US3863721A

US3863721A - Inertial orbital vibrating plow apparatus

Info

Publication number: US3863721A
Application number: US379583A
Authority: US
Inventors: Louis Joseph Scerbo; Jr William Wallace Wood
Original assignee: Bell Telephone Laboratories Inc
Current assignee: AT&T Corp
Priority date: 1973-07-16
Filing date: 1973-07-16
Publication date: 1975-02-04
Anticipated expiration: 1992-02-04

Abstract

An inertial orbital vibrating plow apparatus comprises a large inertia body including a vibration generator for producing an orbital vibration of the body about a rotation center. A plowshare depends from the inertia body to contact the soil. The body is mounted in a frame by mounts which transmit drawbar forces to the plowshare but which isolate the frame from movements of and forces on the plowshare. The center of mass of the body and plowshare is located so that the plowshare traverses an orbital upwardly inclined path as it advances into the uncut soil.

Description

United States Patent 1191 Scerbo et a1.

INERTIAL ORBITAL VIBRATING PLOW APPARATUS Inventors: Louis Joseph Scerbo, Randolph Twp., Morris County; William Wallace Wood, Jr., Denville, both of Bell Telephone Laboratories, Inc., Murray Hill, NJ.

Filed: July 16, 1973 Appl. No.: 379,583

Assignee:

US. Cl 172/40, 37/DIG. 18, 173/49, 248/9, 248/21, 267/137 Int. Cl E02f 5/02 Field of Search 172/40; 37/DIG. 18; 173/49; 299/14; 248/9, 21; 74/61;

References Cited UNITED STATES PATENTS l/1942 Rubissow 248/21 X 3/1966 Hirst et a1. 248/9 X [4 1 Feb. 4, 1975 3,516,260 6/1970 Wood, Jr. 172/40 X 3,564,825 2/1971 Gould et a1. 3,618,237 11/1971 Davis 3,685,591 8/1972 Ulrich et al 172/40 3,698,484 10/1972 Kinnan 37/D1G. 18 3,757,869 9/1973 Gagne 172/40 Primary Examiner-Clifford D. Crowder Attorney, Agent, or Firm-A. D. Hooper [57] ABSTRACT An inertial orbital vibrating plow apparatus comprises a large inertia body including a vibration generator for producing an orbital vibration of the body about a rotation center. A plowshare depends from the inertia body to contact the soil. The body is mounted in a frame by mounts which transmit drawbar forces to the plowshare but which isolate the frame from movements of and forces on the plowshare. The center of mass of the body and plowshare is located so that the plowshare traverses an orbital upwardly inclined path as it advances into the uncut soil.

2 Claims, 17 Drawing Figures Pmsmanfw 3863.721

SHEET 3 OF 5 FIG. /7

PATENTEIIFEB 4 I 3,863,721

SHEET UF 5 FIG. 4 I FIG. 5 FIG. 6 FIG. 7

PATH OF PATH OF PATH OF PATH OF ROTATION ROTATION ROTATION ROTATION OF CENTER OF TIP I OF POINT 56 OF POINT 58 FIG.

Fla 9 FIG. /0 76 I I 78/7 (K I POINT 56 TIP 60 CENTER 50 I POINT 58 FIG. /4

H I Fla/a x/ 66 I FIG /5 v I POINT 58 F TIP so -50 PAIENIEU m1 41915 sum 5 OF 5 1 t INERTIAL ORBITAL VIBRATING PLOW APPARATUS 3 BACKGROUND OF THE INVENTION 1. Field of the'lnvention r This invention relates to plowing apparatus and more particularly to vibrating plow apparatus for forming narrow slit trenches for the simultaneous laying of cables or flexible pipe therein.

