US 3336082 A
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Description (OCR text may contain errors)
Aug. 15, 1'9-67 A. G. BOBINE. JR
METHOD AND APPARATUS FOR RIP-PING ROCK BY SONICALLY VIBRATORY TEETHv 6 Sheets-Sheet l Filed Oct.. v, 1964 HHN ' A. G. BOBINE, JR 3,336,082 lMETHOD AND APPARATUS FOR RIPPING ROCK BY SONICALLY v'IBRAToRY TEETH Filed Oct. 7, 1964 l 6 Sheets-Sheet Au'g. l5, 1967 A. G. BOBINE. JR METHOD AND APEARATUS FOR RIPPING ROCK Aug. 15, 1967 BY SONICALLY VIBRATORY TEETH 6 Sheets-Sheet 3 Filed Oct. '7, 1.964
m T N E V m Aug. 15, 1.967
A; G. BOBINE, .1R 3,336, METHOD AND APPARATUS FOR RIPPING ROCK BY SONICALIJY VIBRATORY TEETH Filed OC.. '7, 1964 i,
e sheets-Sheet 4 TOR.
Aug. 15, 1967 A. G. BOBINE` JR 3,335,082 A METHOD AND APPARATUS 'FOR RIPPING ROCK BY SONICALLY VIBRATORY TEETH Filed oct. v, 1964 e sheets-sheet 5 k1 I K INVENTOR.
. 15,-.1967 A. G. B ODINE. vJR
METHOD AND APPARATUS FOR RIPPING ROCK lBY SNICALLY VIBRATORY TEETH 6' Sheets-Sheet G Filed oct. v, 1964 mwN ma NMWWMI...
United States Patent O 3,336,082 METHOD AND APPARATUS FOR RIPPING ROCK BY SONICALLY VIBRATGRY TEETH Albert G. Bodine, Jr., Los Angeles, Calif. (7877 Woodley Ave., Van Nuys, Calif. 91406) Filed Oct. 7, 1964, Ser. No. 402,136 16 Claims. (Cl. 299-14) This invention is concerned with methods of and means for ripping rock by the novel use of one or more sonically-vibrat-ory rock-engaging teeth or points carried by a powered vehicle which is adapted for travel over a bed of the rock. The lield of use is in earth Amoving operations wherein rock is encountered in regions where earth cutting is desired for changing the topography.
In past years it has been the practice to employ drilling and blasting with dynamite whenever rock was encountered. This activity became a major expense of building highways through mountain regions, where rock conditions are encountered as soon as any substantial depth of cut is planned, such as through mountain passes, and along the face of steep slopes. This same problem also is encountered in connection with land development, particularly where large earth moving operations result in exposing deep lying rock beds.
Some success has been accomplished using a xed ripper tooth on the back of a fairly large tractor. Here the pratice is to force this tooth through the rock, employing the relatively high thrust capability of the tractor, along with a hydraulic means for pulling the tooth up simultaneously with the forward thrust of the tractor. This technique has had some degree of success, particularly with the more weathered rock layers, or rock layers which are in a discontinuous condition in situ in the ground. Sometimes the tractor operator can improve the operation of the tool somewhat by backing the tractor up and then driving forward suddenly so as to cause the tooth to impact against the rock ledge. In other words the operator can sometimes make the tractor and tooth combination bang its way forward in a series of hammer-like blows. It has been found that ordinary tractor ripping, however, is very limited in usefulness. The technique is practically an economic impossibility with the harder rock materials. In addition, it is destructive of the tractor itself, the jolting being very destructive Vof the tractor drive mechanism particularly, and the tractor structure in general.
. There has been a need for a mechanical rock-cutting device because drilling and blasting is a very complicated procedure which tends to make earth moving costs very expensive, and the general object of the invention is the provision of a novel process .and apparatus for ripping .of rock for the elds of use mentioned, using sonic vibration of the rock engaging tooth or point to attain previously unknown success and wide scale commercial applicability and usefulness.
The invention involves my discovery that a sonically activated resonator, in combination with a tooth or point, and a high force output sonic vibration generator, has a Very unique and effective action in rock ripping.
The method of the invention comprises primarily the transmitting or radiation of sonic oscillation or vibration into .and through the rock material in a direction having a major component substantially parallel to the top surface Kof the rock layer. The method includes rst locating a sonic radiator element, such as a tooth or point, against a shoulder of the rock layer some distance down below the top surface thereof. This distance as contemplated by the invention is of the order of a few feet, but, of course, a shallower cut may be taken if desired. The sonic radiator point is then oscillated with a component of sonic vibration which is generally parallel to the top surface of 3,336,082 Patented Aug. 15, 1967 the rock, which may be either horizontal, or tilted. These sonic vibrations are to be transmitted through the rock, which is an elastic and frangible material, with a component of sonic wave or elastic vibration travel which is generally parallel to the top surface of the rock. By elastic vibration, I refer to the fact that sonic waves are propagated through an elastic medium by longitudinal wave movements that comprise alternate elastic compressions and rarefactions progressing through the rock with the speed of sound in the rock media. This sonic or elastic vibration or wave propagation causes the rock to literally come apart along fracture or weakness lines which are ahead of the sonic radiating tooth or point element. Because of the nature of elastic vibrations the top surface of the rock functions as a pressure release region, akin to or involving a sudden drop in acoustic impedance, so that a portion of the sonic wave energy transmission which works on these fracture lines tends to dive up from the sonic radiator point -up to the surface of the rock some distance ahead of the sonic radiator point. The action sometimes includes a sort of a refraction phenomena, caused by a slower speed of sound nearer to the surface, which directs components of the wave transmission along upward angles lof slope.
