GB2152100A - Vibratory drill apparatus - Google Patents

Abstract

A vibratory, core drill apparatus comprises a housing (2) and an eccentric member rotatably mounted in the housing for vibrating the apparatus when the eccentric member is rotated about an axis of rotation. There is one coupling for connecting a rotating power source (14) to the eccentric member to rotate the eccentric member and another coupling for connecting to the housing a core drill stem (52) with a longitudinal axis so the longitudinal axis is perpendicular to the axis of rotation of the eccentric member. <IMAGE>

Description

SPECIFICATION Vibratory drill apparatus This invention relates to a vibratory, core drill apparatus.

Core samplings of unconsolidated material, such as gravel or soil, cannot always be successfully accomplished with standard ro tary core drills. Such samplings of unconsoli dated material are commonly done, for example, during prospecting of placer gold -deposits. In this case, the heavier gold is usuaily found at the bottom of unconsolidated material resting on top of bedrock. For this reason, the prospector would normally want to sample only the material in the two feet immediately above the bedrock.

Vibratory core sampling apparatuses have been suggested in the past as seen, for example, in United States Patents 3,301,336 and 3,352,160, both to Mount. However, neither of these patents gives structural details of the vibrator, nor discusses the nature of the vibration.

In some earlier core drills which may be referred to as vibratory drills, the actual down ward movement of the drill is accomplished by percussion. In other words, the drill bit hammers through the material being sampled.

The percussion can result in the loosening of the threaded connections on the core barrel and, moreover, may result in failure of the drill steel through crystalization of the metal.

Another problem associated with obtaining core samples of unconsolidated material is retaining the desired sample within the core barrel as it is withdrawn. Loose material, such as gravel, silt or organic material, tends to drop out of the bottom of the core barrel.

Accordingly, core drilling apparatuses such as those in United States Patent 3,301,336 to Mount and United States Patent 3,833,075 to Bachman employ flexible fingers to retain the sample, The fingers are bent out of the path of the core sample as it enters the barrel, but resist movement of the sample in the opposite direction when the barrel is moved upwardly. These flexible fingers are not always sufficient to retain the core sample, particularly if it is composed of wet silt or the like.

It is desirable in many cases, such as placer gold prospecting to retrieve a sample at a certain depth, while discarding material above the sample. One approach to accomplishing this is found in United States Patent 4,130,170 to Holman which discloses a probe for use in geological surveys. The probe has a side outlet located a distance above the bottom so that material is retained only between the outlet and the bottom. However, the outlet is located only a few inches above the bottom which means that only a small length of core sample can be taken. The probe has no means for varying the length of core sample taken.

Other core sampling devices are disclosed in United States Patents 3,023,820 to Desvaux; 3,049,185 to Herbold; 3,805,898 to Whitney and 3,515,230 to Tomaine.

According to the invention, a vibratory, core drill apparatus comprises a housing and an eccentric member rotatably mounted in the housing for vibrating the apparatus when the eccentric member is rotated about an axis of rotation. There is means for connecting a rotary power source to the eccentric member to rotate the eccentric member. There is also means for connecting to the housing a core drill stem with a longitudinal axis so the longitudinal axis is perpendicular to the axis of rotation of the eccentric member.

The apparatus may also include a side ejector core sampler having a top end with a threaded fitting for connecting the sampler to the housing or a core drill barrel, a bottom end with a threaded fitting for connecting the sampler to a drill bit or to a core drill barrel, a side opening between the top end and the bottom end, and an internal passageway communicating outwardly through the bottom end and the side opening.

The apparatus may further comprise a core retaining bit having a top end with means for connecting the bit to the bottom end of the sampler or below a drill barrel connected to the bottom end of the sampler, a bottom end, a longitudinal passageway extending between the top end and the bottom end, and an open-ended flexible tube positioned within the passageway. Material moves upwardly relative to the drill bit during drilling and passes through the tube. The tube collapses to retain material when drilling stops.

Preferably, the bit furthwer comprises a plurality of flexible fingers having bottom ends connected to the inner wall and converging upwardly in a generally conical shape. Each of the fingers has a top end which touches the top ends of other said fingers.

