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BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to a drilling apparatus. 
     2. Discussion of the Prior Art 
     Currently available diamond drilling rigs are usually large, heavy assemblies, which are susceptible to movement during drilling. Such rigs, which are intended to deep well drilling (2000-3000 feet) include a derrick mounted on a platform fur supporting the remaining elements of the rig. During drilling on soft ground, the reaction between the drill string and the derrick tends to push the platform upwardly. When pulling the drill string upwardly, the platform tends to sink into the ground. In either case, the derrick and consequently the drill string can become misaligned with the borehole or well. 
     GENERAL DESCRIPTION OF THE INVENTION 
     An object of the present invention is to provide a solution to the above-identified problem in the form of a relatively simple, portable drilling apparatus which can be anchored to the bedrock during drilling or core sample removal, and consequently cannot become misaligned due to reaction forces between the drill and the rock. 
     Another object of the invention is to provide a lightweight, modular drilling apparatus, which is easy to assemble and disassemble. A lightweight modular apparatus of the type described herein is air portable. The elements of the apparatus can be delivered in the order in which they are to be assembled by helicopter to a drilling site where the apparatus is quickly put together in a matter of hours. Upon completion of a drilling operation, the process is reversed, and the elements of the apparatus can be expeditiously removed from the drilling site. There is no need for a large heavy derrick, which cannot be assembled and disassembled in a short time. 
     Accordingly, the invention relates specifically to a drilling apparatus for use with a well casing anchored in the ground at the start of a drilling operation, and a platform for positioning at a drilling site, said apparatus comprising: 
     (a) a mast for mounting on said platform for rotation between a horizontal use position and an inclined or vertical drilling position; 
     (b) a rod clamp fixedly mounted on one end of said mast for clamping a drill rod during a drilling operation; 
     (c) a casing clamp on said one end of said mast for clamping said mast to a top end of said casing, whereby the mast is anchored to the ground during drilling operation; 
     (d) a drill head slidably mounted on said mast for movement toward and away from said rod clamp, said drill head being adapted to drive a drill rod during a drilling operation; and 
     (e) a main ram connected to said mast and said drill head for moving said drill head longitudinally of the mast during a drilling operation. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention is described below in greater detail with reference to the accompanying drawings, which illustrate a preferred embodiment of the invention and wherein: 
     FIG. 1 is a side view of a drilling apparatus in accordance with the invention; 
     FIG. 2 is a side view on a larger scale of one end of the apparatus of FIG. 1; 
     FIG. 3 is a partly sectioned, perspective view of a mast, saddle and carriage used in the apparatus of FIGS. 1 and 2; 
     FIG. 4 is an exploded isometric view of a track and saddle retainer used in the apparatus of FIGS. 1 and 2; 
     FIG. 5 is a cross section taken generally along line  5 — 5  of FIG. 2; 
     FIG. 6 is a perspective view of the carriage of FIG. 3 as seen from below; 
     FIG. 7 is a longitudinal sectional view of a main ram used in the apparatus of FIGS. 1 and 2; 
     FIG. 8 is a plan view of one end of an auxiliary ram used in the apparatus of FIGS. 1 and 2; 
     FIG. 9 is an exploded perspective view of a bracket used to connect the auxiliary ram to a rod clamp; 
     FIG. 10 is a perspective view of the rod clamp and a casing clamp used in the apparatus of FIGS. 1 and 2; 
     FIG. 11 is a cross section of one-half of the casing clamp of FIG. 10 taken generally along line  11 — 11  of FIG. 10; and 
     FIG. 12 is an schematic side view of the apparatus of FIGS. 1 and 2 during a drilling operation. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to FIGS. 1 and 2, the basic elements of the drilling apparatus include an elongated mast  1  for slidably supporting a drill head  2 , a rod clamp  3  mounted on one end  4  of the mast  1 , and a casing clamp  5  for securing the mast and consequently the remainder of the apparatus to the top end of a well casing  6  (FIGS.  1  and  3 ). 