The angle at which these fracture lines predominantly tend to slope up from the point `determines the size of the rock fragments, to a degree.
Apparently the speed of sound varies somewhat in local regions when transmitting through rock near the surface. To understand this, a familiarity with the concept Iof .acoustic impedance is helpful, and for present purposes acoustic impedance may be regarded as the ratio of cyclic rock pressure to vibratory velocity amplitude when a sonic wave is propagated through the rock. The naturally occurring variations in the speed of sound and in the `acoustic impedance of the rock, on opposite sides of the various weakness zones or planes, result in stresses being built up across these weakness zones. These stresses are also attributable partly to the difference of the phases of stress and vibratory motion during the elastic cycle Ion opposite sides of the weakness zone or plane. The result is .a strong tendency toward failure at the weakness zone, so that, under the conditions of sonic wave transmission at high energy levels the rock tends to literally come apart, This must be understood as a 'unique surface layer phenomenon and performance, peculiar to the above-described sonic rock ripping operation.
This peculiar and surprising susceptibility of rock to rip apart with a sonically activated wave radiator tooth also involves a-phenomenon wherein cyclic tension stresses and fatigue failure are involved to a considerable degree. And if the sonic radiator point has a wedge-shaped configuration, the pressure from ythe wedge and the elastic vibrations therefrom create tension in the rock ahead of the Wedge, transversely of the medial plane of the wedge, such as is very destructive of rock material. This tension component is particularly elfective in this rock ripping operation, because, as above described, the operation is carried on near the surface of the rock, where there is practically no overburden weight which would place a compressive bias on the rock to counteract the tension cycle eifect.
I have .also found lthat the rock can frequently be caused to suddenly part or shatter, during the course of `sonic wave application, by momentarily applying an upward bias and thereby lifting up on the tooth assembly, so as to increase the magnitude of the tension phase of the elastic vibration cycle.
The basic steps of the method may be described as follows: I first insert the sonic radiator point below the top surface of the rock, into engagement with a shoulder region of the rock. Such a shoulder region is maintained subsequently by the forward progress of the tooth. The next step of the method is to exert a strong forward bras force on this point, which in turn concentrates this force in a very small area on the face of the shoulder. Thls bias is typically of the order of 20,000 to 100,000 lbs., usually the practical limit of the tractor draw bar pull, so that the pressure exerted by the point on the rock is exceedingly high in pounds per square inch. Moreover, the bias force is of the order of magnitude of the cyclic sonic vibration force, so that the vibration radiating point stays in engagement with the rock during a substantial part of the vibration cycle, so as to be well acoustically coupled to the rock, and thereby assure transmission of strong elastic vibrations or waves into and through the rock.
After the steps of engaging the point against the shoulder of the rock, and exerting the above-described bias force, I then generate an elastic resonant vibration in an elastic resonator which is acoustically coupled to the point.
The elastic resonator is of fairly high acoustic impedance, typically a steel bar weighing something of the order of half a ton. I nd it desirable that this resonator have a fairly high impedance, and having a substantial energy storage capacity, so as to have a substantial acoustic Q (the ratio of sonic energy stored to energy dissipated per cycle). The high acoustic Q factor causes the bar, or resonator, to build up an elastic vibration to a fairly high sonic amplitude, with the result that high force or stress vibrations are transmitted into the rock.
To briefly recapitulate, the method includes the first step of engaging the point with the rock, the second step of applying to the tooth a forward bias force, in a direction having a component parallel to the surface of the rock, and a third step of sonically driving the sonic radiation point, also with a component parallel to the top surface of the rock, by means of an oscillator operated at resonance, i.e., a resonator.
In addition, I generate these sonic vibrations in the resonator by acoustically coupling thereto a high-forceoutput oscillatory force-generator, or sonic vibration -generator, and `operating this generator at the resonant frequencypof the resonator. In summary it can be said that the basic method consists of maintaining the sonic radiator point in a region a little below the top surface of the rock, `biasing this radiator point against a shoulder surface on the rock, and resonating a resonant member which is acoustically coupled to this radiator point. One important aspect of the method of the invention is the use of an elastically vibratory driving bar or shank for the radiator point that has a component of vibration which is in the direction of the lbias force and which component is generally parallel to the upper surface of the rock. In other words, the resonant pattern selected for the resonator must be oriented to produce an elastic vibration having this important component of vibratory direction. In this respect it can be said that the method includes four requisite steps. Optionally and additionally, a sometimes useful additional step is to momentarily apply an upward component to the bias.