2. Description of the Prior Art The installation of underground utility cables by drawing a plowshare or blade through the soil to form a narrow trench therein while simultaneously feeding the cable into the trench is known in the art. It is also known that theapplication of vibratory motion to the plowshare as it is being'drawn through the soil greatly increases the efficiency of the plowing operation and substantially reducesthe drawbar force required for pulling the plowshare-While itis known empirially that an orbital vibration motion of the plowshare or blade in which the blade moves upward as it advances into uncut soil is advantageous, it has been difficult to obtain such orbital vibrational motion in practice because of complex bearing and suspension problems involved.

Some existing plows have the disadvantage of utilizing rigid linkages to transmit vibrational forces from a vibration generator to the plowshare or blade. This in turn causes the forces on the plowshare .to be transmitted back through the stiff linkages to the prime mover or main body of the vehicle on which the plow is mounted. Thus the size of this vehicle must be quite large to reduce the resultant motions to an acceptable level for the operator and such large vehicles cannot be used in many off-the-road cable burial applications. Other existing plowing apparatus utilizing inertial structures or actuators to transmit vibrational forces to the plowshare provide vibrations in only one direction, i.e.,' linearvibrations, and accordingly are not as efficient as apparatus having orbital vibrating plows. Thus a need remains for plowing apparatus for providing an orbital vibrating motion to a plowshare which is substantially isolated from the prime mover or main vehicle body.

Accordingly, it is an'object of this invention to improve vibrating plow apparatus.

Another object is to provide plowing apparatus having an inertially orbital vibrating plowshare.

SUMMARY OF THE INVENTION The foregoing objects and others are met in accordance with this invention by plowing apparatus comprising a large inertia structural member oriented substantially horizontally in the desired direction of travel of the apparatus. A rigid plowshare depends from the inertia member to make contact with the soil. The inertia member is mounted in a frame by relatively soft suspension mounts comprising multilayer rubber sandwiches which effectively transmit drawbar forces to the inertia member but isolate the frame from forces on or movements of the inertia member. A vibration generator produces an orbital vibratory movement of the inertia member about a force center or center of rotation. The vibration generator advantageously comprises a hollow circular cavity near the geometric center of the member having rollers therein for movement thereabout in a circular orbit. The rollers are driven about the cavity by appropriate drive shafts from a power source to produce the vibrational motion of the member. The orbital vibratory motion of the member about its rotation center produces an orbital vibratory motion of the plowshare with the particular orbit being determined by the location of the center of gravity of the plowshare and inertia member with respect to the rotation center.

BRIEF DESCRIPTION OF THE DRAWING The invention will be more fully comprehended from the following detailed description and accompanying drawing in which:

FIG. I is a perspective view of the plowingapparatus of this invention;

FIG. 2 is a perspective view of the inertial actuator utilized in FIG. I;

FIG. 3 is a schematic representation ofa side view of the inertial actuator of FIG. 2;

FIGS. 4 through 7 illustrate the orbital paths traversed by various points on the actuator of FIG. 2 for a balanced configuration;

FIGS. 8 through 11 illustrate orbital paths similar to FIGS. 47, respectively, for a front mass configuration;

FIGS. 12 through 15 illustrate orbital paths similar to FIGS. 4-7, respectively, for a rear mass configuration;

FIG. 16 is a perspective view of another embodiment of the actuator; and

FIG. 17 is a sectional view along line I717 of FIG.

DETAILED DESCRIPTION As shown in FIG. 1, the plowing apparatus 101, of

this invention comprises in general a mounting structure or frame 2 in which an inertial actuator 4 which drives a plowshare is mounted. In the illustrative embodiment structure 2 is mounted on wheels 6 and designed for pulling by a prime mover such as a tractor, not shown, by the application of a pulling force to drawbar 8. Actuator 4 is mounted by appropriate suspension means or mounts 10, to be discussed in more detail subsequently, to frame member 12 which is pivotably mounted at pivots 14 to a substantially upright support member 16. Member 12 is also connected to member 16 through member 17 by a hydraulic cylinder 18 or equivalent force means which can be actuated to pivot member 12 about pivots 14 to thereby raise and lower actuator 4 and the attached plowshare with re spect to the ground.

