Resonant Tool Driving Apparatus With Tool Stop

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. 973,161, filed on even date herewith, is described tool driving apparatus in which one extremity of a 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. 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. To prevent destruction of the tool driving apparatus when the tool encounters an immovable object, i.e., an object that the oscillator force is unable to overcome, a protective gap is held between the neutral output position of the resonant beam and the tool. Specifically, the force of the sonic generator is sufficiently large relative to the unidirectional force to overcome the latter, and to drive the tool holder back away from the tool when the tool is unable to advance along the work path, thereby establishing the protective gap.

A sonic generator produces a reciprocating force that is transmitted to a tool by a resonant or nonresonant force transmitting member having an output that reciprocates in forward and backward directions about a neutral position responsive to the force of the sonic generator. The tool is located forward of the output of the force transmitting member, and is movable in backward and forward directions along the work path. A changing gap is formed between the tool and the output as the output reciprocates, the gap tending to close and strike the tool as the output reciprocates in a forward direction and tending to open as the output reciprocates in a backward direction. A continuous unidirectional force is applied to the force transmitting member. The tool advances intermittently along the work path through the material being processed responsive to the continuous unidirectional force and the reciprocating force. According to the invention, a protective gap is maintained by a tool stop between the tool and the output of the force transmitting member, independent of the relative magnitude of the force of the sonic generator and the unidirectional force. The tool stop limits the backward movement of the tool so it cannot reach the neutral position of the output.

According to a feature of the invention, the tool stop and/or the supports for the force transmitting member are shimmed to precisely set the protective gap width.

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; and

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

Accordingly, it is the objective of the present invention to provide a tool driving apparatus employing 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 member 64 in the form of an angle beam composed of solid steel or other resilient material and having a pair of integral legs extending in divergent paths at approximately ninety degrees from their point of juncture. 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. 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. To 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 disposition, 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 even date 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 (by means not shown) 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.

It is to be particularly noted that this form of resonant angle beam 64 has but a single node, namely, at the beam juncture and ear 76 along a line bisecting the angle of beam 64, when the beam is held at the juncture as shown. The legs of the beam resonate about this single node. 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 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 longitudinal 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. Thus, stop member 78 rigidly supports resonant angle beam 64 with respect to ripping tool assembly 10 during operation as to all motion except resonant vibration.

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 longer 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 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.

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 or other members of various types requiring considerable force in their operative functions. Consequently, the term "tool" is to be broadly construed.

Accordingly, the foregoing description of an embodiment is to be considered as purely exemplary and not in a limiting sense, and the actual scope of the invention is to be indicated only by reference to the appended claims.