One preferred embodiment of the invention has the resonator in the form of a flat slab bar oriented generally vertically, so that it progresses through the rock edgewise. This wide bar is then resonated in a lateral or bending mode of standing wave vibration. The vibration is in the plane of the major lateral dimension of this flat bar. The bending mode in or in parallelism with the planes of the at sides of the bar yields a fairly high elastic stiffness, so that the bar vibrates naturally at fairly high frequency, and has a fairly high acoustic impedance. Such a ybar hanging free in the air, i.e., a free-free bar, would normally resonate at its fundamental frequency with a substantially one-wavelength pattern. This pattern has a node approximately one quarter of the distance in from each end (sometimes closer to about 0.17 of the distance) and therefore has velocity antinodes (regions of maximized vibration amplitude) at its two ends, and a velocity antinode in the center. In this lateral standing wave pattern, the two ends of the bar move in phase with one another, and the center portion of the bar moves in opposite phase to the two ends.
I have found it particularly desirable to cause a substantial modification of the above-mentioned wave pattern in the bar as a further desirable optional step in the practice of the method. This step involves causing the forward bias force to be so high relative to the fairly high impedance bar that the bar impedance becomes concious of its environment. That is to say, I cause the bias force to be so high as to cause the actual impedance of the rock to become part of the reactive circuit in a special function whereby it provides almost the entire acoustic reactance of the lbottom node. That is to say further, I cause the bias force to be so great in relation to the impedance of the bar that the high impedance normally presented by the node above the bottom quarter wavelength portion of the bar is substantially completely supplanted by the reactance of the rock itself. The result is that the wave pattern becomes more nearly three quarters wavelength rather than one full wavelength. In effect, the rock itself has replaced both the mass and stiffness parameters of the bottom quarter wavelength of the earlier postulated elastically vibratory free-free bar, and functions to provide almost all of the impedance function of the lowest node, so that the bar in effect behaves substantially as a clamped-free bar.
Assuming the bar to be generally vertically disposed, and to have a laterally directed tooth point at its lower end, it will be seen that the bar, resonating in a lateral mode, tends to give an arcuate motion to the vibration path of the ripper point. Therefore, lby forcibly imbedding the point into the rock, by the above-mentioned forward bias, this point is virtually clamped in all of its desired directions of resonant motion, so that the bar lbehaves nearly as if it were fully clamped at a node or near-node located in the region of the point. The main consideration, however, is that the bias itself is so great, in combination with the impedance of the rock, that the rock can provide almost all of the function of the bottom node in the resonant lbar. The bar thus vibrates substantially in a threequarter wave length pattern, with a node near the bottom, another node one-third of the length of the bar down from the top end, and antinodes at the top and two-thirds down the bar from the top. In actual practice, a true node 1s not obtained exactly at the point but somewhat thereabove, say one-sixteenth Wavelength thereabove. There 1s thus a small vibration amplitude at the point. The bar may `be mounted at its upper node, and is thus preferably arranged for pivotal movement about that node, as will be discussed hereinafter.
In the drawings:
FIG. l is a top plan View of a present illustrative embodiment of the rock ripper of the invention, the view being partly in section on broken line 1 1 of FIG. 2, and the view showing also, largely in phantom lines, a conventional tractor such as may lbe used for the purpose of the invention;
FIG. 2 is a side elevational view of the rock ripper and tractor of FIG. l, the tractor again appearing primarily in phantom lines;
FIG. 2a is an enlargement of a portion of FIG. 1;
FIG. 3 is a rear elevational view of the rock ripper of the invention, looking toward the left in FIG. 2;
FIG. 4 is an enlarged side elevational view of a portion of the rock ripper as seen in FIG. 2, portions being broken away to expose underlying structure;
FIG. 5 is a section taken on line 5 5 of FIG. 2;
FIG. 6 is a longitudinal, vertical and medial sectional view through the rock engaging point, the tooth on the vibratory bar and a fragment of the vibratory bar itself;
FIG. 7 is a detail elevational view taken as indicated bythe arrows 7-7 in FIG. 6;
FIG. 8 is -a diagrammatic side elevational view of theV vibratory bar of the invention, in typical engagement with a shoulder of bed rock during a ripping operation, and including a standing wave diagram representing the vibratory wave pattern in the bar; and
FIG. 9 is a view, similar to a portion of FIG. 2, but illustrating a modification of the invention.
A suitable tractor is designated generally by the numeral 10, and is of the fairly large type in present use in rock ripping operations where a fixed shank with a ripper point on the lower end thereof is employed. The tractor, being conventional, is shown primarily in phantom lines excepting in those parts having direct cooperation or connection with the improvements of the present invention. As indicated, it is typically of a type having crawler tracks 11. A drivers station, intermediate the length of the tractor, is indicated at 12, and forwardly thereof are two engines 13. Dozer equipment, forming no part of the present invention, is indicated at 14.
At the rear of the tractor are two vertically disposed, rigidly mounted bracket arms 15, which are spaced from one another laterally of the machine, as clearly appears in FIGS. 1 and 2. As here shown, these bracket arms 15 are connected at their lower ends, as at *16,V to rigid frame bars 17, and at points intermediate thereof, as at 18, to stationary brackets 19 rigidly secured to the rearward end of the tractor. To the lower end portions of these bracket arms 15 are pivotally connected, as at 20, a pair of vertically swingable arms 21, which mount at their rearward or swinging ends a horizontally disposed, transverse tool bar or beam 22 of box section. As indicated, the tool bar .or beam 22 is tted into notches 23 formed in the forward end portions of arms 21, and is securely welded to these arms. Bracing webs 21a are welded between arms 21 and tool bar 22.