It should be apparent that the primary functions of structure 2 are to provide a mounting platform for actuator 4, to transmit drawbar or pulling forces to actuator 4 and to raise and lower actuator 4 with respect to the ground. Thus structure 2 can be readily incorporated as an integral part of a prime mover or can comprise a boom or crane attachment to such prime mover as well as comprising a separately drawn structure as shown in the illustrative embodiment.

As shown in more detail in FIG. 2, inertial actuator 4 comprises a large inertia body or structure 20 to which a plowshare or blade 22 is rigidly attached in a downwardly depending relationship to make contact with the ground. Four suspensions mounts 10 are located at substantially the four corners of body 20 for mounting actuator 4 to frame 2 as previously discussed by a simple installation of bolts 25.

A primary function of mounts 10 is to transmit the drawbar forces from frame 2 to actuator 4 so that blade 22 can be drawn through the soil while simultaneously isolating frame 2 from movements of and .forces on actuator 4 produced by the plowing operation. Thus mounts 10 must meet the conflicting requirements of being stiff enough to transmit substantial drawbar forces while simultaneously being soft enough to be good isolation mounts. The indicated sandwich or layered construction for mounts l satisfies these conflicting requirements. Each mount comprises two stiff rubber blocks or

layers

24 and 26 between which an intermediate mass such as a metal plate 28 is sandwiched. Plate 28 acts as a tuned absorber to provide good isolation. Because of the high inertial load to stiffness ratio, body will appear as a fixed displacement exciter to the interior rubber layer 24. Plate 28 moves 180 out of phase with body 20 and because of its acceleration and the relatively high operating frequencies plate 28 effectively opposes the forces being transmitted from body 20 through layers 24 even though plate 28has a mass only a small fraction of that of body 20. These greatly attenuated forces and displacements are then transmitted to frame 2 by layers 26. The movement of frame or strucure 2 may be as low as 0.1 percent of the movement'of actuator 4. Accordingly, there is no requirement for a massive frame or prime mover as has been previously required by vibrating apparatus utilizing rigid linkages. v

Inertia body 20 is adapted to have mounted on the respective ends thereof balancing

weights

30 and 32 which will be discussed in more detail subsequently.

Weights

30 and 32 can be mounted by a simple bolt on installation such as by bolts 34.

Actuator 4 includes an exciter or vibration generator 36 for producing orbital vibrations or rotations of body 20 about a center of rotation identified by axis 40. In the illustrative embodiment exciter 36 comprises a roller eccentric exciter such as disclosed in the copending application Ser. No. 379,584 of L. J. Scerbo filed concurrently herewith and assigned to the assignee of this invention. For such an exciter, a cylindrical cavity 38 is formed in body 20 about the desired axis of rotation 40 which can be near the geometric center of body 20. Rollers 42 are driven about cavity 38 by appropriate driving apparatus as disclosed in the copending application to produce an orbital vibration or rotation of body 20 about axis 40. Various other vibration generators known in the art could be used to produce an orbital vibratory motion of body 20 about axis 40.

The motion of inertial actuator 4 will now be discussed with reference to a schematic illustration shown in FIG. 3. In the illustration point 50 represents the center of rotation of actuator 4 which can also be designated as the force center; point 52 represents the mass center of the entire actuator 4 including exciter 36; point 54 represents the combined mass center of inertia body 20 and blade 22;

points

56 and 58 represent the front and rear suspension points orsupport centers of actuator 4; and point 60 represents the tip of blade 22.

The motion of tip 60 of blade 22 is of primary interest because this along with the remainder of the front edge of blade 22 is the primary cutting portion of blade 22. The effectiveness of the cutting action of tip 60 is proportional to the product of the frequency of vibration thereof and the amplitude of the vibration per cycle in the direction of motion 70. This product is termed the amplitude-frequency product. Thus it is desirable to make the amplitude-frequency product as large as possible. The motion of tip 60 is the superposition or vector sum of the motion of the combined mass center 54 of body 20 and blade 22 and the rigid body movement of tip 60 with respect to mass center 54. Further, the motion of mass center 54 is out of phase with the motion of rotation center 50 since the actuator is an inertially limited system. Accordingly the motion of mass center 54 must first be determined.

