U.S. patent number 3,633,688 [Application Number 05/011,250] was granted by the patent office on 1972-01-11 for torsional rectifier drilling device.
Invention is credited to Albert G. Bodine.
United States Patent |
3,633,688 |
Bodine |
January 11, 1972 |
TORSIONAL RECTIFIER DRILLING DEVICE
Abstract
The sonic energy output of a sonic generator is coupled to a
torsional resonant circuit. The output of the torsional resonant
circuit is in turn coupled through an acoustic rectifier device to
a drive member such as a cutting tool. The rectifier provides
unidirectional high level pulses of resonant sonic energy to a
cutting tool causing such cutting tool to be rotationally driven in
a pulsating manner.
Inventors: |
Bodine; Albert G. (Van Nuys,
CA) |
Family
ID: |
21749524 |
Appl.
No.: |
05/011,250 |
Filed: |
February 13, 1970 |
Current U.S.
Class: |
175/55; 173/93;
173/49; 175/56 |
Current CPC
Class: |
E21B
7/24 (20130101) |
Current International
Class: |
E21B
7/24 (20060101); E21B 7/00 (20060101); E21c
003/02 () |
Field of
Search: |
;175/55,56,19
;173/49,93,14 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Champion; Marvin A.
Assistant Examiner: Favreau; Richard E.
Claims
I claim:
1. In a torsional sonic drill member and the like the combination
of:
a torsionally elastic member
periodic torsional force means directly coupled to said member for
torsionally oscillating said member about its longitudinal axis at
a torsional resonant frequency of the member,
means for driving said torsional force means,
a cutting tool, and
torsional rectifier means coupled to said elastic member and
located between said elastic member and said cutting tool for
transmitting a unidirectional portion of the oscillator cycle of
said member to said cutting tool, whereby said cutting tool is
caused to be unidirectionally driven in a pulsating manner.
2. The combination of claim 1 wherein the periodic force means
comprises an orbiting mass oscillator having multiple rotors phased
for causing torsional vibration of said member.
3. In a torsional sonic drill member and the like, the combination
of:
a torsionally elastic member,
periodic torsional force means coupled to said member for
torsionally oscillating said member about its longitudinal axis at
a torsional resonant frequency of the member, said force means
comprising an orbiting mass oscillator having multiple rotors
phased for causing torsional vibration of said member,
means for driving said torsional force means,
a cutting tool, and
torsional rectifier means coupled to said elastic member for
transmitting a unidirectional portion of the oscillatory cycle of
said member to said cutting tool, said rectifier means comprising
rectifier hammer means securely affixed to said elastic member
about the outer wall thereof, a tool tube member attached to said
cutting tool and having rectifier window means formed in the wall
thereof and means for rotatably biasing said hammer means toward a
wall of said window means, whereby said tool is caused to be
unidirectionally driven in a pulsating manner.
4. The combination of claim 3 additionally including an annular
sliding bearing wherein the tool tube member is coupled to the
torsionally resonant member by means of said annular sliding
bearing.
5. The combination of claim 93 additionally including a torsionally
elastic tube wherein the tool tube member is coupled to the
torsionally resonant member by means of a torsionally elastic
tube.
6. The combination of claim 3 wherein said means for driving said
oscillator comprises a mud turbine, said turbine adapted to be
activated by the downward gravitational flow of drilling mud.
7. The combination of claim 3 additionally including elastic
pillars wherein the tool tube member is coupled to the torsionally
resonant member by means of said elastic pillars.
8. The combination of claim 7 wherein said elastic pillars comprise
the structure formed by radially forming through the wall of said
cylindrical tool tube member, a plurality of elongated slots, the
longitudinal axes of which are parallel to the longitudinal axis of
said tool tube.
Description
This invention relates to a method and apparatus utilizing sonic
energy to drive a cutting tool, and more particularly to such
method and apparatus in which an orbiting mass oscillator is
utilized in conjunction with a torsional resonant circuit and
acoustic rectifier to provide unidirectional high level pulses of
energy to the cutting tool.