     The mast  1  is pivotally mounted on a post  8  at one end of a platform  9  for rotation between a rest position (FIG. 1) and a vertical position (not shown). In the rest position, the mast  1  is supported by a cradle  10  at the other end of the platform  9 . The mast  1  is raised using a hydraulic ram  11 , the bottom end of which is pivotally connected to a crossbar (not shown) in the platform  9 . The top end of a piston rod  12  extending out of the cylinder is pivotally connected to one of two devises  13  on the bottom of the mast  1 . One clevis  13  is used to raise the mast  1  through 45° and the over clevis  13  (on the left in FIG. 1) is used to raise the mast  1  to the vertical position. 
     The drill head  2  is carried by a saddle  14  which is moved longitudinally of the mast  1  by a hydraulic ram generally indicated at  15  (FIG.  5 ), which is described Kit hereinafter in greater detail. As best shown in FIGS. 3,  5  and  6 , the saddle  14  is generally C-shaped in cross section, including a planar top wall  16 , inclined  20  shoulders  17  and straight side walls  18 . The top wall  16  of the saddle  14  rides on the top wall  19  of the mast  1 , and the shoulders  17  ride on tracks  20  of the V-shaped cross section welded to the sides  21  of the mast  1 . 
     Slides  22  defined by strips of ultra high molecular weight polyethylene (UHMWPE) are connected to the interior surfaces of the top wall  16  and the shoulders  17  of the saddle, and to the inclined top surface of a saddle retainer  23  (FIG. 4) to facilitate sliding. The saddle  14  is retained on the mast by bolts  24  extending through lugs  25  and  26  on the edges of the shoulders  17  and on the outer surfaces of the retainer  23 , respectively and nuts  27  (FIG.  4 ). 
     The saddle  14  is connected to a carriage generally indicated at  28  which is moved longitudinally in the mast  1  by the hydraulic ram  15 . 
     The carriage  28  is also generally C-shaped in cross section, including a top wall  29  and side walls  30 . UHMWPE strips  31  (FIG. 5) mounted on the interior of the sides  21  of the mast  1  center the carriage  28  in the mast. Rollers  32  are mounted in recesses  33  in the ends of each side wall  30  of the carriage  28  for riding on the sides  21  of the mast  1 . A rectangular cross section projection  34  extends along the length of the top wall  29  of the carriage  28 . The projection  34  extends through an elongated slot  35  in the top wall  19  of the mast  1 . Transversely extending notches  36  in the protection  34  receive transversely extending ribs  37  on the bottom of a rectangular spacer  38 . The spacer  38  spaces the saddle  14  from the mast  1 . A cylindrical post  39  on the top of the spacer  38  extends through the slot  35  in the mast hole  41  (FIG. 5) in a reinforcing plate  42 , respectively welded to the top wall of the carriage. The post  39  helps to center the saddle  14  on the mast  1  during assembly. A plurality of bolts  43  extend through the reinforcing plate  42 , the top wall  16  of the saddle  14  and the spacer  38  into the projection  34  and the top wall  29  of the carriage  28  to securely connect the saddle  14  to the carriage  28 . 
     As mentioned above, the carriage  28  and consequently the saddle  14  and the drill head  2  carried thereby are moved longitudinally of the mast  1  by a main ram  15  which includes a cylinder  44  with a cap  45  on one end thereof carrying a hollow, generally cylindrical rod  46 . 
     The other, internally threaded end  48  of the cylinder  44  is closed around the rod  46  by a sleeve  50  carrying a wiper  51 , a high pressure seal  52  and an O-ring  53 . The interior of the sleeve  50  is brass lined to facilitate sliding of the rod  46  therein. A pair of diametrically opposed, cylindrical trunnions  55  are used to connect the cylinder to the carriage  28 . As shown in FIGS. 3 and 5, the trunnions  55  extend into swivel bushings  56  mounted in blocks  57 , which slide in recesses  58  in the inside of the side walls  30  of the carriage  28 . The swivel bushings  56  permit vertical movement of floating of the end  48  of the cylinder  44 . 