The mass center 52 of the entire inertial actuator 4 can be considered as remaining fixed in inertial space during any orbital vibratory motion of actuator 4. When drive shaft 41 of vibration generator 36 drives roller 42 around cavity 38 as indicated by direction arrow 62 to produce a vibratory motion of actuator 4 the orbital vibratory path traversed by rotation center 50 and mass center 54 and hence the orbital vibratory path of tip 60 depends upon the relative location of mass center 54 with respect to rotation center 50. Three specific cases will now be discussed.

When mass center 54 coincides with rotation center 50, rotation center 50 traverses a circular vibratory path 64 as indicated in FIG. 4 where direction arrow indicates the direction of travel of the plow apparatus. Likewise, tip 60 traverses a circular vibratory path 68 as shown in FIG. 5. Suspension points 56 and 58 also traverse circular

orbital paths

72 and 74 as indicated in FIGS. 6 and 7, respectively. Mass center 54 can be made to coincide with rotation center 50 by proper dimensioning of body 20 and blade 22 or by the addition of balancing

weights

30 and 32 as needed on body 20. This configuration can be termed a balanced configuration.

When mass center 54 lies between front support point 56 and rotation center 50, the orbital paths traversed by center 50, tip 60, point 56 and point 58 are respectively designated by elliptical

vibratory paths

76, 78, and 82 in FIG. 8 11, respectively. The direction of travel of the plow apparatus is indicated by arrow 70. This configuration can be obtained by adding front weights 30 to body 20 while eliminating rear weights 32. This configuration is termed the front mass configuration.

When mass center 54 lies between rear support point 58 and rotation center 50, the orbital paths traversed by center 50, tip 60, front support point 56 and rear support point 58 are respectively shown by elliptical

vibratory paths

84, 86, 88 and 90 in FIGS. 12 15, respectively, with the direction of travel again indicated by arrow 70. This configuration can be obtained by adding rear weights 32 while eliminating front weights 30. This configuration is termed the rear mass configuration.

Inspection of FIGS. 5, 9 and I3 reveals that in the rear mass configuration shown in FIG. 13, tip 60 has a substantially greater amplitude per cycle in the direction of travel than does the balanced configuration of FIG. 5 or the front mass configuration of FIG. 9. Accordingly, for a given frequency of vibration the rear mass configuration of FIG. 13 will have a substantially greater frequency-amplitude product which, as previously discussed, indicates a more efficient cutting configuration. lnspection of FIGS. 5, 9 and 13 also reveals that only in the rear mass configuration does tip 60 advance upwardly into the soil during substantially the entire forward portion of the cycle. As previously discussed, this greatly enhances the efficiency of the plowing operation. It can also be observed that the orbit of tip 60 for the rear mass configuration also is relatively narrow compared to the amplitude in the direction of travel. Accordingly, skin friction losses'will be substantially lower for the rear mass configuration than for the other configurations.

In view' of the foregoing discussion, it is apparent that a rear mass configuration for actuator 4 provides a very desirable orbital vibration to blade 22. Such an actuator 4 can readily be obtained by adding balancing weights 32 to the rear of body 20 to move mass center 54 rearwardly to lie between rotation center 50 and a rear suspension 58. The rear mass configuration provides a relatively large frequency-amplitude product for the orbit by blade tip 60 by substantially increasing the amplitude without increasing the frequency of vibration. Thus the contact, bearing forces and power losses created in vibration generator 36 remain within design limits.

