3--3 of FIG. 2 illustrating the components within the interior of the housing.

FIG. 4 is a second sectional view disclosing the components shown in FIG. 3.

FIG. 5 is a perspective view illustrating the utilization of a micrometer pair for actuating a warning switch as well as for operating a linear displacement transducer.

FIG. 6 is a view similar to FIG. 1 illustrating a modification to the support assembly of the invention.

FIG. 7 is an exploded view disclosing in detail the support cable used in the modified support assembly shown in FIG. 6.

Referring to the drawings and more particularly to FIG. 1 thereof, the instrument of the present invention is generally indicated by reference numeral 10 and serves to detect significant displacement within the lower strata of a mine roof 12. In preparing to use the present invention, a vertical bore 14 is formed through the strata to allow insertion of a support assembly 15 through the bore for anchoring an upper end of the bore by a conventional expandable anchor member 16. The anchor is positioned at a distance deep enough within the strata so that normal displacement of the roof ceiling 24 does not appreciably effect the position of the upper strata wherein the anchor 16 is located. The anchor includes a portion 18 for threadingly receiving the upper end of an elongated bolt 22 which extends downwardly through the bore. Further, the anchor 16 includes an annular flange 20 for maintaining the bolt 22 centered within the bore. As will be noted from the figure, bolt 22 extends slightly beyond ceiling 24. A housing 26 allows passage of the bolt 22 therethrough and means discussed later are provided for biasing the housing 26 against the mine ceiling 24.

In order to retain housing 26 in a stable position, tubular member 30 is attached to an upperside of housing 26 and is adapted for guided insertion within the lower portion about bore 14. As FIG. 3 clearly illustrates, the upper side 32 provides a base into which flange portions at the lower end of tube 30 can be fastened by suitable hardware 34. A countersunk aperture 36 is formed through the upper side 32 and embraces bolt 22 thereby fixing the lateral relationship between the bolt and the housing.

The lower end of bolt 22 slidably mounts a bracket 38 for mounting a micrometer 44. A thumb wheel 40 in the bracket aids in securing the bracket 38 in a particular position on bolt 22. A coil spring 42 is concentrically mounted on the lower end portion of bolt 22 and abuts the bracket 38 at one end while abutting an oppositely disposed bossed surface of the housing. It is spring 42 which biases the housing 26 into contact with ceiling 24. An opening 43 is formed in the housing to permit free passage of spring 42 therethrough.

The micrometer 44 mounted to bracket 38 serves as an actuator for a confrontingly positioned switching key 46 extending downwardly from a microswitch 48 which is positioned in the housing 26. More particularly, the microswitch 48 is pivotally mounted to the housing at one end thereof as indicated in FIG. 4. A spring 54 is positioned between the upper surface of the microswitch 48 and the upper side 32 of housing 26. The spring 54 provides an override means whereby excessive engagement between the micrometer 44 and the switch key 46 can be tolerated to an extent because the pivotal mounting will enable the microswitch to yield from its normal position. If the spring 54 and pivotal mounting of the microswitch were not furnished, excessive engagement between the micrometer and the switch key would cause mechanical failure or breakage of the micrometer, microswitch, or both.

In order to provide a voltage source for connection between the microswitch 48 and a suitable warning device, a battery 56 is included within housing 26 and as indicated in FIG. 4, an emergency signal lamp 58 mounted to the lower side of the housing 26, provides an appropriate signalling means. For purposes of convenience, connecting wires have been eliminated from the figure. However, as will be obvious, such connecting leads serially connect the battery 56, microswitch 48 and lamp 58. Of course, electrical power could be fed to the instrument instead of using a battery. In order to seal lamp 58 from corrosive atmospheric conditions, a plastic lens 62 surrounds the lamp and is sealed within the lower side of housing 26.

By referring to FIG. 3 the operation of the preferred embodiment will be explained. With the housing 26 in abutting relation with ceiling 24, a gap exists between micrometer 44 and switch key 46. The gap is adjustable so that it corresponds with the distance the ceiling would be displaced in an emergency situation. Thus, when such displacement occurs, the housing 26 is urged downwardly by the abutting ceiling surface 24.