     The threaded outer end  60  of the hollow rod  46  is closed by a manifold  61 . Ports  62  and  63  in the manifold  61  introduce and vent hydraulic fluid from the end of the rod  46 . A pair of holes  65  in the manifold  61  receive pins (not shown) for connecting the free outer end  60  of the rod  46  to the mast  1 . Thus, when fluid is introduced into one of the ports  62  or  63  and discharged through the other, the cylinder  44  and consequently the carriage  28  are caused to move longitudinally of the mast  1 . Movement of the carriage  28  is accompanied by sliding of the saddle  14  and the drill head  2  mounted thereon. When fluid is introduced through the port  62 , it flows through a tube  66  in the piston rod  49  into a chamber  67  between the cap  45  and an aluminum sleeve  68  defining a piston head. The tube  66  is supported at one end by a sleeve  69  sealed in the port  62  by an O-ring  70  and at the larger diameter other end  71  by the rod  46 . A steel ring  72  sandwiched between the sleeve  68  and a shoulder  73  on the piston rod  46  acts as a bearing surface for the piston  68 . The sleeve  68  is sealed with respect to the piston rod  49  by an O-ring  74 , and with respect to the cylinder  44  by a high pressure seal  75 . Wear sleeves  76  are provided in the piston head. 
     When fluid is introduced into the port  63 , it flows through a passage  77  between the interior of the rod  46  and the exterior of the tube  66  and then through radially extending holes  78  in the piston rod  49  into a chamber  80  between the sleeve  50  and the sleeve  68 . 
     The cylinder  44  is caused to move in the opposite direction expelling fluid from the chamber  67  through the tube  66  and the port  62  in the manifold  61 . Because the outer end of the piston  46  is fixed in the mast  1 , the cylinder  44  is caused to move in the opposite direction (to the left in FIG.  7 ), causing a corresponding movement of the carriage  28 , the saddle  14  and the drill head  2 . 
     The conventional drill head  2  is used to rotate a drill rod  82  (FIG. 12) during the addition or removal of drill rod sections, or during a drilling operation. A suitable drill head  2  includes a 12HH underground chuck  83 , a B15 or B15 gear box  84  and a drive tube  85  (all available from J. K. S. Boyles, North Bay, Ontario), and a hydraulic motor  86 . The saddle  14 , the carriage  28  and the main ram  15  are used to move/the drill head  2  and the drill rod  82  relative to the mast  1  during drilling or when removing the drill rod  82  from the ground. 
     A conventional rod clamp  3  of the type available from J. K. S. Boyles, North Bay, Ontario is used to clamp the drill rod  82  during the addition or removal of drill rod sections. It will be appreciated that the rod clamp  3  holds a first drill rod section stationary while a second section is rotated by the drill head  2  to attach the second section to the first section or detach the second section from the first section. The rod clamp  3  is securely mounted on one end of the mast  1  (the bottom end during drilling downwardly). 