To the upper ends of bracket arms 15 are pivotally connected hydraulic lifting cylinders 24, containing pistons 24a on shafts 25 whose lower ends are pivotally connected to the arms 21 as at 26, as shown best in FIG. 2. As will be seen from FIGS. 1 and 2, the arms 21 have thickened wall portions 2lb which are spaced to provide grooves 21e which receive the lower pivotal end portions of the shafts 25. By means of the described piston and cylinder combination, and a source of later mentioned hydraulic uid connected to the lower ends of the cylinders, the arms 21, tool bar 22, and vibratory ripper equipment mounted on the latter may be swung vertically between a lowered operative position and an elevated carrying position.
Two generally vertically disposed elastically vibratory sonic bars or Shanks 30, bearing rock ripper points P, are employed in the present illustrative equipment, being mounted rearwardly of opposite end portions of the tool bar 22, through mounting arrangements as now to be described. Welded to the top and bottom sides of tool bar 22, in line with each of sonic bars 30, are a pair of flat, upper and lower, limit plates 32, projecting somewhat rearwardly from the tool bar, and formed with angle sided, rearwardly facing notches 33. A pair of bar mounting castings 34 are provided, one for each sonic bar or shank 30, and each such casting 34 has a pair of lvertically spaced upper and lower arms 36 and 37, respectively, which t over a pair of bosses formedon the upper and lower plates 32 as shown. A generally vertical pivotal mounting pin 38 extending down through a drill hole 39 in members 36, 32, 37, and the tool bar 22, serves to mount the castings 34 for limited lateral pivot movement on the tool bar 22. As will be seen, the castings 34 are received partially within the notches 33 of the limit plates 32, and their possible moving angles are thereby limited.
The rearward end portions of the castings 34 are formed with deep grooves 40, extending generally vertically therethrough, and with the side walls of the grooves in parallel vertical planes longitudinal of the tractor. The aforementioned sonic bars or shanks 30 comprise liat slabs of steel (elastic material of good elastic fatigue properties), of rectangular section, with their flat, vertical sides also in parallel planes longitudinal of the tractor. These bars or shanks 30 are received in the grooves 40, and are spring-urged (biased) toward the bottoms of the grooves, i.e., in the forward direction of the tractor vehicle, by pairs of coil springs 44 received in and between opposed spring-seating cups 45 and 46. The middle portions of forward cups 45 bear against lthe rearward edges of shanks 30. A support plate 48 bears against each rearward cup 46, and long bolts 49 running through lugs 47 on the sides of casting 34, the springs 44, cups 45 and 46, and plate 48, secure the parts in assembly. These parts are further supported by long screws 49a which run through the top part of plate 48, spacer sleeves as indicated, and into lugs 49b on the sides of casting 34. In operation, the springs 44 are substantially compressed by the bars 30 because of resistant of the rock being ripped, and the`bar 30 rides and vibrates at good clearance distance from the bottom of the groove 40, excepting momentarily from time to time as the rock splits or fragments. Preferably, the springs 44 are tuned to be three-quarters of a wavelength long for the resonant vibration frequency set up as hereinafter described in the shanks or bars 30, so as to substantially isolate the vibration of the bars from the support castings 34. Acoustically speaking, the springs then have high impedance points of zero or minimized vibration amplitude at the support castings, while Vibrating at good amplitude at the opposite ends with the vibration of the bars 30. The springs are thus resonated at the operative frequency of the bars.
Each bar 30 has a nodal point mounting at a point which preferably is approximately one-third of its length down from its upper end, so as to 4be at approximately the node N at the one-third point down from the top of a three-quarter wavelength lateral standing wave pattern st (FIG. 8). This mounting for each bar 30 includes a pair of spaced support brackets 50, one on each side of the bar 30, which are mounted on and erected from the corresponding casting 34. Suitable working clearance is provided between the sides of the vibratory bar 30 and brackets, as indicated in FIG. 5.
The brackets 50 for each bar are provided at the top, substantially coaxial with the upper nodal point of the bar, with cylindric heads 52 having coaxial bores 53 therethrough. Seated in the bores 53 are short cylinders 55 containing resilient rubber rings 56, preferably bonded therein, which in turn contain and have bonded therein the rim members 57 of hubs 58 which are rotatably.
mounted on a node pin or sleeve 60 set tightly into a bore 61 formed in the bar 30 concentrically with the top nodal point N of the latter. This preferred mounting will be seen to furnish a resilient support for the node pin 60 and bar 30 near or at the top node of the bar, one-third wavelength distance down from the top, as well as a pivotal support for the bar 30 on the axis of the node pin.
It will of course be understood that the nodal point N of the bar 30 is a point Where the amplitude of standing wave vibration pattern in the bar is minimized, or substantially zero; but there will, in practical situations, still be some small vibration at this node. The resilient rings 56 absorb such vibration and prevent its transmission down the brackets 50 to the casting 34, the tool bar, etc.