In the drawings: Figure 1 is a side elevational view of a vibratory, core drill apparatus, according to an embodiment of the invention, and a perspective view of a motor connected to the apparatus by a flexible power shaft, Figure 2 is an enlarged perspective view of the top portion of the apparatus of Fig. 1, Figure 3 is an exploded perspective view of the components shown in Fig. 3, Figure 4 is a perspective view of a side ejector core sampler from the apparatus of Fig. 1, Figure 5 is a longitudinal sectional view of the sampler of Fig. 4, and Figure 6 is a perspective view of a core retaining bit from the apparatus of Fig. 1 with the side wall broken away.

Referring to the drawings, and in particular Fig. 1, a vibratory, core drill apparatus 1 includes a housing 2 connected to the top end 4 of a core sampler 6. The core sampler has a bottom 8 connected to a core retaining bit 10. The housing 2 has an internal eccentric member, described below, which is connected to a motor 1 2 by a flexible power shaft 14.

The housing 2 and its internal eccentric member are shown in better detail in Figs. 2 and 3. Housing 2 is T-shaped, having a cylindrical portion 1 6 which is horizontal in use. Horizontal portion 1 6 has a cylindrical hollow interior 18 shown in Fig. 3.

An eccentric member 20, shown in Fig. 3, is rotatably mounted in cylindrical interior 1 8 of housing 2. Eccentric member 20 is an elongate member fitted with a pair of spacedapart roller bearings 22 and 24. There is a stub shaft 26 at one end of eccentric member 20 which projects from the housing 2 as seen in Fig. 2.

The eccentric member 20 is sealingly received within the hollow interior so that the hollow interior can hold an oil bath for the eccentric member. The oil bath serves both to dissipate heat and to lubricate the bearings.

At the end of housing 14 opposite stub shaft 26, the housing is sealed by a threaded plug 28 threadedly received within the interior of the housing. At the opposite end of the housing, a fitting 30 is threadly fitted within the interior of the housing. Fitting 30 has a central aperture 32 through which stub shaft 26 projects. An oil seal 34 on the fitting prevents oil from leaking through aperture 32 over the stub shaft. Fitting 30 has a male threaded portion 36 which receives a female threaded fitting 38 of flexible power shaft 14 as shown in Fig. 1. The flexible power shaft is of the type having a stationary outer casing with a flexible rotatable core. This core has an end which is square in section and fits within a similar-sized square section aperture in the end of stub shaft 26.The stub shaft and fitting 30 accordingly provide means for connecting the rotating power source to the eccentric member 30.

Eccentric member 20 is generally T-shaped between bearings 22 and 24. Two portions 40 and 42 are machined out of the eccentric member, leaving a flange 44. The center of gravity of the eccentric member is thereby eccentric relative to its axis of rotation 46 shown in Fig. 2. This axis is horizontal when the apparatus 1 is in use.

Housing 2 has a portion 48 which is vertical when the apparatus is in use. Vertical portion 48 is a hollow cylinder with a male threaded end 50 which provides means for connecting the housing to a core drill barrel.

In the case of apparatus 1, core drill barrel 52, shown in Figs. 1, 4 and 5, forms the casing for the side ejector core sampler 6. The female threaded top end 4 connects the sam pler to the housing or to another length of core drill barrel which is connected to the housing. The bottom end 8 has a male thread for connecting the sampler to the drill bit 10 as shown in Fig. 1 or to another length of core drill barrel. The sampler 6 has a side opening 54 between the top end and the bottom end and generally near the top end.

An internal passageway 56 communicates outwardly through the bottom end 8 and the side opening 54. The passageway 56 is coaxial with the longitudinal axis 58 of the core drill barrel 52 and curves outwardly to the side opening 54. As seen best in Fig. 4, the side opening is generally elliptical in shape.

Longitudinal axis 58 is perpendicular to the axis of rotation 46 of the eccentric member when the sampler is connected to the housing as shown in Fig. 1.

Referring to Fig. 1, core retaining bit 10 is connected to the bottom end 8 of the core sampler 6. The core retaining bit is shown in better detail in Fig. 6. Bit 10 has a female threaded top end 60 providing means for connecting the bit to the bottom end 8 of core drill barrel 52 of sampler 6 or a standard core drill barrel. Bit 10 is in the shape of an openended tube with a bottom portion 62 which tapers towards an annular cutting edge 64 at the bottom end of the bit. The bit has a longitudinal passageway 66 extending between the threaded top end 60 and the bottom cutting edge 64. Passageway 66 is defined by the generally cylindrical inner wall 68.

An open-ended flexible tube 70 is positioned within the passageway 66 of the bit.

