Resonant Beam for Tool Driving Apparatus

The present invention relates generally to power driving mechanisms, and more particularly to apparatus utilizing a vibratory member for driving tools or other members of various types into earth, coal, wood, concrete, asphalt, or other materials or substances.

In my application, Ser. No. 973,163, filed Dec. 26, 1978, is described tool driving apparatus in which one extremity of a straight resonant beam is mounted adjacent to a tool in the form of a cutter blade. A sonic generator is mounted on a tool holder or carrier that is driven by a continuous unidirectional force. The sonic generator is coupled to the other extremity of the resonant beam to set up resonant vibration therein with two nodes spaced along the length of the beam between its extremities. A pivotable upper node support and a rigid lower node support are provided for the respective nodes. The tool is advanced intermittently along a work path responsive to the continuous unidirectional force exerted by the carrier and the force exerted by the sonic generator.

The space requirements for a straight resonant beam and its node supports place burdensome restraints on the design of resonant power driving equipment for a number of different work applications, such as, for example, rock ripping, bulldozing, and earth moving with a shovel bucket or front end loader.

According to the invention, an angle beam serves as a force transmitting member between a sonic oscillator and a work tool. The angle beam has two divergent legs meeting at a juncture. Preferably the legs diverge at or near an angle of approximately 90 degrees. Such a force transmitting member permits the sonic oscillator to be located in a plane displaced a substantial distance from the plane in which the tool is located and requires approximately one-half of the longitudinal space of a force transmitting beam having the same characteristics.

A feature of the invention is a resonant beam that exhibits a single central node when restrained from vibrating at such node and a node support located at the single node. In the case of the described angle beam vibration of its juncture is prevented and sonic vibrations are applied to one end of the angle beam at a resonant frequency thereof. This establishes a node at the juncture and anti-nodes at the ends of the beam. By so driving the angle beam, a relatively long lever arm is provided by each of the beam legs so that a larger stroke is produced than a two-node, straight beam having the same length and the node support can be spaced further from the work tool by virtue of the larger distance between the node and the anti-nodes. Another feature of the invention, is an ear extending from the juncture for the purpose of fixing the beam position is a pivotable node support. The angle beam is driven so it has a single node at its juncture and along a nodal plane approximately intersecting the angle formed by the legs of the angle beam. The ear lies in this nodal plane so that the entire node support structure is isolated from vibration.

The features of a specific embodiment of the best mode contemplated of carrying out the invention are illustrated in the drawings, in which:

FIG. 1 is a side elevational, partially cut away view of tool driving apparatus embodying the invention, with portions broken away;

FIG. 1A is an enlargement of a portion of FIG. 1;

FIG. 2 is a top plan view of the left, operative portion of the apparatus illustrated in FIG. 1;

FIG. 3 is a fragmentary sectional view taken along line 3--3 of FIG. 1;

FIG. 4 is a fragmentary sectional view taken along line 4--4 of FIG. 1;

FIG. 5 is a graphical illustration of the operating characteristics of the described tool driving apparatus;

FIG. 6 is a fragmentary sectional view of a slightly modified version of the apparatus in FIG. 3; and

FIG. 7 is a side view of an alternative version of a portion of the apparatus of FIG. 1.

Tool driving apparatus employs a vibrating member in a fashion that such vibration of the beam or other force transmitting member will be maintained, regardless of various other forces applied during operation of the apparatus. To achieve such objective, the tool, which in the present embodiment of the invention takes the form of a ripping tool, is supported for pivotal motion from a tool frame adjustably supported at the rear of a mobile carrier in the form of a more or less standard tractor, the pivotal support being essentially transverse to the direction of motion of the tractor so that the tool, in turn, swings forwardly and rearwardly along the general direction of tractor motion. The tool frame, through its adjustable support, can be raised or lowered, and when lowered, the ripping tool can lie several feet below the surface of the earth or other material being engaged thereby.