In the field of rock drilling, both rotational and torsionally
oscillating drills have been used. It has been found in each of
these types of tools that the continuous cutting action can cause
overheating and rapid dulling of the drill bits. In a torsionally
oscillating drill it is not possible to utilize drill bits which
are designed for optimum cutting because it is necessary to provide
a bit which can withstand the reversing motion and cut in both
directions. Reversing drills have been effective in earth boring
because the high Q elastic vibrations transmitted to the rock
formation by a torsionally oscillating drill bit subjects such
formation to a stress pattern which tends to more efficiently
fatigue the formation. It should be noted that a torsional system
has a large stroke at any given frequency compared to other types
of vibratory systems. Because of its large stroke, the torsional
system inherently provides a low impedance output. If such a system
is intimately coupled to a load it is susceptible to substantial
stroke reduction and energy drainage, with the result that the
system Q is greatly reduced. The technique and apparatus of this
invention effectively alleviates this problem of Q reduction.
Further, it greatly extends the life of the bit and enables highly
efficient cutting action.
This significant improvement is achieved by utilizing an acoustic
rectifier for coupling the sonic energy from the resonant vibration
system to the cutting bit.
As used herein, the term "rectifier" means a device which transmits
vibrational energy in one direction only, and is thus analogous to
an electric rectifier which converts AC to DC. This acoustic
rectifier couples unidirectional pulses of sonic energy to the
cutting bit during a portion only of a torsional vibration
cycle.
Means are provided for generating a torsional resonant vibration
mode in an elastic member and coupling the elastic member to an
acoustic rectifier, so that unidirectional high Q energy impulses
are transmitted to the cutting tool. Since the cutting tool motion
is unidirectional, the cutting edge is not dragged backwards
against the work, and it is possible to utilize a cutting tool
designed for high efficiency cutting in one direction. The
rectifier also provides an intermittent rather than a continuous
cutting effect, so that tool bit overheating and resultant wear are
reduced. An important feature of the acoustic rectifier is its
ability to extract energy from the resonant torsional system for a
time interval which is only a portion of the vibration cycle, so
that the resonant system is not so intimately coupled to the load.
The acoustic rectifier thus is able to extract a high energy pulse
from the high Q resonant circuit and therefor transmits a very high
force output into the workpiece for relatively short intervals of
time. The rectifier thus operates as an impedance transformer, and
converts the low impedance output of the torsionally resonant
system into a series of relatively short duration, high force
pulses to the workload. In certain embodiments of this invention it
is possible to use a low impedance, torsionally resonant system to
drive a tool intended for high impedance workload situations such
as rock drilling and concrete cutting.
It is therefore the principal object of this invention to provide
an improved technique and apparatus for sonic drilling.
Other objects of this invention will become apparent from the
following description taken in connection with the accompanying
drawings in which:
FIG. 1 is a partially sectioned view of a first embodiment of the
device of the invention as incorporated into core-drilling
equipment,
FIG. 2 is a cross-sectional view taken along the plane indicated by
2--2 in FIG. 1,
FIG. 3 is a cross-sectional view taken along the plane indicated by
3--3 in FIG. 1,
FIG. 4 is a partially sectioned view of a second embodiment of the
device of the invention as incorporated into core-drilling
equipment,
FIG. 4a is a partially sectioned view of a saw which may be
utilized in conjunction with the second embodiment,
FIG. 5 is a cross-sectional view taken along the plane indicated by
5--5 in FIG. 4,
FIG. 6 is a cross-sectional view taken along the plane indicated by
6--6 in FIG. 4,
FIG. 7 is a partial sectioned view of a third embodiment of the
device of the invention as incorporated into well-drilling
equipment,
FIG. 8 is a cross-sectional view taken along the plane indicated by
8--8 in FIG. 7,
FIG. 9 is a cross-sectional view taken along the plane indicated by
9--9 in FIG. 7; and
FIG. 10 is a cross-sectional view taken along the plane indicated
by 10--10 in FIG. 7.