The tube of the preferred embodiment is of sheet-like plastic, although other flexible materials could be used such as rubber or canvas. The flexible tube has a bottom end 72 held against the inner wall of the bit by a pair of retaining rings 74 and 76. The bottom end of the tube is wrapped over the bottom ring 76, while the top ring 74 is placed over the tube. The rings 74 and 76 are held tightly against the tapered bottom portion 62 of the bit by the threaded bottom end of the sampler 6. While the bottom end of the tube is held against the inner wall of the bit, the top end 78 is open and free. As seen in Fig. 6 for the preferred embodiment, the tube extends beyond the top end 60 of the bit. Material moving upwardly relative to the bit during the drilling process passes through the tube and keeps the tube open. However, when drilling stops, the tube collapses if the material starts to move downwardly towards the cutting edge 64 and consequently retains material within the bit and core drill barrel 52.

The core retaining bit 10 also includes a plurality of flexible fingers 80 for retaining samples within the core when the barrel is withdrawn. These fingers 80 comprise leaf springs, each having a bottom end 82 held against the inner wall 68 of the bit by the retaining ring 76. A rivet 84 connects each of the leaf springs to the ring 76. As seen, the flexible fingers converge upwardly from ring 76 in a generally conical shape. Each flexible finger therefore has a top end 86 which touches the top ends of adjacent fingers.

During downwards movement of the bit 10 and the core drill barrel 52, material moving upwardly relative to the bit pushes apart the flexible fingers and moves upwardly through flexible tube 70 and the barrel. However, when drilling stops, the flexible fingers close together in the conical shape shown in Fig. 6 to prevent material from passing downwardly through the bit.

In operation, apparatus 1 is assembled and oriented as shown in Fig. 1. When samples are being taken from relatively shallow depths, the apparatus may be used as is with housing 2 grasped by the driller's hands.

However, when drilling to greater depths, the apparatus can be attached to a standard drilling rig for ease of operation and to maintain proper alignment. The rotatable eccentric member 20 within housing 2 is connected to the motor 1 2 by the flexible power shaft 14 as described above. Motor 1 2 may be any suitable gasoline or diesel powered motor.

The rotational speed of the eccentric member is governed by that of the motor. For drilling above the water table in hard pan, glacial till or hard clay, a rotational speed of over 12,000 r.p.m. for eccentric member is preferable. This results in over 12,000 vibrations per minute at the bit 10. A typical small motor operates at 3,600 r.p.m., for example, so pulleys and V-belts may be used to increase the speed of member 20 by a factor of 4 to 14,400 r.p.m. With such an arrangment, gravel, sand or clay below the water table would be drilled with the motor at half throttle, while one-quarter throttle would be suitable for organic sediments, silt or quicksand to give the samples time to enter the tube.

Otherwise the drill could drop too fast. It has been found that a clockwise directional rotation of the eccentric member by flexible shaft 14, indicated by arrow 88 in Fig. 1, is preferable since this keeps the various threaded connections tight instead of the vibrations loosening them.

Sampler 6 can be connected directly to the housing as shown, or additional lengths of core barrel can be fitted between the sampler and housing if the distance between the surface and the sampling depth is greater than the length of sampler 6. Similarly, core retaining bit 10 can be connected directly to the bottom of the sampler to retrieve a sample as deep as the combined length of passageway 56 in sampler 6 and passageway 66 in core retaining bit 10. If a longer sampler is wanted, one or more additional lengths of core barrel are fitted between the sampler 6 and the core retaining bit 1 0. The driller can therefore retrieve any desired length of sample at any desired drilling depth. For example, if the bedrock is located 1 3 feet below the surface, the driller may wish to take a 3 foot sample on top of the bedrock.Ten feet of core barrel is screwed onto male threaded end 50 of housing 2 and then sampler 6 is screwed onto the bottom of the 10 foot length of core barrel. Assuming that the combined lengths of passageway 56 in sampler 6 and passageway 66 in core retaining bit 10 is approximately 2 feet, an additional 1 foot length of core barrel is fitted between the sampler and the bit.