Referring to FIG. 5, the aforementioned bracket 38 is shown with the normal mounted micrometer 44. However, if desired, a second bracket 64 identical with the bracket 38 may also be mounted upon bolt 22 and fastened thereto with thumb wheel 66. At the end of bracket 64 a second micrometer 68 identical to the first-mentioned micrometer 44 can be secured to housing 26 and positioned in normal contact with a linear displacement transducer 70. As ceiling 24 begins to move, the engagement between micrometer 68 and transducer 70 increases thereby causing continually increasing electrical output from the transducer 70. The electrical outlet can be coupled to a voltmeter type instrument for precisely indicating a measurement corresponding to ceiling displacement. The transducer is of a conventional type and can typically include a piezo-electric crystal which generates electrical output in response to increasing bearing relation with the micrometer 68. A second form of transducer can be of the type employing a linear displacement potentiometer which generates increasing electrical voltage in accordance with increased engagement between micrometer 68 and the transducer 70.

The second embodiment of the present invention is illustrated in FIG. 6 and includes substantially all the components illustrated in the previously mentioned embodiment with the exception of the support assembly 71. Thus, instead of an elongated bolt 22 passing downwardly through the major portion of bore 14, in the second embodiment illustrated in FIG. 6, a support cable performs the same function. Basically, a threaded stud 72 serves as an adapter between the upper end of the support cable 88 and the previously utilized anchor 16. In FIG. 7, the adapter is shown to include a threaded rod portion 74 that is insertable within the anchor 16, the rod terminating at a lower end in a fastening block 76. The fastening block includes a centrally disposed bore 78 passing perpendicular to the threaded rod 74. A groove 80 communicates with bore 78 and in turn communicates with a perpendicular slot 82 passing downwardly through the lower side of the block 76. A tubular member 84 includes diametrical holes 86 therein for receiving the upper end portion of cable 88. The actual end 90 is deposited in a second aperture in the tubular member and a setscrew 92 clamps the cable end 90 against the tubular member 84. When assembling the adapter, the tubular member 84 having the clamped cable therein is positioned within bore 78. Then, the tubular member 84 is rotated until the cable 88 passes through the slot 82 in block 76. An overall view of this relationship between cable and adapter is shown in FIG. 6. At the lower end portion of the bore 14, the aforementioned tubular member 30 is used and allows passage of a hollowed tubular section 94 that passes through housing 26. As will be observed in FIG. 7, the lower end of tubular member 94 is threaded at 96 for insertion within a threaded bore 100, the latter formed in block 98. The block serves to clamp the lower end of cable 88. In order to effect this clamping, the cable 88 passes through threaded bore 100 and is looped upwardly through a second bore 102 offset from the first bore 100. Then, the remaining end portion of cable 88 is looped downwardly through a third bore 106 positioned in linear spaced relation.

A final threaded bore 108 is formed perpendicularly with respect to the first mentioned threaded bore 100 and communicates with the bore 106. A setscrew 110 is received within the threaded bore 108 and clamps the end portion of cable 88 to the block 98. Thus, by clamping the cable 88 and the upper and lower ends thereof, a suitable support for housing 26 is effected. As will be noticed in FIG. 6, the housing is retained against ceiling 24 by the urging of spring 42 disposed between the housing and bracket 38. However, in the embodiment shown in FIG. 6, rather than the bracket being mounted to the lower end portion of bolt 22 (FIG. 3), it is bolted to the lower end of the tubular member 94. In operation, the embodiment illustrated in FIG. 6 functions as previously described in connection with the first embodiment.

The foregoing is considered as illustrative only of the principles of the invention. Further, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation shown and described, and accordingly all suitable modifications and equivalents may be resorted to, falling within the scope of the invention.