It has been found most helpful in analyzing the device of this
invention to analogize the acoustically vibrating circuit utilized
to an equivalent electrical circuit. This sort of approach to
analysis is well known to those skilled in the art and is described
for example, in chapter 2 of "Sonics" by Hueter and Bolt, published
in 1955 by John Wiley and Sons. In making such an analogy, force F
is equated with electrical voltage E, velocity of vibration u is
equated with electrical current i, mechanical compliance C.sub.m is
equated with electrical capacitance C.sub.e, mass M is equated with
electrical inductance L, mechanical resistance (friction) R.sub.m
is equated with electrical resistance R and mechanical impedance
Z.sub.m is equated with electrical impedance Z.sub.e.
Thus, it can be shown that if a member is elastically vibrated by
means of an acoustical sinusoidal force F.sub.o sin.omega.t
(.omega. being equal to 2 times the frequency of vibration,)
that
Where .omega.M is equal to 1/.omega.C.sub.m, a resonant condition
exists, and the effective mechanical impedance Z.sub.m is equal to
the mechanical resistance R.sub.m, the reactive impedance
components M and 1/.omega.C.sub.m cancelling each other out. Under
such a resonant condition, velocity of vibration u is at a maximum,
power factor is unity, and energy is more efficiently delivered to
a load to which the resonant system may be coupled.
It is important to note the significance of the attainment of high
acoustical "Q" in the resonant system being driven, to increase the
efficiency of the vibration thereof and to provide a maximum amount
of power. As for an equivalent electrical circuit, the "Q" of an
acoustically vibrating circuit is defined as the sharpness of
resonance thereof and is indicative of the ratio of the energy
stored in each vibration cycle to the energy used in each such
cycle. "Q" is mathematically equated to the ratio M and R.sub.m.
Thus, the effective "Q" of the vibrating circuit can be maximized
to make for highly efficient, high-amplitude vibration by
minimizing the effect of dissipation in the circuit and/or
maximizing the effect of mass in such circuit.
In considering the significance of the parameters described in
connection with equation (1), it should be kept in mind that the
total effective resistance, mass and compliance in the acoustically
vibrating circuit are represented in the equation and that these
parameters may be distributed throughout the system rather than
being lumped in any one component or portion thereof.
It is also to be noted that orbiting mass oscillators are utilized
in the implementation of the invention that automatically adjust
their output frequency and phase to maintain resonance with changes
in the characteristics of the load. Thus, in the face of changes in
the effective mass and compliance presented by the load with
changes in the conditions of the work material as it is sonically
excited, the system automatically is maintained in optimum resonant
operation by virtue of the "lock-in" characteristic of applicant's
unique orbiting mass oscillators. Furthermore in this connection
the orbiting mass oscillator automatically changes not only its
frequency but its phase angle and therefore its power factor with
changes in the resistive impedance load, to assure optimum
efficiency of operation at all times. The vibrational output from
such orbiting mass oscillators also tends to be constrained by the
resonator to be generated along a controlled predetermined coherent
path to provide maximum output along a desired axis.
With reference first to the embodiment shown in FIGS. 1-3, there is
seen in FIG. 1 a partially sectioned view of the drill, comprising
an elastic drill stem and housing 11, and core barrel 12, each of
which is formed of a suitable alloy steel having good elastic
fatigue properties, preferably of circular cross section as shown
and of a diameter suitable for accommodating the components
installed therein. Typically though without limitation, the elastic
drill stem 11 and core barrel 12 may comprise a length of 5 to 20
feet. The lower end of stem 11 is machined to a reduced diameter to
form the drill stem pin 13, which fits loosely within the inside
bore 14 of core barrel 12, leaving an annular gap 15 between the
pin and the barrel. The shoulder of the juncture between stem 11
and drill pin 13 is provided with a highly polished annular bearing
surface 16 which is transverse to the longitudinal axis of the
stem. The upper surface of core barrel 12 is machined to a polished
bearing surface 17 which mates with surface 16 of the drill stem
and permits relative rotary motion between stem 11 and core barrel
12.
