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Publication numberUS3770322 A
Publication typeGrant
Publication dateNov 6, 1973
Filing dateApr 12, 1971
Priority dateApr 12, 1971
Also published asCA962837A, CA962837A1, DE2216656A1, DE2216656C2
Publication numberUS 3770322 A, US 3770322A, US-A-3770322, US3770322 A, US3770322A
InventorsDelwin E Cobb, Carl L Kepner, Albert L Woody, Wayne E Roberts
Original AssigneeCaterpillar Tractor Co
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Apparatus for fracture of material in situ with stored inertial energy
US 3770322 A
Abstract
An earth working apparatus employs large amounts of stored energy which is cyclically delivered on demand to the work tool. The energy is stored in a large flywheel and delivered by suitable transmission means to the work tool.
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Description  (OCR text may contain errors)

United States Patent 1 Cobb et al.

[ APPARATUS FOR FRACTURE OF MATERIAL IN SlTU WITH STORED lNERTlAL ENERGY [75] Inventors: Delwin E. Cobb; Carl L. Kepner;

Wayne E. Roberts; Albert L. Woody, all of Peoria, 111.

[73] Assignee: Caterpillar Tractor Co., Peoria, 111.

[22] Filed: Apr. 12, 1971 [21] Appl. No.: 133,262

[52] US. Cl 299/37, 37/DlG. 18, 172/40,

299/14 [51]' Int. Cl A01b 35/00 [.58] Field of Search 172/40; 37/D1G. 18, 37/141 R, 141 T; 299/14, 37, 67; 198/10; 173/122 [56] References Cited UNITED STATES PATENTS 3,238,646 3/1966 Oldenburg ..37/141R 1 1 Nov. 6, 1973 3,293,778 12/1966 McAuliff 172/40 X 3,645,021 2/1972 Sonerud 37/141 T 3,367,716 2/1968 Bodinc 299/14 3,437,381 4/1969 Bodinc.. 299/14 X 3,443,327 5/1969 Martin 172/40 X 3,633,683 1/1972 Shatto 299/14 X Primary Examiner-Ernest R. Purser Attorney-Charles M. Fryer et al.

[57] i ABSTRACT An earth working apparatus employs large amounts of stored energy which is cyclically delivered on demand- ,to the work tool. The energy is stored in a large flywheel and delivered by suitable transmission means to the work tool.

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SHEET 1,70? 17 ENTORS DELWIN .COBB

- CARL KEPNER WAYNE ROBERTS BY ALBER WOODY I TORNEYS APPARATUS FOR FRACTURE OF MATERIAL IN SITU WITH STORED INERTIAL ENERGY BACKGROUND OF THE INVENTION This invention relates to earth moving and fracturing implements and pertains more particularly to a high energy mechanical apparatus for the storage and instantaneous delivery of high levels of energy to an implement for the fracturing or separation in situ of hard rock and other earth materials or the like.

A considerable amount of hard rock must be fractured yearly for the construction and mining industries. Most of this rock today'is fractured by drilling with percussion o'r rotary drills and blasting with dynamite or ammonium nitrate. This technique is expensive, slow, noisy and dangerous.

Mechanical tractor drawn rippers have been developed which will operate efficiently in relatively soft, weathered, flssured, layered or previously blasted rock. However, such rippers will not operate in hard rocks.

One of the major problems with theuse of rippers is the high forces that must be induced in rock and similar hard material to cause it to fracture. This necessitates the delivery of very high force and energy to the face of the rock or other material to be fractured or separated. Vehicles capable of delivering such forces statically would of necessity be enormous in size and cost and would thus be impractical.

Many exotic techniques have been proposed for fracturing earth formations. Such proposed techniques include sonic energy, electrical spark, water cannon, and others. Such techniques have shown the ability to fracture rock formations but have proven in most cases inefficient for commercial application. g

One such sonic technique is the employment of a resonant vibratory system. This system stores vibratory energy in a spring which may take many forms. The energy is thencyclically delivered to a vibrating tool at the resonant frequency of the system. The major problem with this system is that a spring large enough to store adequate energy would be too large to be practical. Another problem is that frequency is critical and varies with load such that there is a majorproblem of control.

Other proposals have been made to apply vibratory energy to an earth working implement. Such proposals have generally met with failure for one reason or another.

Air and hydraulic hammers are impractical because of their low efficiency. Such large amounts of energy are required to vibrate a tool for breaking rock that unreasonably large amounts of input power would be required.