Claims

What is claimed as new is:

1. A displacement detecting device for mine roofs and the like comprising an elongated support member adapted for anchored reception within a roof bore, an earth engaging anchor at one end of the support member constituting the inner bore received end thereof, a bracket mounted on the second or outer end of the support member, a housing slidably mounted on the support member inward of the bracket, resilient biasing means engaged between the bracket and the housing for resiliently maintaining the housing against the roof surface, a switch mounted within said housing and including an exposed outwardly directed switch key, signal means operated by said switch, and a switch actuator mounted on said bracket and in inwardly directed aligned spaced relation to said switch key for a selective actuation of the switch upon an outward movement of the earth against which the housing is engaged for movement of the housing against the biasing force of the biasing means to engage the switch key against the actuator, said actuator being in the nature of an adjustable micrometer for selective adjustment toward and away from said switch key to vary the distance therebetween and the point of engagement therebetween.

2. The device of claim 1 wherein said housing includes an elongated guide tube fixed thereto and projecting inwardly in surrounding relation to said support member, said switch being pivotally and resiliently mounted within said housing to compensate for excessive loads introduced thereto by engagement of the actuator against the switch key.

3. The device of claim 2 including a second bracket mounted adjacent the outer end of said support member, a second actuator mounted on said second bracket, and a transducer for generating a signal proportional to linear displacement of the roof, said transducer being mounted on said housing and in engagement with the second actuator for continued movement toward the second actuator upon displacement of the housing.

4. The device of claim 3 wherein each bracket is longitudinally adjustable along said support member.

5. A displacement detecting device for mine roofs and the like comprising an elongated support member adapted for anchored reception within a roof bore, an earth engaging anchor at one end of the support member constituting the inner bore received end thereof, a bracket mounted on the second or outer end of the support member, a housing slidably mounted on the support member inward of the bracket resilient biasing means engaged between the bracket and the housing for resiliently maintaining the housing against the roof surface, a switch mounted within said housing and including an exposed outwardly directed switch key, signal means operated by said switch, and a switch actuator mounted on said bracket and in inwardly directed aligned spaced relation to said switch key for a selective actuation of the switch upon an outward movement of the earth against which the housing is engaged for movement of the housing against the biasing force of the biasing means to engage the switch key against the actuator, said switch being pivotally and resiliently mounted within said housing to compensate for excessive loads introduced thereto by engagement of the actuator against the switch key.

6. A displacement detecting device for mine roofs and the like comprising an elongated support member adapted for anchored reception within a roof bore, an earth engaging anchor at one end of the support member constituting the inner bore received end thereof, a bracket mounted on the second or outer end of the support member, a housing slidably mounted on the support member inward of the bracket, resilient biasing means engaged between the bracket and the housing for resiliently maintaining the housing against the roof surface, a switch mounted within said housing and including an exposed outwardly directed switch key, signal means operated by said switch, a switch actuator mounted on said bracket and in inwardly directed aligned spaced relation to said switch key for a selective actuation of the switch upon an outward movement of the earth against which the housing is engaged for movement of the housing against the biasing force of the biasing means to engage the switch key against the actuator, a second bracket mounted adjacent the outer end of said support member, a second actuator mounted on said second bracket, and a transducer for generating a signal proportional to linear displacement of the roof, said transducer being mounted on said housing and in engagement with the second actuator for continued movement toward the second actuator upon displacement of the housing.

7. A displacement detecting device for mine roofs and the like comprising an elongated support member adapted for anchored reception within a roof bore, an earth engaging anchor at one end of the support member constituting the inner bore received end thereof, a bracket mounted on the second or outer end of the support member, a housing slidably mounted on the support member inward of the bracket, resilient biasing means engaged between the bracket and the housing for resiliently maintaining the housing against the roof surface, a switch mounted within said housing and including an exposed outwardly directed switch key, signal means operated by said switch, and a switch actuator mounted on said bracket and in inwardly directed aligned spaced relation to said switch key for a selective actuation of the switch upon an outward movement of the earth against which the housing is engaged for movement of the housing against the biasing force of the biasing means to engage the switch key against the actuator, said bracket being adjustable longitudinally along said support member, and means for selectively locking said bracket in any adjusted position thereout.