A vibration or sonic wave generator 64 is rigidly mounted on or in the top end of each bar 30, so as to be acoustically vcoupled to the latter. This vibration generator preferably of a type to be described presently, is driven through a shaft 65 from a uid motor 66. The latter is supported on a mount or carriage 67 which is pivotally mounted on the axis of node pin 60, and is spring urged toward a normal centered position elative to the bar or shank 30. As here shown the mount 67 is fastened down to spacers 68 xed to pillow blocks 69 which surround and are supported by the extremities 70 of a shaft 71 that protrudes through sleeve 60. Bushings 69a are used in pillow blocks 69 to afford a rotative fit with shaft extremities 70. Nuts 73 on threaded portions of shaft 70 are set up against end plates 74 for brackets S0, and said end plates 74 engage and close the outer ends of cylindric bracket heads 52. The end plates engage shoulders on enlarged sections 75 of shaft 70, and are clamped thereagainst by setting up the nuts 73. The maximum diameter of shaft 71, at section 75, is afforded good clearance space inside node pin or sleeve 60, so as to avoid vibratory engagement therebetween with any possible vibration of sleeve 60 with the vibratory bar 30, notwithstanding the nodal location of the sleeve 60. Thus, the motor 66 and its mount 67 are rotatably mounted about the nodal axis of the bar 30.
Motor mount 67 includes a pair of side walls 80 (FIG. 4) which are provided, in alignment with the opposite edges of bar 30, with apertures 81 which receive coil compression springs 82, and the springs 82 seat in cups 83 which are connected and supported against the walls 80 by long bolts 85. The springs 82 bear against the edges of bar 30, above the nodal point or axis N' of the bar 30, `and act to resiliently or yieldably hold the motor mount 67 centered with bar 30. Thus, as the bar 30 swings rearwardly about the nodal pin axis (nodal pin 60 turning in hub 58) against the springs 44 upon engagement of the point P with the rock, the motor mount is caused to turn correspondingly so that the fluid motor 66 retains good axial alignment with the sonic generator 64 being driven thereby.
To operate properly, the springs 82 are preferably onequarter wavelength long (or odd multiple thereof) for the resonant vibration frequency of the system. The upper end portion of the bar 30 can then vibrate laterally about its node point without causing undue vibration of the uid motor. The one-quarter wavelength springs (for the operating frequency of the bar 30) present high impedance at their points of engagement with the motor mount 67, and low impedance at their points of engagement with the laterally vibratory bar 30, and thus serve to isolate the motor mount from the vibration of the bar. The motor thus stands relatively steady while the bar vibrates. The nature of the coupling between the motor and the barmounted generator is such as will readily accommodate the small resulting cyclic misalignment of the axis of the motor relative to the vibration generator.
The vibration generator 64 can be any generator which will apply a transversely oriented alternating force of the necessary magnitude to the upper extremity (antinode) of the bar 30. It may also have (but need not have) an alternating force component longitudinal of the bar. For this reason, I can employ some desirable forms of vibratory force generators which generate .a rotating force Vector. In such cases, it is generally only the lateral corn ponent of this force vector that is utilized, because the rotating force vector is caused to turn at a frequency equal to or approximately the resonant frequency for the desired mode of ylateral standing wave vibration in the bar 30. The effect of the longitudinal force component can then be neglected because it does not cause longitudinal resonance. For a simple example of a vibration generator which I may use, and which produces a rotating -force vector, I may cite a simple unbalanced flywheel, or a crank. A more sophisticated generator, that here indicated, is of a type such as disclosed in several of my copending patent applications, viz, Vibration Generator for Resonant Loads and Sonic Systems Embodying Same, Ser. No. 181,385, new Patent No. 3,217,551, and Sonic Method and Apparatus for Forming Trenches and for Laying Pipe Lines Therein, Ser. No. 258,216, filed Feb. 13, 1963, now Patent No. 3,256,695 which are incorporated herein by this reference. In these generators, the drive from the motor to the generator is through a conically gyratory shaft, such as the shaft 65 of FIG. 5, which is shown as having a head 88 formed with arcuate splines 89 which mesh will coacting splines 90 inside a drive cup 91 driven from the shaft of fluid motor 66. The opposite end of the conically gyratory shaft 65 drives a rotor mass which rolls around the inside of a raceway in the body of the generator, thus creating a rotating force vector which may be -resolved into two alternating force components actin-g with phase difference therebetween. These parts are not shown herein, being no part of the present invention, and may be seen in any of said copending applications. Generators of the type of that here referred to, as disclosed in said copending applications, may also be used in synchronized pairs, so as to balance out the force component longitudinal of the bar, while causing the force components transversely of the bar to be equal and opposite. Por simple example, assume two unbalanced ywheels, side by side, on parallel shafts, geared together to turn in opposite directions at the same speed, and phased so that the eccentrically located centers of gravity of the two fiywheels always move horizontally -in unison, but vertically in opposite directions. An alternating force component will then be generated only horizontally, and not vertically. It will be obvious how pairs of the rotor mass generators of the type shown in said copending applications can be used here, by causing them, through simple gearing of their drive shafts, to be similarly phased, so as to generate an alternating force horizontally, or laterally of the bar 30, without a vertical or longitudinal component. For additional details of such rotor mass vibration generators, the aforementioned applications should be consulted.
The vibration generators 64 here shown have cylindrical housings 95 and are fixed to the upper extremities of bars or shanks 30 by installation in apertures 96 formed in the shanks 39 near the tops of the latter. The upper ends of the Shanks are split down into the apertures 96, as at 97, and clamp bolts 98 extending transversely through the bars, across the splits 97, are set up tight to hold the generators rigidly in place in the upper extremities of the shanks 30, and thus acoustically coupled thereto.