The present invention is based on the application of the theory that a dynamic system is desirable for cutting and breaki'ngrock and other materials since large forces can be produced with a small average thrust. This is an important feature when the average thrust is limited by tractive effort and weight of a vehicle.

The average force will be proportional to the time the force is applied. For example, if 100,000 lb is applied for 1/10 of a second every second, the needed average force will be only 10,000 lb. The basic idea then is to put the desired force on and unload again as quickly as possible so that during most of the cycle the force is zero or small. If this can be done the average force, compared to the peak force, will be small. If it is as sumed that the work done in breakng rock does not depend on the rate of loading, then the total work and average power will not be affected by this pulse type of loading.

The peak power requirements, however, will belarge if the work is done in short pulses. This means that large amounts of energy have to be available to be released quickly when needed. For a flywheel-crank system most of the energy is stored as kinetic energy in the flywheel. For a vibrating mass-spring system, the energy cycles back and forth from potential energy in the spring to kinetic energy of the mass. In either case the force that can be developed by the tool is limited by the stored energy.

Large amounts of energy have to be available to produce large forces quickly. The reason for this is that the tool has to penetrate into the rock or soil before the needed force can be developed. If the rock or soil were rigid, little energy would be required. But since they act much like a spring, energy has to be released in order to develop the required force. As an example, assume that a tool in rock has a spring rate of 6 X 10*lb/in. and

the breaking force is 6 X 10 pounds. In this case, 30,000 in-lb of energy will be needed to break out a chip. If this is done at a frequency of 20 times a second then 91 horsepower will be required.

In the subject invention as applied to a ripper, the work that the ripper performs is of an intermittent nature, taking place only during a small part of the time required for the driving shaft of the ripper to make a complete revolution. Since the material being fractured is extremely hard, the instantaneous demand of the rippers exceeds that of the drive motors. Therefore, a flywheel or flywheels are placed on the drive shaft to store sufficient'energy to meet peak demands. During a greater part of the revolution of the driving shaft, the

motor power is used to accelerate the speed of the flywheel. During the part of the revolution when the work is done, the energy thus stored up in the flywheel is given out at the expense of its velocity. As the velocity of the flywheel changes, the energy it will absorb or give up is proportional to the difference between the squares of its initial and final speeds and is equal to the difference between the energy which it would give out if brought to'a full stop and that which is still stored in it at the reduced velocity. Hence E A I ("1 "2 n (21rN,/60) (1r N,/30) n 'n' N /30 I W Klg E A (W Klg) (11 /30 (N, N E (W K /5873) (N N,) E Energy release (ft. lbs) I Movement of inertia of rotating mass in lb. ft.

sec. W Weight (lbs) G Gravity 32.2 ft./sec./sec. at seal level K Radius of gyration in feet N,'= Revolutions per minute (RPM) before any energy has been given out N Revolutions per minute (RPM) at end of period during which energy has been given out n,= Angular velocity radian/sec. before any energy is given out n Angular velocity radian/sec. at end of period during which energy has been given out W K is a measure of the energy potential of a flywheel system in lb.-ft. at a given RPM and can be determined by the formula This formula is a derivative of the above formula for energy.

Extensive computer and soil bin model tests have been conducted on the subject concept as applied to a ripper. A model impact ripper has been built and tested in various rock materials to determine the feasibility of fracturing hard rock with an impact device constructed in accordance with the present invention. The performance criterion for the model was specific energy, and is defined as the amount of energy (in.-1bs.) required to fracture a unit volume (in?) of rock. Specific energy permits one to determine the amount of power necessary to obtain a given production (yd. /hr.) in a certain rock material. The specific energy of rocks vary.- The specific energy is calculated according to the following equation:

SE. N E D/W where SE. Specific energy (in.-lb./in.

N Number of impacts during a run D Density of rock (I ./in.')

W Weight of rock removed during a run (lbs) E Average Energy per blow (in.-lbs.)

It should be noted that the parameters must be considered collectively with a unique relationship existing between one another. The specific energy of the material being fractured is a significant factor.

With a steel spring of the type needed in a resonant system (a ripper shank, bar, spring), the maximum amount of potential energy that can be stored in a cubic inch of spring material is:

where S is the maximum axial stress that the material can endure and E is the modulus of elasticity. For a working stress of 40,000 psi of a spring material then, the stored energy will be (4 X lO) /(2) (30 X 80/3 26.7 in.lb./in. In a vibrating system using a column of uniform cross section for example, the maximum stored energy will be one-half of this value since the column will not be uniformly fully stressed throughout its length.