The upper end of the stem housing 11 is provided with an opening 21
through which the shaft 22 of motor 23 is disposed. The motor and
drill assembly is provided with suspension means 24 and an electric
cable 25 to provide electric current to the motor. There are
commercially available cables, which can be used here, to provide
both suspension and electrical conductor. The motor may also be
provided with a handle 26 if the drill is used above ground such,
for example, as in pavement-cutting work, and wall-engaging bails
27 if the drill is used for deep well drilling. Inside the upper
end of stem housing 11, mounted on shaft 22 is a gear 31,
permanently engaged with gears 32 which are fixedly mounted on
shafts 33. Shafts 33 are coupled through universal drive shafts 34
containing two universal joints each, to unbalanced oscillator
rotors 35. Each oscillator rotor has been unbalanced by drilling
out a hollow core 36 eccentric to its center. Each rotor is fitted
with a journal bearing fit into a lubricant retaining cavity bored
into the stem 11.
In the operation of the oscillator the rotors 35 are driven in the
same direction by means of motor 33, the gear train including gears
31 and 32 and drive shafts 34, and are caused to rotate inside the
cavities provided in the oscillator housing. The hollow cores of
the rotors are relatively positioned in such a manner so as to
cause torsional elastic vibration of housing 11, which is
resonantly transmitted through the stem 11 into the drill stem pin
13.
Turning attention now to the core barrel 12 there is seen the
mechanism comprising the acoustic rectifier. Cut into the walls of
the core barrel are three rectifier windows 41 spaced around the
circumference of the core barrel. Each window 41 is formed by
radially machining through the wall of the core barrel an elongated
slot, the major axis of which is parallel to the longitudinal axis
of the core barrel. The drill pin 13 extends for a sufficient
length inside the core barrel so that three rectifier hammers 42
may be secured by means of bolts 43 to the drill stem 13 in such a
manner as to protrude through the rectifier windows 41.
In the operation of the acoustic rectifier, the drill stem 11 is
caused to oscillate in a resonant torsional mode, so that pin 13
oscillates inside the core barrel 12. This causes the rectifier
hammers 42 to strike against one side of each rectifier window 41,
thus accomplishing the rectification and thereby causing the core
barrel 12, with its attached coring bit 51 and reaming teeth 52 to
be driven rotationally in one direction only. In addition to
causing the oscillator to operate, the torque developed by the
motor 23 also tends to cause the stem 11 to rotate. The greater
resistance there is to the operation of the oscillator, due, for
example, to hard rock cutting, the greater will be the torque
tending to turn the entire tool. This turning of the tool results
in a rotary bias of the hammers in their windows which helps
implement the rectifier action by causing the rectifier to be
acoustically coupled to the load only for torsional impulses in the
direction of the biasing action. In this manner the acoustic
rectifier is able to extract a small portion of the stroke of the
drill stem, and transmit to the working tool a high energy
unidirectional pulse of short duration. The average loading of the
load on the resonating drill collar is therefore greatly reduced,
resulting in a decreased energy drainage and high Q. It is
therefore seen that the acoustic rectifier provides the advantage
of permitting the acoustic energy to remain well established at a
high Q level in the resonant system, effectively transforming the
low impedance vibration cycle of the torsionally resonant system
into a series of high impedance, high force pulses for the
workload. The sliding bearing formed by the surfaces 16 and 17
allows the core barrel 12 to rotate relative to the drill pin 13.
In the operation of the tool, the motor, which can be driven by
means of electrical power provided through cable 25, drives the
oscillator, which may be of the type described in my U.S. Pat. No.
3,291,228, causing a standing wave to be developed in the drill
stem 11, the oscillator preferably being driven at a frequency such
as to cause resonant elastic vibration in the drill stem. The
cutting action generated by this tool is particularly suited for
applications such as the drilling or cutting of concrete and
rock.