The point P on the lower extremity of each shank 30 is shown in a typical form in FIGS. 6 and 7. This structure as here shown is substantially as heretofore utilized in non-vibratory rock ripping, and involves no novelty per se. The point P, as usual, has a socket 99 which receives a tooth 99a welded to the lower end portion of the bar 30 at or ladjacent the lower end of the latter, and the point P is connected to the tooth 99a by a removable pin 100.
The hydraulic cylinders 24 and the uid motor 64 for the vibration generators are powered by hydraulic fluid from pumps 104 and 105 (FIG. l) driven from power take-01T shafts 106 leading through suitable transmission means, not shown, from the engines of the tractor. The pumps 104 and 105 are shown positioned inside reservoir tanks 106 and 107, respectively, and the pumps take the hydraulic Huid, preferably oil, directly from the reservoir. The pump is a dual pump, and has two outlets 108 and 109 which pump hydraulic uid via flexible hoses 110 and 111, respectively, to the two fluid motors 66 associated with the vibration generators for the two vibratory bars or shanks 30. Flexible return hoses 112 land 113 return the exhaust fluid to the reservoir. By-pass valves C are connected between each pair of lines 110, 112 and 111, 113 and are used when the pump 105 is in operation, to lfeed the hydraulic pressure uid either through the hydraulic motors 66 to drive the oscillators at maximum effort, or to return it partially or wholly to the reservoir. These valves are indicated only diagrammatically in FIG. l, and for convenience of illustration, have been shown out at the uid motors. It will be understood that in practice they will more conveniently be located back in the area of the pump or reservoir, and will have control means, not
shown, by which they may be manipulated from the operators position.
The other pump 104 is connected through suitable conventional control valve means, not shown, to feed hydraulic liuid via hoses 116 to or from the lower ends of hydraulic elevator cylinders 112, and via hoses 117 to or from the upper ends of said cylinders 112, for elevation of the tool bar 22 and equipment carried thereby, in order to raise the lower end of the shanks 30 to an inoperative carrying position or to drop them to a selected working position such as indicated in FIG. 8.
The full lnature and operation of the system should now be understandable. -The tractor is driven over the surface s of the rock to be ripped, with the tool bar 22 lowered (by means of hydraulic cylinders 24) until the shank points P are in engagement with a shoulder of the rock at a suitable distance below the surface s on which the crawler tracks of the tractor will be understood to be travelling. By driving the tractor forward, large bias force is exerted by the shank points P on the rock. At the same time, the by-pass valves V will have been manipulated to cause flow of hydraulic uid through the motors 66, thus the driving the sonic wave or vibration generators 64, and thereby causing the shanks to vibrate in their earlier described standing wave pattern. The pump pressure and valve positions are adjusted so that the generators 64 are driven at the resonant -frequency of the bars or shanks 30 .for a lateral mode of standing wave vibration, as mentioned earlier, and to be further described hereinafter.
It will be seen that the draw-bar pull of the moving tractor is exerted at the upper nodal point mountings of the vibratory shanks 30. Owing to the resistance of the rock, the shanks 30 swing back somewhat, against the opposition of springs 44, about the nodal point axis. If the rock does not give away, the springs will of course be substantially compressed, meaning that the full or maximum draw bar pull of the tractor then acts against the shanks 30 and their points P which are engaged against the rock. This substantial draw bar pull, often combined with an upward pull through use of the elevator cylinders, will sometimes break the rock. Ordinarily, however, and in the process characteristic of the invention, the vibatory action of the shanks and points against the rock results in the rock progressively giving way, and the springs 44 lare thereforenormally not compressed to maximum position. The forward bias force on the rock is thus the draw bar pull transmitted via theA shanks 30 to the points P through the partially compressed springs 44. The tractor operator, with experience, can adjust the tractor effort, and achieves best results when a vibratory action is maintained, with the draw barfpull (bias) high but little less than the force which completely compresses the springs 44. Preferably, also, the springs are made suiciently stiff, in relation to the cyclic force impulse of the sonic wave generator, that a draw =bar bias force can be exerted by the tractor, up to a magnitude of the order of the cyclic sonic force magnitude delivered at the point, without causing bottoming out of the coil springs 44;
As explained hereinabove, the points P -under these con- `ditions are tightly engaged into the rock shoulder, and
tend to become wedged in place. The rock presents a very high impedance to the points, and their vibratory movement toward and from the rock becomes very small in amplitude, but very high in cyclic force application. The action tends toward that of a node, i.e., a region of minimized vibration amplitude. In practice, a typical performance may be achieved such as represented in the standing wave diagram st of FIG. 8, where the horizontal width between the lines represents the lateral vibration amplitude of the bar at corresponding points along the latter. In FIG. 8, a bottom node N appears a short fraction of a wavelength distance above the lower extremity of the bar, i.e., above the point. At the lower extremity, and therefore at the point, a small vibration amplitude is displayed. This is a high impedance point, and great cyclic force is applied thereat against the rock. At this same time, the upper node occurs at N', approximately one-third the distance down from the upper end of the shank, and velocity antinodes V occur at the upper extremity of the shank, and at the halfway point between nodes N and N'. A small rudimentary antinode appears at the lower extremity and is marked V. Thus the performance is Ibasically of the nature of a one wavelength standing wave pattern, but with a preferred substantial modification toward or substantially to a threequarter wavelength pattern, at correspondingly lower resonance frequency than would be the case if the bar were hanging freely. The modification is accomplished through the tendency ofthe relatively sharp wedge-shaped point to embed itself in the rock, by high bias force (draw bar pull at node N', or draw bar push on the lower region of the back edge of bar 30) and is aided also by the location of the upper mounting for the bar at a location approximately one-third the length of the bar down from the upper end.
