Drill rig

In a preferred embodiment the core drilling rig of the present invention includes a base, a vertically extending mast, a movable carriage mounted on the mast, an electric powered motor for rotatably driving a core drill bit, and a control system for controlling the supply of electric power to the drive motor. The control system includes a motion sensitive device for detecting the unwanted movement of the base and suspending the supply of electric power to the motor.

FIELD OF INVENTION 
The invention concerns a portable drill rig for supporting and driving for 
rotation a core drill bit for use in drilling openings in concrete and 
related materials. More particularly, the present invention concerns a 
drill rig for use in core drilling that includes a control system for 
suspending the operation of the rig upon sensing undesirable motion of the 
rig's base. 
BACKGROUND 
Drill rigs for use in core drilling concrete, masonry, stone and similar 
materials are well-known in the prior art. An example of a prior art core 
drilling rig is a rig manufactured by Diamond Products of Elyria, Ohio, 
which is sold under the trade designation "M-2." 
Generally, prior art core drill rigs comprise a base, a vertically 
extending mast, a movable carriage mounted on the mast and an electric 
powered motor for rotatably driving a core bit. The base usually includes 
some type of means for securing the rig to the surface of the material 
that is being drilled. For example, the base may include a vacuum system 
or a mechanical anchoring system that allows the rig to be temporarily 
attached to the surface that is being drilled. 
No matter what type of means are used to secure the core drilling rig, it 
is very important that the rig be secured. More particularly, core 
drilling tends to require a significant amount of torque, and if the base 
is not securely attached, the base can become free and the entire rig can 
begin rotating about the core drill bit thereby creating a dangerous 
condition. 
SUMMARY OF INVENTION 
The present invention provides a new and improved core drill rig that 
provides a significant added degree of safety during operation. More 
particularly, the drill rig of the present invention automatically 
discontinues operation upon the occurrence of any undesirable movement or 
motion of the rig's base. 
In a preferred embodiment the core drilling rig of the present invention 
includes a base, a vertically extending mast, a movable carriage mounted 
on the mast, an electric powered motor for rotatably driving a core drill 
bit, and a control system for controlling the supply of electric power to 
the drive motor. The control system includes a motion sensitive device for 
detecting the unwanted movement of the base and suspending the supply of 
electric power to the motor. 
The foregoing and other features of the invention are hereinafter more 
fully described and particularly pointed out in the claims, the following 
description setting forth in detail certain illustrative embodiments of 
the invention, these being indicative, however, of but a few of the 
various ways in which the principles of the present invention may be 
employed.