To impart earth-cutting reciprocal motion to the ripping tool, a resonant member is utilized, and, more particularly, takes the form of an angle beam having a pair of legs supported in angular relationship from a pivotal support carried by the side plates of the tool frame so that one leg projects substantially vertically downward to lie adjacent the rear surface of the ripping tool whereas the other leg extends from the first leg at a divergent included angle of approximately ninety degrees and thus substantially horizontally forward between the frame plates, to mount at its extremity a sonic generator, eccentric weight oscillator or other means for energizing resonant vibration of the angle beam. The pivotal support therefor is at a central node position so that substantially no vibration is transmitted back to the supporting frame. The angle beam has lateral dimensions no greater than that of the ripping tool so that it can lie beneath the surface of the earth or other material being cut by the ripping tool without interfering with the operation.

A short ear extends from the angle beam upwardly from its node position and lies adjacent a stop member disposed between the plates, thus to restrict the pivotal motion of the angle beam about its pivot rod in one direction. Shims, or other means, can be used to provide for adjustment of the position of shim engagement of the ear, and thus define the neutral position of the resonant angle beam, and more particularly the lower tool engaging portion thereof. In turn, the tool is restricted by a stop with adjustment shims so that it cannot swing backward into contact with the adjacent portion of the angle beam when in its defined neutral position. Thus, regardless of forces on the ripping tool, the resonant beam is able to swing to and fro in its resonant vibration when appropriately energized by the sonic generator, eccentric weight oscillator, or other means, and no possibility of clamping the beam exists.

With reference to FIGS. 1 and 2, the ripping tool assembly 10 is mounted at the rear of a more or less conventional tractor 12 supported on the spaced endless tracks 14 for motion in a forward direction determined by a conventional steering mechanism 16 accessible to an operator seated on a driver's seat 18, with suitable adjacent controls 20 to effect not only the steering but the application of power to the endless tracks from a conventional engine 22, and also energization of hydraulic pumps 38 and 74 connected to certain hydraulic elements of the ripping tool assembly 10, as will be described hereinafter.

A heavy plate is mounted at the rear of the tractor 12 to carry at laterally spaced and substantially parallel positions a pair of parallelogram units 26, each including a rigid upstanding leg 28 at the rear of the tractor, the tops and bottoms of which carry pivotally supported legs 30, 32. Legs 30, 32 extend rearwardly, to in turn pivotally support the upper and lower ends of a vertical rear leg 34 of each parallelogram unit 26 at their rear extremities. A double-acting hydraulic ram 36 is pivotally connected between the lower end of the rear legs 34 and the middle of the front legs 28 by a cross rod 31 and another cross rod, not shown, so as to effect a raising or lowering of the rear legs of the parallelogram unit upon application of hydraulic fluid from previously mentioned pump 38 when actuated by the machine operator.

Rigid cross members 40, 42 extend transversely between the rear extremities of the parallelogram units 26 at both top and bottom to mount centrally brackets 44, 46 with aligned substantially vertical pivot pins 48, 50. Pins 48, 50, extend through aligned holes in brackets 52, 54 which are joined rigidly to side plates 56 of the ripping tool assembly 10. Thus, the ripping tool assembly 10 can pivot about the generally upright axis defined by the pins 48, 50 to accommodate turning of the tractor 12.

The side plates 56 extend in spaced parallelism rearwardly from the supporting parallelogram units 26 and carry therebetween several elements, including a horizontal pivot pin 58 which supports a ripping tool 60 therefrom for pivotal motion in forward and backward directions. The ripping tool 60 has a substantially conventional configuration, with a long shank 60a extending substantially vertically downwardly from the supporting pivot pin 58 and a forwardly and angularly projecting tooth 60b at its lower extremity. As illustrated in FIG. 4, the front surface of shank 60a converges to form a centrally located vertical leading edge 60c that helps to cut through the earth. It may be mentioned at this point that while but a single ripping tool 60 is herein shown, a series of parallel tools can be suspended if desired, each having a similar configuration. When the parallelogram unit is lowered into an operative position, the tool 60 can extend as much as several feet into the underlying earth or other surface, as shown in FIG. 1, to provide the ripping action upon appropriate actuation of the tool driving apparatus and forward motion of the tractor, as will be described in detail hereinafter.