An inspection of FIGS. 6, 7, 10,11,14 and reveals that the amplitudes of the orbital paths traversed by

suspension points

56 and 58 are functions of the distance of the respective points from mass center 54. Accordingly, in the desired rear mass configuration, the orbital amplitude of the rear suspension point 58 is relatively small with the major component in a horizontal direction whereas the orbital amplitude of the front suspension point 56 is relatively large with the major component in a vertical direction. These large displacements of the front suspension point can have a degrading effect on the rubber sandwich suspensionmounts utilized over an extended period.

The suspension mounts for an actuator must provide both translational stiffness to transmit drawbar or pulling forces to blade 22 and rotational stiffness to counter the soil forces on blade 22 since these forces have a moment arm with respect to the suspension mounts. In the previously discussed embodiment of the actuator the use of spaced front and rear suspension mounts provided the required rotational stiffness. However, in accordance with a second embodiment of the invention now to be discussed in connection with FIG. 16, applicants are able to provide the required translational and rotational stiffness by utilizing only rear suspension mounts thereby eliminating the necessity for mounts at high displacement locations such as point 56.

The rubber sandwich mounts 10 previously discussed are not entirely satisfactory for a one point suspension system. When the rubber layers 24 and 26 are made thin enough to provide the required rotational stiffness, they become too stiff with respect to translational movements. However applicants have determined that there exists a location on actuator 104 which experiences significant translational movements only in the horizontal direction and has a negligible vertical component of movement. This location will lie rearwardly from the mass center and close to the rear balancing weights 132 depending upon the exact structure utilized. At this location, the rotational and translational stiffnesses can be effectively decoupled so that each can be provided by different apparatus.

As shown in FIG. 16, at the negligible vertical movement location, a torsion bar 106 extends through body 120 and extends from both sides thereof terminating in a mountingblock 108. For example, torsion bar 106 can comprise a bar which is mounted by a torsion spring 107 within a tube 109 mounted in body 120. As shown in section in FIG. 17, two

shafts

110 and 112 extend from opposite sides of block 108 substantially orthogonal to torsion bar 106. Block 108 is mounted within a housing 114, by rubber shear blocks or sand-' wiches 116. Housing 114 can be fastened to a frame such as frame 2, not shown by bolts or similar devices. Housing 114 includes

bearings

117 and 118 in the ends thereof through which

shafts

110 and 112 respectively extend so as to have free axial movement therein. When body 120 undergoes horizontal translational movements,

shafts

110 and 112 move freely back and forth in

bearings

117 and 118, respectively to accommodate such movements. The thickness 115 and shear area 123 of rubber blocks 116 is preselected to provide the desired stiffness to such translational movement. Simultaneously,

bearings

117 and 118 prevent

shafts

110 and 112, respectively, from rotating therein about any axis perpendicular to axis 119 of torsion bar 106. Accordingly, the rotational stiffness is determined by torsion bar 106 which can be designed by well known techniques to any desired value. For example, torsion bar 106 can comprise a first cylinder mounted within a second hollow cylinder by a rubber sleeve which has the required thickness to provide any desired rotational stiffness while having negligible effect on the translational stiffness. Both the translational and rotational stiffness are at levels which effectively isolate frame 2 from actuator 104.

In this embodiment utilizing only rear mounts, body 120 can be terminated just forward of vibration generator 136 if desired. This provides for a more compact plow design.

While the invention has been described with reference to specific embodiments thereof, it is to be understood that various modifications thereto might be made without departing from its spirit and scope.

What is claimed is:

1. An inertial orbital vibrating plow apparatus for forming a trench in the soil comprising in combination:

a mounting frame for receiving a force to move said apparatus along a preselected direction of travel;

a large inertia structural member having a center of rotation;

a plowshare rigidly mounted to and depending from said member to contact said soil, said member'and said plowshare having a combined mass center which is located to the rear of saidrotation center with respect to said direction of travel;

suspension means for mounting said structural member within said frame in such a manner that said force is transmitted from said frame to said member while said frame is substantially isolated from motions of said member, said suspension means including:

