US2039520A - Core drill - Google Patents

Description

May 5, 1936. 5. COPELIN 7 2,039,520

coma DRILL Filed March 4, 1935 A9 37 26 37 24 INVENTOR I 1.5.Cope/fr7 v ATTORNEY.

Patented May 5, 1936 UNITED STATES PATENT OFFICE 7 Claims.

This invention relates generally to rotary core drills such as are commonly used in earth-boring operations. More particularly, the invention relates to the construction of so-called core catchers, which are employed to sever and hold a core while the drill is being raised after a drilling operation.

It is an object of the invention to provide an improved core catcher for use in conjunction with various types of core drills, with which an operator may be assured of reliable operation at all times.

Additional objects of the invention can be outlined briefly as fol1ows:To afford a simple but rugged. construction which can be readily repaired when worn through usage; to afford a self-cleaning action and thus avoid inoperativeness through fouling; to afford a type of spring action tending to keep the core centered with respect to the core passage or core barrel; to minimize blocking or breaking up of the core, which is frequently experienced with prior devices; and to afford a construction applicable equally to both hard and soft formations.

Further objects of the invention will appear from the following description in which the preferred embodiment of the invention has been set forth in detail in conjunction with the accompanying drawing.

Referring to the drawing:

Fig. 1 is a side elevational view, in cross-section, illustrating a core drillincorporatingthe present invention.

Fig. 2 is a cross-sectional detail, taken along the line 22 of Fig. 1.

Fig. 3 is a detailin plan, showing the core catcher removed from the drill of- Fig. 1.

Fig. 4 is a detail showing one of the core-engaging dogs in a retracted position.

Referring to Fig. 1, the core drill illustrated consists of an outer barrel Ill, to the lower end of which is secured a cutting head ll. The cutting head is provided with an opening l2, concentric with the axis of rotation, which serves to accommodate a core. Extending upwardly from the cutting head II and within the outer barrel In, there is an inner core barrel or retainer l3. My

improved core catcher, which in this instance is made as a separate assembly unit, is indicated generally by numeral 14. As is customary, ,provision is made for circulating lubricating mud, the mud in this instance being forced down through the passage l6 between the outer and inner core barrels, to be delivered through the passages ll of the cutting head.

The construction of the core catcher assembly 14 can be best understood by reference to Figs. 2 to 4 inclusive. It includes a plurality of dogs Ho. and"! lb, carried by a suitable collar l8. Each dog is provided with a pointed end l9, to enable it to dig into a core. To afford the desired type of action, the dogs are pivotally mounted with respect to the collar H3. Thus, for the mounting of each dog the collar i8 is cut away to afford an inclined slot 2|, and a hole is drilled through the 10 side marginsof this slot to accommodate a pivot pin 22. The upper end of pin 22 may terminate Within a notch 23, while the lower end can terminate within the confines of a bevelled surface 24 formed on the lower outer edge portion of the 1 collar. in this connection it is desirable that the lower extension of the hole accommodating the pin 22, below the lower end of this pin, be somewhat smaller in diameter, to afford a shoulder against which the lower end of pin 22 may rest, thus avoiding dropping out of the pivot pins when the core catcher is disassembled with respect to the drill.

In conjunction with the pivotal mountings, suitable springs are provided to urge the pointed ends of the dogs inwardly and downwardly. Thus, as shown in Fig. 4, each dog can be provided with a slot 26, to accommodate a coiled wire spring 21 about pivot pin 22. One end 28 of this spring can be secured to the collar, with the other end 30 bearing upon one face of the dog.

A suitable manner of incorporating the core catcher assembly into a core drill is illustrated in Fig. 1. In this case the cutting head II is provided with an inner annular recess 3|, within which the collar l8 can be seated. The lower end portion 32 of the drill body 33 affords an annular shoulder 34 overlying the upper end of the collar. When so positioned, the core catcher is in close proximity to the lower cutting end of the drill, and it surrounds the general core passage formed by the opening l2 and the core-accommodating space 35 in the inner barrel l3.