The ripping tool 60 is completely free to pivot forwardly into contact with the earth or other material to be worked upon, but, in accordance with the present invention, a stop member 62 with removable shims 63 is disposed between the side plates 56 of the frame, to limit its backward motion to a particular position to be described hereinafter, which will not interfere with normal machine operation.

The tool driving apparatus includes a resonant force transmitting member 64 in the form of an angle beam composed of solid steel or other resilient material and having a pair of straight integral legs extending in divergent paths at or near approximately ninety degrees from their point of juncture. The legs of angle beam 64 are preferably equal in length and the vertical end thereof is enlarged in thickness, as illustrated in FIG. 1, to increase the mass at the region of impact with ripping tool 60. Stop member 62 comprises a rigid bar fixed to side plates 56 of ripping tool assembly 10 between ripping tool 60 and the rest position of the vertical end of resonant member 64.

To mount the resonant angle beam 64, an integral ear 76 projects outwardly from the juncture of the legs of the angle beam so as to bisect the angle between the beam legs. As used herein the term "integral" means that the entire resonant member 64, i.e., the legs and ear 76, is cast or forged as a single unit in a one piece construction. Parallel plates 65 are attached as by welding to opposite sides of ear 76. Holes in the plates 65 aligned with the juncture of the beam receive stub shafts 66 welded or otherwise fixedly secured to the plates 65. The shafts 66 are pivotally supported in bushings 67, which are in turn mounted in hard rubber hubs 69 supported in the side plates 56. Thus, although a pivotal support is provided for the beam, it is somewhat flexible and in no way interferes with the resonant vibration of the resonant angle beam 64.

In operative diposition, the one leg of resonant angle beam 64 extends substantially vertically and has, at its lower extremity, a forwardly projecting portion which lies closely adjacent the rear face of the ripping tool 60 at its lower extremity, to provide, upon actuation, a repeated cyclical series of blows to the rear of the ripping tool, so as to drive the same repeatedly into the adjacent earth or other material. As shown in FIG. 4, the lower end of the resonant angle beam 64 has a transverse, i.e., lateral, dimension less than that of the adjacent ripping tool 60. Therefore, when earth has been dislodged by the tool, substantially no earth contact with the beam will occur. The earth is diverted outwardly by ripping tool 60 much as a mobile snow shovel pushes snow out of its path.

Means are provided to energize the resonant angle beam 64 to resonant vibration, and preferably takes the form of a sonic generator or eccentric weight oscillator 68, as shown in my copending application Ser. No. 973,161, filed on Dec. 26, 1978 herewith, the disclosure of which is incorporated fully herein by reference. Oscillator 68 is connected to the end of the horizontal leg of the resonant angle beam for actuation by a hydraulic motor 70 through a belt drive 71. Motor 70 is attached to one of the side plates 56, and fluidically connected to hydraulic pump 74 for actuation under control of the machine operator. Oscillator 68 is driven by motor 70 such that the eccentric weights rotate at or near the resonant frequency of angle beam 64, which typically is of the order of 100 cycles per second.

It is to be particularly noted that this form of resonant angle beam 64 has but a single central node, namely, at the beam juncture and ear 76 along a line bisecting the angle of beam 64, when the beam is supported so it is restrained from vibrating at the juncture as shown. The legs of the beam resonate about this single node, with anti-nodes at the ends of the legs. A relatively long lever arm is provided by each of the beam legs so that a considerable stroke, particularly of the lower end of the tool actuating leg, is produced without the necessity of a resonant member or beam of excessive longitudinal dimensions. For example, the cyclical reciprocating stroke with an angle beam having a leg length of no more than five feet can have an output amplitude adjacent the ripping tool of one inch or more. Further, the single node and the associated node support structure are spaced far from the ends of the beam in comparison to a straight resonant beam having two nodes, as disclosed in my above referenced copending application. This is important in a ripper, where the node support must have be above ground and the ripping tool must be underground. In addition, since the ends of the beam are at an angle to each other, the sonic generator is located in a plane displaced a substantial distance from the plane in which the tool is located, as illustrated in FIG. 1.