With motor 1 2 operating, the apparatus is held with cutting edge 64 of the bit against the surface. Vibrations move the bit downwardly towards the bedrock. As the bit moves downwardly, material moves upwardly through passageway 66 in the bit, bending flexible fingers 80 outwardly. The material moves upwardly through flexible tube 70 and passageway 56 of core drill barrel 52 until it eventually reaches side opening 54. Material is expelled through side opening 54 until the cutting edge 64 reaches bedrock. At this point, the required sample of material is located between the side opening and the bottom of the bit. The apparatus is then pulled upwardly. The loose material may tend to move out through the bottom of the bit, but the upward pressure of moving material is removed from flexible fingers 80, so they return to the position shown in Fig. 6 to resist an outflow of material. At the same time, flexible tube 70 collapses, providing additional means for keeping the sample within the core drill barrel 52.

Since the drilling is accomplished by vibration instead of rotation or percussion, no cooling or lubricating water is required and uncontaminated core samples are retrieved from unconsolidated formations. Penetration speeds of up to 2 seconds per foot are achieved.

While gasoline or diesel power is suggested above, it may be appreciated that electric, hydraulic or pneumatic power could also be used.

Claims (21)

1. A vibratory, core drill apparatus comprising: a housing; an eccentric member rotatably mounted in the housing for vibrating the apparatus when the eccentric member is rotated about an axis of rotation; means for connecting a rotating power source to the eccentric member to rotate the eccentric member; and means for connecting to the housing a core drill barrel with a longitudinal axis so the longitudinal axis is perpendicular to the axis of rotation of the eccentric member.

2. An apparatus as claimed in Claim 1, wherein the housing is T-shaped.

3. An apparatus as claimed in Claim 1, wherein the housing has a cylindrical hollow interior which rotatably receives the eccentric member, the eccentric member being sealingly received within the hollow interior so the hollow interior can hold an oil bath for the eccentric member.

4. An apparatus as claimed in Claim 1, wherein the eccentric member has a center of gravity which is eccentric relative to the axis of rotation.

5. An apparatus as claimed in Claim 1, wherein the eccentric member has a stub shaft at one end thereof which projects from the housing, the power source being connectable to the stub shaft.

6. An apparatus as claimed in Claim 1, wherein the eccentric member is elongate and is fitted with a pair of spaced-apart bearings for mounting the eccentric member rotatably in the housing.

7. An apparatus as claimed in Claim 1, wherein the eccentric member is rotated clockwise by the power source.

8. An apparatus as claimed in Claim 1, wherein the eccentric member is rotated at a rotational speed of over 12,000 r.p.m. to create vibrations of 12,000 vibrations per minute.

9. An apparatus as claimed in Claim 1, wherein the axis of rotation of the eccentric member is horizontal when the apparatus is in use.

10. An apparatus as claimed in Claim 1, further comprising a side ejector core sampler having a top end with a threaded fitting for connecting the sampler to the housing or a core drill barrel, a bottom end with a threaded fitting for connecting the sampler to a drill bit or to a core drill barrel, a side opening between the top end and the bottom end, and an internal passageway communicating outwardly through the bottom end and the side opening.

11. An apparatus as claimed in Claim 10, wherein the passageway is coaxial with the sampler and curves outwardly to the side opening.

1 2. An apparatus as claimed in Claim 11, wherein the side opening is generally elliptical.

1 3. An apparatus as claimed in Claim 10, wherein the top end has a male threaded fitting and the bottom end has a female threaded fitting.

14. An apparatus as claimed in Claim 10, comprising a core retaining bit having a top end with means for connecting the bit to the bottom end of the sampler or below a drill barrel, a bottom end, a longitudinal passageway extending between the top end and the bottom end, and an open-ended flexible tube positioned within the passageway, so material moving upwards relative to the drill bit during drilling passes through the tube and the tube collapses to retain material when drilling stops.

15. An apparatus as claimed in Claim 14, wherein the tube is of a sheet-like material.

16. An apparatus as claimed in Claim 15, wherein the tube is of plastic.

17. An apparatus as claimed in Claim 14, wherein the bit has an inner wall defining the passageway, the tube having a bottom end held against the inner wall.

18. An apparatus as claimed in Claim 14, wherein the bit tapers towards an annular cutting edge at the bottom end.

1 9. An apparatus as claimed in Claim 1 7, wherein the bit further comprises a plurality of flexible fingers having bottom ends held against the inner wall and converging upwardly in a generally conical shape, each of the fingers having a top end which touches said top ends of other said fingers when drilling stops.

20. An apparatus as claimed in Claim 14, wherein the tube extends beyond the top end of the bit.

21. A vibratory core drill apparatus, substantially as hereinbefore described with reference to the accompanying drawings.