The inclination of the pivotal mountings for the dogs can now be described in greater detail.

ot pins 22 extends generally tangentially with respect to the inner and outer peripheries of collar l8 and with respect to the periphery of the core being acted upon. A further point to note is that, as will be evident from inspecting Figs. 1 and 2, the core-engaging ends l9 of the dogs swing upwardly with respect to the lower end of the drill, and backwardly with respect to the normal direction of rotation of the drill, when retracted against the urge of the springs 21. In this connection it should be noted that suitable means is employed for limiting inward and downward swinging movement of the dogs under the urge of spring 21. For example, the shoulders 31 on the collar I8 can serve as limiting stops for engagement with the dogs, whereby when the dogs are in engagement with these shoulders they extend in a generally radial direction, as shown in Fig. 3.

While the shaping and proportioning of the dogs may vary in practice, I have found it desirable to form the faces 38 somewhat concave, as appears more clearly in Fig. 2. Likewise, to insure proper action on both hard and relatively soft formations, I have formed the dogs to different lengths, as for example, with the dogs Ila longer than the dogs l'lb. Short dogs can be more readily forced into hard formations, while longer dogs afford more support for a softer core.

Operation of the device can be briefly outlined as followsz-When the drill is not in use the dogs are extended inwardly by springs 27, substantially as shown in Fig. 3. As a drilling operation is commenced, the core advances through opening I2 and into contact with the dogs. Upward pressure on the dogs, combined with a force component in a rotary direction, causes the dogs to swing back to their retracted positions (Fig. 2). While retracted, the ends is are being pressed against the core, to tend to center the core with respect to opening I2 and passage 36. When it is desired to lift the core, rotation is arrested, and the drill raised. Thereupon the dogs immediately dig into the core, with a downward and inward movement of the pointed ends Hi, to sever the core from the bottom formation and to serve as a support for the severed core during raising of the drill. Some operators may prefer to rotate the drill back- Wardly for a few revolutions before it is raised, in order to insure severing of the core, but in general this is unnecessary.

Since pivotal movement of the dogs is influenced by both vertical and rotary force components (due to the inclination of their pivotal mountings), the action of the dogs upon the core is made more positive and reliable. As long as the drill is in forward rotation, the rotary force component on the dogs will suffice to avoid premature digging into the core, even though such rotation is not accompanied by downward movement of the drill. This will be true even though the collar [8 may be loosely mounted with respect to the cutting head, since in such event a rotary force component will exist to act upon the dogs, by virtue of friction between the collar and the drill. As distinguished from such action, if the dogs were mounted upon horizontal pivotal axis, they would tend to dig into the core when rotation of the drill was not accompanied by downward movement, and thus premature severing or breaking of the core would result.

Aside from the characteristics pointed out above, it is evident that a simple but rugged construction is afforded. The dogs can be readily removed for replacement or repair, by removing the assembly from the drill, followed by removal of the pivot pins 22. Because of the pivotal movement and strong spring action afforded, the dogs will not become inoperative through fouling, and will automatically clear themselves of accumulated mud, sand or cuttings. Blocking or breaking up of the core is minimized because of better control of the dogs. as previously described, and because of proper centering of the core as it advances into the drill. Therefore, in general, the present invention is far superior to devices previously employed, and the features of superiority are obtained with a structure of utmost simplicity.

It is evident that one may deviate from the particular form of the invention illustrated in the drawing. For example, in some instances it may be desirable to employ a second core catcher, located at an elevation above the cutting head. When the advantages of a removable assembly are not desired, the dogs may be pivotally mounted upon a part of the cutting head instead of upon the removable collar I8.

While the drill described is to be taken as representative of various drills of the rotary core type, the particular cutting head shown is being made the subject-matter of a separate application.

I claim:

1. In combination with a rotary earth-boring drill of the core type, a core catcher comprising a plurality of spaced dogs, said dogs having ends adapted to dig into a core formation, means for pivotally mounting said dogs whereby each dog normally extends upwardly with respect to the cutting end of the drill and backwardly with respect to the direction of rotation while the drill is operating upon a formation, and spring means for urging each dog inwardly against a core.