The weight of oscillator 68 urges resonant angle beam 64 to pivot or rotate about pin 58 in a clockwise direction, as viewed in FIG. 1. A stop member 78 is attached to side plates 56 and extends therebetween adjacent to the end of ear 76 in the path of its clockwise rotation, as viewed in FIG. 1. Removable shims 80 are mounted on the surface of stop member 78 facing toward ear 76. Stop member 78 is shimmed so that the end of resonant angle beam 64 adjacent to tool 60 is located in a desired position, usually so the upright leg thereof is vertical when the beam is in its neutral position. The neutral position of the beam is its position when at rest, i.e., when not resonating or being deflected.

When oscillator 68 is operating, it applies a reciprocating force to the end of the horizontal leg at or near the resonant frequency of angle beam 64. While resonant angle beam 64 resonates, the juncture of its legs, which is the single node, remains stationary and the end of its vertical leg reciprocates in forward and backward directions, striking tool 60 each time it moves forward in its reciprocating excursion. A changing gap is formed between the end of the vertical leg of resonant angle beam 64 and tool 60--as the vertical leg reciprocates in a forward direction the gap tends to close and as the vertical leg reciprocates in a backward direction the gap tends to open, disregarding the continuous forward movement of the frame.

Ripping tool 60 comprises a work tool that moves along through the soil, which comprises the work path. Ripping tool assembly 10 functions as a tool holder or carrier. Continuous unidirectional force is applied thereto by tractor 12 in a direction parallel to the work path. Oscillator 68 generates a reciprocating force, at least one component of which acts parallel to the work path. Resonant angle beam 64 comprises a force transmitting member, the end of its horizontal leg comprising an input to which the reciprocating oscillator force is applied, and the end of its vertical leg comprising an output from which the reciprocating force is transferred to the tool. The tool advances intermittently along the work path responsive to the continuous unidirectional force applied by tractor 12 and the reciprocating force applied by oscillator 68.

A minimum protective gap is established between the neutral position of resonant angle beam 64 and tool 60 by stop members 62 and 78. As a result, when tool 60 encounters an immovable object, which prevents its further advance, tractor 12 continues to advance until tool 60 abuts stop member 62. In other words, stop member 62 limits the backward movement of tool 60 so it cannot reach the neutral position of the beam output. Thus, the end of the vertical beam leg cannot become clamped by tool 60 when tool 60 encounters an immovable object, and destroy the components of the ripping tool assembly. In my referenced copending application a different way is disclosed for establishing a protective gap between the output of the beam and the tool when the tool encounters an immovable object, namely, the use of substantially more reciprocating oscillator force than the continuous unidirectional force provided by the mobile carrier. In a number of applications, however, requiring that the mobile carrier supply a very large continuous unidirectional force, such as a shovel bucket or a rock ripper, it is impractical to furnish sufficient reciprocating oscillator force to establish the gap in the manner described in the referenced copending application.

Recognizing that small variations in relative spatial position between components cannot be avoided in the manufacture and assembly of the components of ripping tool assembly 10, the length of the minimum protective gap is adjusted from machine to machine by shims 63 on stop member 62 and shims 80 on stop member 78. Instead of shimming both stop members 62 and 78, one or the other of these stop members alone could be shimmed to establish the minimum protective gap. In a typical example, the peak-to-peak excursion of the beam output might be 2 inches, and the minimum protective gap might be 1/4 of an inch, so that the power stroke of the beam output would be 3/4 of an inch. The minimum protective gap should be no larger than necessary to prevent cessation of resonance when the tool encounters an immovable object, because the larger this gap, the smaller the power stroke, i.e., the portion of the beam output excursion in which it contacts the tool.

If resonant angle beam 64 is driven at or near its resonant frequency without restraining the beam juncture from vibrating as disclosed herein, it has two nodes near its ends, as in the case of a straight resonant beam. Under some circumstances, it may be desirable to operate a resonant angle beam in this way, i.e., with two nodes, by supporting the beam at these two nodes, rather than at the beam juncture.