     In order to balance the forces on the apparatus, an optional auxiliary ram  90  extends between the drill head  2  and the rod clamp  3 . The auxiliary ram  90 , which is parallel to the main ram  15 , includes a hydraulic cylinder  91  mounted on the rod clamp  3 . The free end  93  of a piston rod  94  extending out of the cylinder  91  connected to a bracket  96  on the top of the drill head  2  by a spherical bearing  97 . The bearing  97  is mounted on a rod  98  extending through sleeves  99  welded to the sides  100  of the bracket  96 . The rod  98  is held in the bracket  96  by cotter pins  101  (FIGS.  2  and  7 ). When the main ram  15  is actuated during a rod pulling operation, the auxiliary ram  90 , which is parallel and spaced apart from the ram  15 ,is also actuated to balance the forces acting on the apparatus. A bracket generally indicated at  103  connects the cylinder  91  to the rod clamp  3  and permits limited pivoting of the auxiliary ram  90  around two axes, which are perpendicular to each other. For such purpose, the bracket  103  includes a baseplate  105  (FIGS. 9 and 10) connected to the rod clamp  3  by two end plates  106 . A post  107  (FIG. 9) extends upwardly from the center of the base plate  105 , and a swivel plate  109  is rotatably mounted on the post  107  between corner posts  110 . There is clearance between the notched corners  111  of the swivel plate  109  and the posts  110  permitting limited rotation of the swivel plate  109  around the axis of the center post  107 . The swivel plate  109  is retained on the baseplate  105  by a pair of crossbars  113 , bolts  114  and nuts  115 . A pair of posts  117  reinforced by gussets  118  extend upwardly from the sides of the swivel plate  109 . Bearings  120  in the posts  114  rotatably support trunnions  121  extending outwardly from a band  122  extending around the cylinder  91 . Thus, limited rotation of the auxiliary ram  90  around two axes perpendicular to the longitudinal axis of the rod clamp  3  is possible to compensate for any misalignment between the axis of the feed cylinder  14  and the auxiliary ram  90 . 
     As mentioned above, during a drilling operation the top end of a well casing  6  is secured to the mast  1  by a casing clamp  5 . With reference to FIGS. 10 and 11, the casing clamp  5  includes a pair of arms  124  pivotally connected to the outer or bottom end of the rod clamp  3  by hinges  125 . A jaw  126  is provided on the outer end of each arm  124 . The jaws  126  are defined by rectangular parallelepipedic, metal blocks containing opposed, longitudinally extending, semicylindrical troughs  128 . When the jaws  126  are bolted together using bolts  127  and nuts (not shown) the troughs  128  define a cylindrical passage for receiving the top end of the well casing  6 . Toothed carbide inserts  129  (FIG. 11) in the troughs  128  firmly engage the casing  6  preventing relative movement between the jaws  126  and the casing  6 . 
     Referring to FIG. 12 as mentioned hereinbefore, if a remote drilling site has been chosen, the components of the drilling apparatus are carried to the site by helicopter in the order in which they are to be assembled. At the site, a platform  131  is constructed to support the apparatus of the present invention. The top  132  of the platform  131  is as level, i.e. as close to the horizontal as possible. 
     With the apparatus in position, the first step in the drilling process is to drill a hole in the ground  134 . The hole is drilled into the bedrock  135  using an anchor rod  137 . The rod  137  is burned in, i.e. drilled into the ground without water coolant until the bottom end of the rod melts into a ball at the bottom becoming one with the bedrock  135 . A chain  138  is used to connect the top end of the rod  137  to the mast  1 , and is tightened using a chain binder (not shown). The casing  6  is then drilled into the ground  134  until it also enters the bedrock  135 . 
     A drill rod  82  is inserted into the drill head  2  passing through the rod clamp  3 . Downward pressure on the drill rod  82  is exerted to tension the mast  1  and the rod clamp  3  with respect to the well casing  6 . The casing clamp  5  is then closed on the upper end of the casing  6 , i.e. the jaws  126  are bolted together. The result is a unitary structure defined by the mast  1 , components on the mast  1 , the well casing  6  and the anchor rod  137 . With such a structure, drilling can be effected with relative little, if any movement of the platform  9 . Any reaction forces generated during drilling or rod pulling are absorbed by the casing  6  and the anchor rod  137 . During rod pulling or pull back, any forces are supported by the casing  6  via the clamp  5 . Thus, the mast  1  cannot move and the platform  9  remains stationary, even on soft ground.

Summary:
A drilling apparatus includes a platform for positioning at a drilling site) a mast pivotally mounted on the platform) a rod clamp on one end of the mast for clamping a drill rod) a drill head slidably mounted on the mast for driving the drill rod during a drilling operation, a main ram connected to said mast and said drill head for moving the drill head longitudinally of the mast) a casing clamp on the rod clamp for clamping the mast to a top end of a casing carrying the rod) whereby the mast is anchored to the ground during drilling) and a drill head slidable on the mast for driving the drill rod during drilling.