Under these conditions, achieved by the methods and means now described in detail, a very novel form of rock ripping is accomplished, as was described in detail in the introductory part of the specification, and therefore need not be completely redescribed at this point. It should be stressed, however, that a cyclic force of high impedance, comparable with the impedance of the rock, is exerted by the wedge-shaped points on the rock. These points, effectively acoustically coupled to the rock, larg-ely by virtue of their high impedance vibration in combination with the high bias force application, radiate sonic waves or vibrations into the rock. The vibrations of the point, the bias force, and the radiated sonic vibrations, all have substantial or predominating components which are, in general, parallel to the top surface of the rock. The rock, so treated, fails and literally flys apart along -fracture lines or planes located ahead of the point. The vibrating point, engaging or wedging into the rock, actually places the rock in cyclic tension transversely across the medial plane of the point, tending toward both simply pulling the rockV apart, and also leading to fatigue failure of the rock. The operator may occasionally, during the vibratory action, suddenly pull up on the points by means of the hydraulic lift cylinders, which sometimes, under the prevailing conditions of vibratory action, results in instantaneous fracturing a substantial quantity of the rock.
The function of the Vertical pivotal mountings of the bar support casting 34 is to permit free lateral swinging movement of the castings 34 and bars 30 as the tractor turns, so as to avoid overstressing side loads between the vibrating bars 30 and the opposed guide surfaces in the castings 34 under these conditions.
FIG. 9 shows a modified mounting of the tool bar from the tractor, involving a parallel linkage which maintains the vibratory point-carrying shanks in a predetermined orientation, preferably approximately normal to the longitudinal direction of the tractor, regardless of how positioned by the elevator. The tractor is designated at 130, and carries at the rear vertical bracket arms 131, suspending hydraulic cylinder elevator means 132, pivotally linked as at 133 to tool bar 134. The latter may be the same in general respects as the bar 22 of FIGS. l and 2. Welded to the top and bottom of tool bar 134 are plates 136 and 137, understood to be notched out to the rear the same as the limit plates 32 of FIGS. l and 2, but extended forwardly from the tool bar to afford pivot mountings for the shank support castings 138. Thus, pivot pins 139 pivotally mount the arms 140 and 141 of castings 138 on plates 136 and 137.
The tool bar 134 has upper and lower ears 146 and 147, which are pivotally connected at 148 and 149 to upper and lower link arms 150 and 151, respectively, which arms are pivotally mounted at 152 and 153, respectively, to brackets 154 secured in any way to the main frame of the tractor.
The casting 138, of which there may be two, as in FIGS. 1 and 2, has associated therewith a normally approximately vertically disposed vibratory shank 160, carrying a point 161, and excepting for the mounting arrangements for the casting 138, said casting, the shank 160, the spring-bias means 162, the nodal mounting 163 for the shank, the vibration generator 164, and the fluid motor 165, may all be like the corresponding components more particularly illustrated in FIGS. l to 8.
It will be seen that the parallel linkage mounting arrangement for the tool bar in FIG. 9 is such that the directional orientation of the vibratory bar 160 relative to the tractor is undisturbed as the tool bar 134 is raised or lowered by the elevating means 132.
It will be understood that the drawings and description are merely illustrative of and not restrictive on the invention, particularly in its broader aspects, since various changes in design, structure and arrangement may be made without departing from the spirit and scope of the appended claims. Reference is here made to my copending application entitled, Sonic Earth Moving Process and Machine, Ser. No. 163,802, filed Ian. 2, 1962, now abandoned.
1. A sonically vibratory rock ripping machine, comprising:
a power motivated vehicle having a forward thrust,
an elongated elastic bar mounted on said vehicle so as to extend generally vertically and transversely of the direction of said forward thrust, and so as to have upper and lower ends, said bar being elastically vibratory at a resonant frequency in a wave pattern characterized by a lateral mode of standing wave vibration in a vertical plane parallel to said direction of forward thrust, with at least one nodal point between its upper and lower ends, at least one velocity antinode therealong, and with a vibratory portion at its lower end,
a rock engageable rock ripper point acoustically coupled to said lower end of said elastic bar directed generally in the direction of said forward thrust,
bar supporting means on said vehicle including a bar mounting affording support for said bar and through which the forward thrust of said vehicle is applied to said bar, and
a vibration generator for vibrating said bar at said resonant frequency coupled to said bar in a region of substantial vibration amplitude thereof and being arranged for application to said bar of a cyclic force which has a substantial component laterally of said bar.
2. The subject matter of claim 1, wherein said bar supporting means includes means for lowering and elevating said bar relative to said vehicle between positions above and below the surface being traversed by the vehicle.