For an explanation of how stop members 62 and 78 protect ripping tool assembly 10, reference is made to FIG. 5, wherein the central horizontal line N represents the neutral position of the resonant angle beam 64, and more particularly the output thereof, and the dashed horizontal line S spaced thereabove, represents the rearmost position attainable by the ripping tool 60 when in engagement with stop member 62. The distance between N and S represents the minimum protective gap. The normal resonant swing of the output of the resonant angle beam 64 is represented by the solid line sine wave indicated at R. When the tool encounters a very hard material and can no longer advance, it moves against stop member 62, thereby limiting the excursions of the beam output to an amount equal to the minimum protective gap forward and backward of the neutral position, as represented by the dashed line sine wave R'. This limited excursion is enough to maintain angle beam 64 in resonance and accordingly prevent destruction of the assembly.

As shown in the described embodiment and particularly in FIG. 3, the short connection of the stub shafts 66 in the plates 65 provides a relatively weak support. Consequently, a slightly modified stronger mounting arrangement as shown in FIG. 6 can be utilized. As there shown, parallel side plates 82 are welded to an outwardly projecting ear 84 formed at the juncture of the legs of the angle beam 85 and extend adjacent the sides of the resonant angle beam 85 beyond its inner edge to support a tube 86 in aligned holes. Tube 86 in turn, carries a single shaft 88, mounted by bushings 90, and rubber hubs 92 in the side plates 94 of the frame. Tube 86 and beam 85 are fixed relative to shaft 88, which is rotatable in bushings 90 about side plates 94 of the frame.

When only one side of ear 76 is supported or restrained, as shown in FIG. 1 by stop member 78 and the output of angle beam 64 is not loaded, i.e., is not driving a tool that is engaging material to be cut, it has been discovered that the amplitude of resonant vibration at the output of angle beam 64 drops off substantially. When the other side of ear 76 is supported or restrained, i.e., ear 76 is clamped with respect to stop member 78, the full amplitude of resonant vibration of the output of angle beam 64 is maintained. When the output of angle beam 64 is loaded, it is believed that the reaction of the material being cut, transferred through the tool to the output of angle beam 64, will provide the necessary clamping action on ear 76, without necessity for support or restraint on the other side of ears 76. If that proves to be the case, the embodiment of FIg. 1, where only one side of ear 76 is restrained will provide an advantageous, automatic on-off control of the resonant vibrations, that is, vibrations will be at a low amplitude when the output of angle beam 64 is not loaded and will automatically rise to full amplitude when the output of angle beam 64 becomes loaded.

In the event that on-off control is not desired or the reaction of the material being cut does not effectively clamp ear 76, such clampings can be accomplished in the manner shown in FIG. 7. Specifically, brack 96 is attached to side plates 56 and extends therebetween adjacent to the end of ear 76 in the path of its counterclockwise rotation, as viewed in FIG. 1, i.e., on the side of ear 76 opposite to stop member 78. After shims 80 are mounted on the surface of stop member 78 to establish the minimum protective gap, plates or wedges 97 are inserted in the space between ear 76 and bracket 96 to clamp ear 65 tightly between stop 78 and bracket 96.

While the tool driving apparatus has been described specifically in connection with a ripping tool, it will be apparent that it can also be applied to a cutter blade as of the type generally shown in my prior application referred to hereinabove, and also to a shovel bucket as disclosed in my application Ser. No. 25,484 filed on even date herewith, which is incorporated herein by reference, an article forming die, or other members of various types requiring considerable force in their operative functions. Consequently, the term "tool" is to be broadly construed.

The described embodiment of the invention is only considered to be preferred and illustrative of the inventive concept; the scope of the invention is not to be restricted to such embodiment. Various and numerous other arrangements may be devised by one skilled in the art without departing from the spirit and scope of this invention. For example, some of the advantages of an angle beam could also be realized by driving the force transmitting member non-resonantly or by driving it resonantly without restraining the juncture so that two nodes are formed, one one either side of the juncture. Although the angle beam has straight legs as shown in the drawings, in some embodiments it could have other bent configurations that exhibit a single centeral node when the beam is restrained at such node.