| 摘要 |
The apparatus comprises a mine shaft roof bolting machine for drilling holes in a mine shaft roof in combination with an apparatus for controlling the thrust applied to the drill rod, commonly known as a pinning rod, to ensure that a buckling failure of the pinning rod will not occur. The thrust is controlled by a computer in conjunction with a solenoid controlled relief valve which is actuated by commands from the computer. The computer determines the length of the pinning rod exposed below the mine shaft roof from data received from one or more of the following sensors: an electronic device for measuring hydraulic cylinder rod extension, contact switches, rotary encoders, proximity switches, and ultrasonic transceivers and associated circuitry. From these data it calculates the maximum thrust which can be applied to the pinning rod without causing a buckling failure of the pinning rod and controls the maximum thrust delivered to the rod through the computer actuated pressure control valve to maintain the thrust at or below the maximum thrust. As a backup safety device the apparatus also includes provisions to use data read by the computer from load cells or strain gages attached to the torque motor, its housing, or other support means, to detect the moment applied to the motor shaft whenever the pinning rod begins to bend at the onset of buckling.
|