3. The subject of claim 1, wherein said bar mounting includes a resilient vibration isolator element.
4. The subject matter of claim 1, wherein said generator is of the orbital mass rotor type, including a drive shaft disposed along a drive axis parallel to said nodal point axis,
a iluid drive motor for said vibration generator having a drive shaft on said drive axis coupled to said drive shaft of said generator,
a source of pressure uid and a return reservoir on said vehicle, and
exible hoses connecting said source and reservoir with said fluid motor, said hoses affording freedom for vibration and of pivotal swinging movement of said bar on said nodal axis.
5. The subject matter of claim 1, wherein:
said bar supporting means includes a pivot joint affording a limited freedom for lateral swinging action of said bar mounting and bar.
6. The subject matter of claim 1, wherein said elongated elastic bar is wider than it is thick, so as to have relatively wide side surfaces, and is oriented on the vehicle with its wide side surfaces in planar, substantially parallel relationship with the direction of travel ofthe vehicle.
7. The subject matter of claim 1, wherein said vibration generator is rigidly mounted on said bar adjacent the upper end of the latter, said generator being of the orbital mass rotor type.
8. The subject matter of claim 7, wherein said generator includes a drive shaft disposed along a drive axis parallel to said nodal point axis,
a drive motor for said vibration generator having a drive shaft on said drive axis coupled to said drive shaft of said generator,
support means for said drive motor pivotally mounted on said bar supporting means for swinging movement about said nodal point axis, and
spring means between said support means and said bar at a point along said bar above said nodal point axis for maintaining said drive motor in substantial alignment with said vibration generator.
9. A sonically vibratory rock ripping machine, comprising:
a power motivated vehicle having a forward thrust,
an elongated elastic bar mounted on said vehicle so as to extend vertically and transversely of the direction of said forward thrust, and so as to have upper and lower ends, said bar being elastically vibratory at a resonant frequency in a wave pattern characterized by a lateral mode of standing wave vibration in a vertical plane parallel to said direction of forward thrust, with at least one nodal point between its upper and lower ends, at least one velocity antinode therealong, and with a vibratory portion at its lower end,
a rock engageable rock ripper point acoustically coupled to said lower end of said elastic bar directed generally in the direction of said forward thrust,
bar supporting means on said vehicle including a bar mounting affording support for said bar about a nodal point axis transverse to the bar and substantially through said nodal point, and through which the forward thrust of said vehicle is applied to said bar,
spring means acting between said vehicle and said bar at a point of the bar spaced from said nodal point and in a direction to springbias said point against rock engaged thereby, and
a vibration generator for vibrating said bar at said resonant frequency coupled to said bar in a region of substantial vibration amplitude thereof and being arranged for application to said bar of a cyclic force which has a substantial component laterally of said bar.
10. The subject matter of claim 9, wherein said spring means is tuned to resonate at the resonant operating frequency of the vibratory bar, so as to present a low impedance at the bar and a high impedance at the vehicle.
11. The subject matter of claim 9, wherein said bar mounting supports said bar at a point spaced generally one-third of the length of the bar down from its upper end, said .bar mounting and said ripper point being so located relative to said bar that, with said point in tight rock engagement, said standing wave for resonance is characterized by the location of said nodal point at said bar mounting, the provision of a second nodal point shortly above the lower end of said bar, and a rudimentary antinode at the lower extremity of the bar.
12. The subject matter of claim 9, wherein said bar mounting pivotally supports said bar at a point spaced substantially one-third of the length of the bar down from its upper end, and wherein said spring means acts on said bar in the direction of said forward thrust at a vibratory point of said bar below the pivotal support of the bar.
13 13. The subject matter of claim 12, wherein said point has substantially the form of a wedge.
14. The method of ripping a rock layer in situ in the earth, that comprises:
engaging a sonic radiator point against a shoulder of the rock, below the top surface thereof, exerting a strong forward bias force on the point while it is in engagement with the rock, producing elastic resonant standing wave vibration in an elastically vibratory resonator member which is acoustically coupled to said point so as to vibrate said point with a component of sonic vibration which is generally parallel with the top surface of the rock, and generating said vibrations in said resonator member by acoustically coupling thereto a vibration generator operable in the frequency range of the resonant frequency of said resonator member, and driving said generator at said resonant frequency. 15. The method of claim 14, including also: exerting an upward bias force on said radiator point While said point is in engagement with the rock and is undergoing said component of sonic vibration. 16. The method of ripping a rock layer in situ in the earth, that comprises:
engaging against a shoulder of the rock a sonic radiator point which is on the lower end of an elongated, elastic, generally vertically disposed bar having a pivotal mounting in an upper region thereof,
setting up in said bar a lateral standing wave pattern, so as to impart to said radiator point a component of sonic vibration which is generally parallel with the top surface of the rock and which normally has a velocity antinode at the lower extremity thereof, with a node spaced thereabove, and
forcing said point against said rock with a -bias force of high magnitude, so as to modify the standing wave pattern by shifting said node downward toward said point on the lowerend of said bar.
References Cited UNITED STATES PATENTS 2,670,943 3/ 1954 Vogel 299-14 X 3,030,715 4/1962 Bodine 299-14 X FOREIGN PATENTS 519,046 3/ 1940 Great Britain.
43,610 12/ 1959 Poland.
ERNEST R`. PURSER, Primary Examiner.