2. In combination with a rotary earth-boring drill of the core type, in which a core passage extends upwardly from the cutting end of the drill, a core catcher comprising a plurality of dogs, said dogs having ends adapted to dig into a core formation, means for pivotally mounting said dogs at circumferentially spaced positions about the core passage, the axes of said pivotal mountings being generally tangential to the periphery of the core passage and being inclined at acute angles with respect to a plane normal to the axis of rotation of the drill, and spring means for urging said dogs inwardly upon a core formation.

3. In combination with a rotary earth-boring drill of the core type, in which a core-receiving passage extends upwardly from the cutting end of the drill concentric with the axis of rotation of the drill, a core catcher comprising a plurality of dogs, said dogs having pointed ends adapted to engage into a core formation, means for pivotally mounting said dogs at circumferentially spaced positions about said core passage, the axes of said pivotal mountings being generally tangential to the periphery of the core passage and being inclined at acute angles with respect to a plane normal to the axis of rotation of the drill, and a spring associated .with each of the dogs serving to urge the pointed ends of the same inwardly and downwardly.

4. In combination with a rotary earth-boring drill of the core type, in which a core-receiving passage extends upwardly from the cutting end of the drill concentric with the axis of rotation, a core catcher comprising a plurality of dogs, each of said dogs having an end adapted to dig into a core formation, means for pivotally mounting the other end of each of said dogs at circumferentially spaced positions about the core passage, the axes of said pivotal mountings being generally tangential to the periphery of the core passage and being inclined at acute angles with respect to a plane normal to the axis of rotation of the drill, and spring means associated with said dogs serving to normally urge the same to swing inwardly into said core passage and downwardly towards the cutting end of the drill, said dogs when engaging a core during a drilling operation having their core-engaging ends directed backwardly with respect to the direction of rotation of the drill.

5. In combination with a rotary earth-boring drill of the core type, in which a core passage extends upwardly from the cutting end of the drill concentric with the axis of rotation of the drill, a core catcher comprising a plurality of dogs, one end of each of said dogs being pointed for digging into a core formation, means for pivotally mounting the other ends of the dogs at circumferentially spaced positions about the core passage, the axes of 'said pivotal mountings being generally tangential to the periphery of the core passage and being inclined at acute angles with respect to a plane normal to the axis of rotation of the drill, and a spring associated with each of the dogs tending to swing the core-engaging ends of the same inwardly and downwardly, the inner faces of the dogs being concave.

6. In combination with a rotary earth-boring drill of the core type, in which a core passage extends upwardly from the cutting end of the drill concentric with the axis of rotation of the drill, a core catcher comprising a collar adapted to be carried by the drill and surrounding said passage, a plurality of dogs, each of said dogs having an end adapted to dig into a core, means for pivotally mounting said dogs at circumferentially spaced points on said collar, the axes of said pivotal mountings being generally tangential to the inner and outer peripheries of the collar and being inclined at acute angles with respect to a plane normal to the axis of rotation of the drill, and springs carried by the collar serving to urge the core-engaging ends of the dogs inwardly and downwardly, said collar affording stops for arresting such swinging movement at limiting positions in which the dogs extend substantially radially with respect to the axis of rotation.

7. In combination with a rotary earth-boring drill of the core type, in which a core passage extends upwardly from the cutting end of the drill concentric with the axis of rotation of the drill, a core catcher comprising a collar adapted to 'be seated within the drill to surround the core passage, a plurality of dogs, each of said dogshaving a pointed end adapted to dig into a core, the collar having slots formed therein for receiving the dogs, pins carried by the collar for pivotally carrying theother ends of the dogs, said pins extending substantially tangentially to the inner and outer peripheries of the collar and being inclined at acute angles with respect to a plane normal to the axis of rotation of the drill, springs carried by the collar and serving to urge the dogs about said pivot pins, whereby the core-engaging ends of said dogs are urged inwardly into the core passage and downwardly towards the cutting end of the drill, said dogs when retracted with respect to said core passage having their core-engaging ends extending rearwardly with respect to the direction of rotation of the drill, and means formed on the collar for limiting inward and downward pivotal movement of the dogs.

LEONARD S. COPELIN.

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