In FIGS. 4-6 I have shown a second embodiment of the invention
suited for rock and concrete cutting, utilizing elastic pillars to
provide torsional compliance between the core barrel and the drill
stem.
Referring to FIG. 4 there is shown a second embodiment of the
invention suited for rock and concrete cutting, utilizing elastic
pillars to provide torsional compliance between the core barrel and
the drill stem.
Referring to FIG. 4 there is shown an oscillator 61 comprising
rollers 62 driven by crank member 63 and gear system 64, through
which torque is transmitted from motor shaft 65. The rollers are
driven so they roll in the same direction but are positioned
180.degree. out of phase, so that to and fro torsional vibrations
are thereby generated. A common housing 66 is employed to contain
the oscillator, and the stator 67 of an electric motor of which the
armature 68 is supported on shaft 65. Drill collar 71 is threadably
attached to the lower end of housing 66 by means of tapered threads
72. The drill collar may be formed of a suitable alloy steel having
good elastic fatigue properties and of a circular cross section
having a lower region diameter suitable for containment within the
tool tube 74.
The tool tube comprises an elastic cylindrical member formed of a
suitable alloy steel having good elastic fatigue properties, of
circular cross section, mounted by a secure press fit on a suitable
diameter 71a machined on drill collar 71. The drill collar is
formed such that a sufficient area is provided for a press fit with
the tool tube and the balance of the drill collar extends axially
inside the tool tube with a loose fit, leaving an annular gap 75.
The tool tube 74 is also provided with "elastic pillars" 76 which
are formed by radially machining elongated slots 77 through the
annular wall of the tool tube. The tool tube is additionally
provided with three rectifier windows 41 spaced about the
circumference of the tool tube. Acoustic rectification is
accomplished by the same means as in the first embodiment, the
rectifier of which is shown in the cross sectional view in FIG. 3.
The tool tube is fitted with a core bit 51 comprising a plurality
of teeth made, for example, from tungsten carbide. The tool tube
may also be fitted with a rotary saw blade 81 for the purposes of
stone or concrete cutting.
In the operation of this embodiment of the invention, torque
supplied by the motor shaft 65 sets into rotation gear system 64
and oscillator crankshafts 63. The gear system is designed such as
to cause the two parallel oscillator crankshafts to rotate in the
same direction with the same rotational velocity. Each cylindrical
oscillator roller 62 is thereby caused to rotate eccentrically in
its respective cavity 69 formed in the oscillator housing 66. The
rotors are aligned such that they are 180.degree. out of phase in
their positioning in their raceways thus causing a torsional
elastic vibration to be generated in the oscillator housing 66. The
oscillator is preferably driven at a frequency such as to cause
resonant elastic vibration along the drill stem or collar 71,
including the portion of the drill collar 71 which is loosely
fitted inside tool tube 74. A standing wave is therefore
established in said resonant drill collar 71. The mechanism of
acoustic rectification is of the same general character as that
described earlier for the first embodiment, but this second
embodiment is modified by the presence of the elastic pillars 76
instead of the sliding bearing that was utilized in the first
embodiment. The function of the elastic pillars is to allow the
drill collar to move inside the tool tube. The portion of the tool
tube in the region of the press fit must move with the drill
collar. However, the elastic pillars, because they are long and
narrow and therefore elastically soft, effectively isolate the full
cycle motion of the drill collar from the lower portion of the tool
tube. Thus the only motion experienced by the lower portion of the
tool tube is the rectified torsional oscillation delivered to the
tool tube by the rectifier hammers 42. The core bit illustrated in
the present case is shown to have a series of individual cutting
teeth, FIG. 4, but it will be understood that the form of the bit
is subject to wide variation.
The rotary torsional saw 81, shown in FIG. 4a, is intended as an
alternative form of tool mounted on the rectifier end of the tool
tube. The saw would be used alternatively to, and not in addition
to the core bit, and can be used by orienting the tool in such
manner that the longitudinal axis of the tool tube is approximately
parallel to the surface being cut, so that the saw can cut along
the surface in the fashion of a conventional rotary saw. This
device is especially effective for saw cutting concrete and
rock.