DETAILED DESCRIPTION 
Referring to the drawings, and initially to FIG. 1 there is illustrated a 
core drilling rig 10 made in accordance with the present invention. Rig 10 
is intended for use in core drilling concrete, masonry, stone, rock and 
similar materials. 
As shown in FIG. 1, drill rig 10 includes various features that are common 
to prior art drilling rigs. More particularly, rig 10 includes a base 12, 
a vertically extending mast 14, a carriage 16 that is movable along the 
mast 14, and an electric drive motor 20 that is mounted to the carriage 
16. Motor 20 serves to rotatably drive a conventional core bit 24 such as, 
for example, a diamond core bit sold by Diamond Products of Elyria, Ohio, 
under the registered trademark CORE BORE. By use of a rack 26 mounted on 
mast 14 and a pinion gear 28 (shown by hidden lines) the carriage 16 is 
moved along mast 14 by rotating lever 30 that is connected to the pinion 
gear 28. The base 12 of the rig 10 includes leveling screws 29, a vacuum 
system 31 to assist in the secure mounting of the base 12 to the surface 
of the material that is being drilled and a set of wheels 32 to facilitate 
the movement of the rig. Mounted on the carriage 16 is an electrical box 
33 having a panel 34. Box 33 includes an electrical hook-up 35 and 
switches 36 for manually controlling the supply of electric power to motor 
20 and the vacuum system 32. 
The feature that distinguishes rig 10 from prior art drill rigs is that rig 
10 includes a control system that automatically suspends the supply of 
electric power to the motor 20 upon undesirable motion of the base 12. The 
control system includes a motion sensitive device 40 for sensing the 
undesirable or unwanted motion of the base 12. Undesirable motion may be 
defined as the rotation of the base 12 about the bit 24. Alternatively, 
undesirable motion may be defined as the movement of the base 12 in any 
direction relative to the surface that is being drilled in excess of about 
0.25 inches. 
Referring additionally to FIG. 2 the details of the control system will be 
better understood. More particularly, as shown in FIG. 2 the control 
system is integrated into the electric circuit which supplies power to the 
motor 20 from the electrical source 44 (for example a 120 or 240 VAC power 
source). The system includes the motion sensitive device 40 which is 
preferably connected to a relay 48 having a reset switch 50. Upon sensing 
undesirable motion of the base 12 the device 40 triggers the relay 48 
thereby suspending the supply of electric power to the motor 20. The 
switch of relay 48 is reset by reset switch 50 thereby allowing motor 20 
to operate until acceleration sensitive device 40 triggers relay 48 open 
once again. Motion sensitive device 40 and relay drive 48 are preferably 
mounted within box 33 and reset switch 50 is preferably mounted on panel 
34. It will be appreciated that the control system could include a 
"plugging" circuit that momentarily reverses the supply of current to 
motor 20 thereby helping to quickly suspend the turning or rotation of the 
motor. 
As shown in FIG. 1, motion sensitive device 40 is preferably mounted on or 
in the electrical box 33 of the rig. However, it will be appreciated that 
the device 40 may be mounted on other portions of the rig. The box 33 is a 
preferred location for device 40 since no additional external wiring is 
required with this type of mounting. Such external wiring could be damaged 
or tampered with. However, it will be appreciated that other mounting 
locations are possible, such as, for example, on the base 12. 
Relative to the issue of providing a control system for suspending the 
supply of electric power to a motor upon the occurrence of unwanted 
motion, a core drill rig represents a major challenge as compared to other 
related tools or equipment. More particularly, because a considerable 
amount of normal vibration and movement is experienced during core 
drilling, many sensors such as contact switches are not effective. Also, 
in many environments where core drill rigs are employed, a contact switch 
will not survive the dust and dirt found in such environments. As to kill 
switches that require constant engagement by an operator, such switches 
are easily defeated or disabled by an operator. Quite unexpectedly, 
however, acceleration sensitive devices have been found to be very useful 
in the present invention. 
Acceleration sensitive devices are capable of sensing motion and 
acceleration. Such devices may be mounted at various locations on the rig 
and are not limited to being mounted, for example, on the base. 
Acceleration sensitive devices are available from various sources 
including Inertia Switch Incorporated of West Nyack, N.Y. 10994. Such 
switches are generally the spring-mass type or the magnetic type. These 
devices are available in various sensing capacities such as unidirectional 
(sensitivity in one direction), bidirectional (sensitivity in two 
directions), planar directional (sensitivity in a given plane), 
hemispherical (sensitive to motion in a given hemisphere) and 
omnidirectional (sensitivity in any direction). These devices may also be 
damped. Damping allows the device to disregard usual conditions of 
vibration or shock. 
Whatever acceleration sensitive device is utilized, the device should have 
a sensitivity of at least about 0.05 g's. Having too low of a sensitivity 
is a problem because it can lead to the suspension of power to the motor 
20 as a result of normal vibration or motion during the drilling 
operation. 
A preferred acceleration sensitive device for use in the present invention 
is a radial motion/inertia switch sold by Inertia Switch Incorporated 
under the trade designation 4RO-126. This particular device is capable of 
sensing acceleration as low as about 0.1 g's. 
It will be appreciated that although an acceleration sensitive device is 
preferred, it may be possible to utilize other devices, such as, for 
example, proximity sensors, mass sensors, electric eyes and similar 
devices as the motion sensitive device in order to provide the benefits of 
the present invention. 
While the invention has been explained in relation to its preferred 
embodiments, it is to be understood that various modifications thereof 
will become apparent to those skilled in the art upon reading the 
specification. Therefore, it is to be understood that the invention 
disclosed herein is intended to cover such modifications as fall within 
the scope of the appended claims.