a torsion bar inserted through and having respective ends extending from said structural member, said bar being located to the rear of said rotation center with respect to said direction of travel and oriented substantially perpendicular to said direction;

mounting blocks rigidly mounted on said respective ends, said blocks including shafts extending therefrom substantially in said direction of travel",

a housing surrounding said blocks and adapted for connection to said frame;

bearing means in said housing into which said shafts extend, said bearing means allowing free movement of said shafts in said direction of travel and preventing movements in other directions; and

resilient mounting means for mounting said blocks to said housing to permit relative movement therebetween in said direction of travel; and

means for generating anorbital vibrating motion of said member about said center of rotation whereby said plowshare has an elliptical vibratory path with said path having a major axis inclined upwardly and forwardly with respect to said direction of travel.

2. An inertial orbital vibrating plow for forming a trench in the soil for laying a cable therein comprising. in combination:

a mounting frame for receiving a force to move said .plow along a preselected direction of travel;

a large inertia structural member having sides. a center of rotation and a cavity therein about said center of rotation;

vibration generating means including a plurality of rollers adapted for travel about said cavity and driving means for driving said rollers about said cavity to produce an orbital vibrating motion of said member about said center of rotation;

suspension means for suspending said member within plowshare rigidly mounted to and depending from said member and adapted to contact said soil to form said trench, said plowshare and said member having a combined mass center which is located to the rear of said rotation center with respect to said direction of travel, whereby said vibratory motion causes said plowshare to follow an elliptical vibratory path having a major axis inclined upwardly and forwardly with respect to said direction of travel.

Claims

1. An inertial orbital vibrating plow apparatus for forming a trench in the soil comprising in combination: a mounting frame for receiving a force to move said apparatus along a preselected direction of travel; a large inertia structural member having a center of rotation; a plowshare rigidly mounted to and depending from said member to contact said soil, said member and said plowshare having a combined mass center which is located to the rear of said rotation center with respect to said direction of travel; suspension means for mounting said structural member within said frame in such a manner that said force is transmitted from said frame to said member while said frame is substantially isolated from motions of said member, said suspension means including: a torsion bar inserted through and having respective ends extending from said structural member, said bar being located to the rear of said rotation center with respect to said direction of travel and oriented substantially perpendicular to said direction; mounting blocks rigidly mounted on said respective ends, said blocks including shafts extending therefrom substantially in said direction of travel; a housing surrounding said blocks and adapted for connection to said frame; bearing means in said housing into which said shafts extend, said bearing means allowing free movement of said shafts in said direction of travel and preventing movements in other directions; and resilient mounting means for mounting said blocks to said housing to permit relative movement therebetween in said direction of travel; and means for generating an orbital vibrating motion of said member about said center of rotation whereby said plowshare has an elliptical vibratory path with said path having a major axis inclined upwardly and forwardly with respect to said direction of travel.

2. An inertial orbital vibrating plow for forming a trench in the soil for laying a cable therein comprising, in combination: a mounting frame for receiving a force to move said plow along a preselected direction of travel; a large inertia structural member having sides, a center of rotation and a cavity therein about said center of rotation; vibration generating means including a plurality of rollers adapted for travel about said cavity and driving means for driving said rollers about said cavity to produce an orbital vibrating motion of said member about said center of rotation; suspension means for suspending said member within said frame to transmit said force from said frame to said member while isolating said frame from said vibratory motion, said suspension means including front and rear mounts on each said side of said member to the front and rear of said rotation center, respectively, with respect to said direction of travel, each said mount comprising first and second blocks or resilient material respectively mounted to a respective said side and said frame and a rigid metal plate sandwiched between said first and second blocks; and a plowshare rigidly mounted to and depending from said member and adapted to contact said soil to form said trench, said plowshare and said member having a combined mass center which is located to the rear of said rotation center with respect to said direction of travel, whereby said vibratory motion causes said plowshare to follow an elliptical vibratory path having a major axis inclined upwardly and forwardly with respect to said direction of travel.