In contrast, a flywheel, can store much more energy than this'per cubic inch of steel. Use a thin annular ring rotating about its polar axis as an example. The tangential stress in the rotating ring is given by the equation:

In this case, w is the mass density of the ring, r is the radius, and n is the angular velocity. The kinetic energy in the ring'due to its velocity will be:

Where V is volume of ring. V l in. I(.E. A S 20,000 in.lb. for S 40,000 psi The ratio between flywheel and spring energies is, therefore at least: 20,000/13.35 or 1500 to 1. In other words, 1500 times more energy can be stored in the flywheel than in an equivalent amount of steel spring for a given stress level. In addition, the stress in the spring is fully reversed each cycle, while the stress in theflywheel at most goes from zero to the maximum cycle. Reversing thestress in the spring energy cycle can adversely affect the fatigue life of the spring.

In order to work the above ring at 40,000 psi, the flywheel would have to be quite largeor else rotate at a high speed. If the speed is limited to 1200 rpm with a wheel radius of 15 in. and a resulting stress of only 2600 psi, the energy in a cubic inch of the steel ring will be 1300 in.-lb. for an energy ratio of about I00. This is less than the 1500 ratio, but it is still a substantially significant advantage.

For breaking rock in situ in quantity, large forces and power are required. This means large energies per blow and many blows per minute. The prior art systems have been unable to meet these requirements.

The primary object of the present invention is to provide an earth working implement that is rugged and efficient and overcomes the above disadvantages of the prior art.-

Another object of the present invention is to provide an'earth working apparatus that is capable of storing large amounts of energy and selectively applying it to an earth working implement.

A further object of the present invention is to provide a dynamic system that is capable of delivering sufficient energy to a tool for earth working to be practical.

A still further object of the present invention is to provide a mechanical dynamic system that is capable of efficiently delivering high energy pulses to an earth working tool.

In accordance with the present invention large amounts of inertial energy is stored in a massive flywheel to be cyclically delivered to an earth working implement at peak power demand. Suitable transmission means including a crank and connecting rod is used to transmit the energy to an earth working implement such as a ripper.

BRIEF DESCRIPTION OF THE DRAWINGS The above and other objects and advantages of the present invention will become apparent from the following description when read in conjunction with the accompanying drawings in which:

FIG. 1 is an elevational view partially in section of a rock ripper incorporating a preferred embodiment of the present invention;

FIG. 2 is a plan view partially in section of the embodiment of FIG. 1;

FIG. 2a is a section taken along lines IIa-IIa of FIG. 1;

FIG. 3 is a sectional view taken along lines III-III of FIG. 1;

FIG. 4 is a sectional view taken along lines IV-IV of FIG. 2;

FIG. 5 is a sectional view taken along lines V-V of FIG. 2;

FIG. 6 is a sectional view taken along lines VI--VI of FIG. 2;

FIG. 7 is a sectional view taken along lines VII-VII of FIG. 2;

FIG. 8 is a sectional view taken along lines VIIIVIII of FIG. 2;