FIGS. 7-10 show a third embodiment of the invention in which a
torsionally elastic tube is utilized to couple the acoustic
rectifier to the torsionally resonant member. Referring now to FIG.
7 and turning attention to the lower end of the resonant bar 91
carrying rectifier hammers 92, torsional oscillation of this end
portion of the bar about its longitudinal axis oscillates the
hammers 92 in such manner as to transmit unidirectionally
rotational pulses to the torsionally elastic tube 93. Rectification
is accomplished in much the same manner as in the previous
embodiments, with the modification in this third embodiment that
the acoustic rectifier is coupled to the oscillator housing 94 by
means of a torsionally elastic tool tube 93 and rotary bias is
supplied by rotating the entire drill pipe from above. The tool
tube comprises a hollow, thin wall cylindrical member 93 formed of
a suitable alloy steel having good elastic fatigue properties, so
that the tube is torsionally limber in relation to the heavy
resonant drill collar 91 which is loosely fitted inside. Therefore,
the drill tube transmits very little of the full cycle motion of
the drill collar, onto which the tool tube is press fitted at its
upper extremity 95. The torsional oscillation of the drill collar
is therefore delivered to the lower region of the tool tube where
the rectifier is located, primarily by the action of the rectifier
itself. The rectifier delivers rectified rotary action to the drill
bit primarily in response to the impulses transmitted to the drill
tube in the region of the drill bit by the local action of the
rectifier hammers 92. The backward rotation of the drill collar on
each cycle is not strongly delivered to the drill bit because the
torsionally elastic tool tube 93 is limber enough that it does not
transmit very strong torsional force.
Torsional elastic vibrations are generated by a four-roller
oscillator 96 driven through gear system 99 by a turbine shaft 101.
As can be seen in FIG. 9 each roller 97 is fitted into a roller
cavity 98 machined into the oscillator housing 94. Each roller is
rotationally driven in the same direction by the crank members 102
coupled to gear system 99. The rollers are aligned in their
respective cavities in such manner as to generate torsional
oscillation. Turbine shaft 101 is coupled to the output stage of
mud turbine 104, the axis of which is parallel to the longitudinal
axis of the oscillator 96. Mud outlet passages 106 are provided by
forming holes in the oscillator housing 94 parallel to the rotor
cavities 98, so that the mud may flow downward through the housing
past the oscillator without effecting the gear system or oscillator
mechanism. At the bottom of the oscillator housing, mud which has
flowed through passages 106 collects in the annular cavity 108 and
continues to flow downward through the hollow core 109 of drill
collar 91 so as to deliver the mud out the bottom of the drill for
lubricating the drill bit and washing chips out of the hole. In
addition to the rectified torsional pulses applied to the drill bit
by means of the rectifier, a constant rotary bias is also applied
by slowly rotating the drill pipe from above the surface of the
earth, such as, for example, at 20 revolutions per minute. The
rotary bias which, as for the other embodiments, is utilized to
implement the rectifier action can be delivered through the elastic
tool tube to a small degree because the transmitted force is
normally much lower than the delivered by the rectifier action.
Nevertheless, even this rotary torsional force is primarily
transmitted through the rectifier. As in the other embodiments of
the invention there is a downward bias due to the mass of the tool
itself, which can be controlled by adjusting the suspension force
supporting the drill pipe at the earth's surface.
The techniques and devices of this invention thus provide means for
more effectively delivering torsional energy into the cutting bit
of a tool intended for drilling or cutting earthen material, rock
or concrete. By virtue of the rectification action of the
invention, high force pulses may be extracted from a high Q
torsionally resonant system to provide optimum coupling of energy
to the load. Further, such rectification of the torsional cycle
provides a unidirectional cutting action, which permits the
utilization of efficiently designed cutting tools without causing
undesirable overheating and short tool life due to backwards
dragging of the cutting tool over the work surface.
* * * * *