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US3238646 *Aug 20, 1962Mar 8, 1966Caterpillar Tractor CoLoader bucket with a vibrating blade
US3293778 *Mar 5, 1964Dec 27, 1966William H McauliffMaul impacting device for excavating buckets
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Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US3857609 *Sep 27, 1973Dec 31, 1974H FelixImpact ripper shank
US4003603 *Dec 1, 1975Jan 18, 1977Caterpillar Tractor Co.Impact means for ripper
US4042036 *May 23, 1975Aug 16, 1977Smith James EElectric impact tool
US4070064 *Jun 4, 1976Jan 24, 1978Caterpillar Tractor Co.Cooling system for rock ripper tip
US4187744 *Jun 19, 1978Feb 12, 1980Caterpillar Tractor Co.Apparatus for rotating track chain bushing
US4227744 *Jan 29, 1979Oct 14, 1980Caterpillar Tractor Co.Impact tip for impact rock breaker
US4229044 *Feb 12, 1979Oct 21, 1980Caterpillar Tractor Co.Clevis-mounted impact ripper
US4229045 *Dec 26, 1978Oct 21, 1980The Gurries CompanyResonant tool driving apparatus with tool stop
US4229046 *Dec 26, 1978Oct 21, 1980The Gurries CompanyTool driving apparatus and method
US4230369 *Dec 26, 1978Oct 28, 1980The Gurries CompanyPavement planing method and apparatus
US4251111 *Mar 30, 1979Feb 17, 1981The Gurries CompanyResonant beam for tool driving apparatus
US4252376 *Mar 30, 1979Feb 24, 1981The Gurries CompanyRipping tool driving apparatus
US4258956 *Mar 30, 1979Mar 31, 1981The Gurries CompanyMethod and apparatus for driving a single transversely elongated tool with a plurality of force transmitting beams
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US4318446 *Oct 10, 1978Mar 9, 1982Caterpillar Tractor Co.Linear motion impactor device
US4359102 *Mar 20, 1980Nov 16, 1982Resonant Technology CompanyResonance aided earth-working equipment
US4379595 *Feb 17, 1981Apr 12, 1983Caterpillar Tractor Co.Ripper with offset impacting means and slotted shank
US4382634 *Jan 26, 1981May 10, 1983Towmotor CorporationMaterial fracturing apparatus
US4444434 *Oct 20, 1981Apr 24, 1984Resonant Technology CompanyContinuous miner
US4453772 *Sep 27, 1982Jun 12, 1984Caterpillar Tractor Co.Modular impact ripper assembly
US4467539 *Jun 10, 1983Aug 28, 1984Resonant Technology CompanyResonance aided front end loader
US4666213 *Sep 27, 1985May 19, 1987Howard Artis NRock breaker tool
US4669784 *Feb 24, 1986Jun 2, 1987Palmer GrasseOscillated head and connecting element, with bearing support, for floor stripping machine
US4703838 *Sep 25, 1982Nov 3, 1987Caterpillar Tractor Co.Recoil damper for a reciprocating member
US4821808 *Feb 4, 1988Apr 18, 1989Resonant Technology CompanyResonantly driven earth moving blade
US4906049 *Nov 28, 1988Mar 6, 1990N. P. K. Construction Equipment, Inc.Ripper using a hydraulic hammer and a method for making the improvement
US5787786 *Sep 27, 1996Aug 4, 1998Sauer-Sundstrand - Control ConceptsDual hydraulic oscillator for the reciprocating cutter of an agricultural machine
US6269561 *Nov 9, 1999Aug 7, 2001Rockland Inc.Tiltable implement for excavator machines and the like
US6443526Sep 4, 2001Sep 3, 2002Lee A. ScarlettLubrication of oscillating head elements for floor stripping machines and method of using the same
US6609576 *Nov 28, 2000Aug 26, 2003Melvin HubbardMethod and apparatus for vibratory kinetic energy generation and applications thereof
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US9062437Oct 11, 2012Jun 23, 2015Ronald H. HallVibratory ripper having depth adjustable ripping member
US20040262019 *Mar 11, 2004Dec 30, 2004Hubbard Melvin LMethod and apparatus for vibratory kinetic energy generation and applications thereof
US20130092405 *Oct 18, 2011Apr 18, 2013Ronald HallVibratory ripper having pressure sensor for selectively controlling activation of vibration mechanism
USRE31164 *Mar 15, 1979Mar 1, 1983Caterpillar Tractor Co.Cooling system for rock ripper tip
EP0057791A1 *Dec 9, 1981Aug 18, 1982Caterpillar Tractor Co.Fracturing apparatus
WO1979000563A1 *Jan 29, 1979Aug 23, 1979Gurries CoPavement planing method and apparatus
WO1979001066A1 *May 9, 1979Dec 13, 1979Gurries CoRipping tool driving apparatus
WO1980001637A1 *Feb 12, 1979Aug 21, 1980Caterpillar Tractor CoImpact ripper
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Classifications
U.S. Classification299/37.5, 172/40, 37/904, 299/14
International ClassificationE02F5/32
Cooperative ClassificationE02F5/326, Y10S37/904
European ClassificationE02F5/32H
Legal Events
DateCodeEventDescription
Jun 12, 1986ASAssignment
Owner name: CATERPILLAR INC., 100 N.E. ADAMS STREET, PEORIA, I
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:CATERPILLAR TRACTOR CO., A CORP. OF CALIF.;REEL/FRAME:004669/0905
Effective date: 19860515
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:CATERPILLAR TRACTOR CO., A CORP. OF CALIF.;REEL/FRAME:004669/0905
Owner name: CATERPILLAR INC., A CORP. OF DE.,ILLINOIS