US3053331A

US3053331A - Excavating device

Info

Publication number: US3053331A
Application number: US848383A
Authority: US
Inventors: Gale C Corley
Original assignee: Individual
Current assignee: Individual
Priority date: 1959-10-23
Filing date: 1959-10-23
Publication date: 1962-09-11
Anticipated expiration: 1979-09-11

Description

Sept 11, 1962 G. c. coRLx-:Y 3,053,331

EXCAVATING DEVICE Filed 001).- 25, 1959 United States Patent Otllice 3,@533l Patented Sept. l1, 1962 3,053,331 EXCAVA'HNG DEVIQE Gale C. Corley, 1207 Beech St., Valparaiso, lind. Filed Oct. 23, 1959, Ser. No. 848,383 5 claims. (ci. 1175-202) This invention relates to an improved earth underreamer for use in reaming the lower portions of previously excavated holes or bores so that an enlarged base or footing may be provided under poured concrete foundation piers, pilings, posts or the like.

In certain types of construction it is common practice to use concrete columns which extend below grade level as foundation supports for beam structures. Good engineering practice and some building codes require that the bottom of such columns be enlarged to provide proper support and prevent foundation settlement. Although various types of underreamers have been proposed to perform this worlr, they have been found to embody unduly complex and costly structures and to suffer from such problems as clogging in retraction, diiicult actuation of the cutters, and high torque requirements at extended positions of the cutters. As a result, it has been common practice to enlarge holes for foundation supports by primitive hand spades and this has been costly because of the hand labor required.

Accordingly, it is an object of the present invention to provide an improved underreamer having adjustable excavating means for the graduated enlargement of a lower portion of a pre-bored foundation hole, which may be readily lowered into and withdrawn from the hole without interference from the excavating means and yet which will excavate a shaped underfooting cavity having a large diameter in proportion to the diameter of the prebored hole.

Another object is to provide a hollow underreamer adapted to receive and store the excavated material, which will not join in heavy wet soil or clay when it is desired to retract the exacavating means, and from which the excavated material may be easily unloaded after the underreamer is removed from the bore hole.

A further object is to provide an underreamer having excavating means positively actuated in both the expanding and retracting directions and which may be locked in a plurality of graduated positions easily observable by the operator, and in which the amount of back torque being exerted on the excavating means during the cutting operation tends to remain constant for such positions.

Still another object of the invention is the provision of a strong underreamer having a minimum of parts and which is very simple and economical to construct.

A feature of the present invention is the provision of an underreamer having excavating means in the form of a combined cutting and deflecting member including a base portion, which may be formed in the shape of a quarter section of a circle, and a scoop portion mounted on the circular edge thereof. The base portion is pivotally mounted at its vertex in a horizontal position offset from the center of the casing so that the cutting member is rotatable through an opening in the side of the underreamer casing to a plurality of extended cutting positions.

Another feature is the provision of an underreamer having a single cutting member pivotally mounted on an axially offset longitudinal rod which extends the length of the casing and to which a crank arm or handle is pivotally attached at the upper end of the rod to provide leverage for directly actuating the cutting member. The pivotable handle may be positioned in notches provided in the upper rim of the casing to lock the cutting member in a plurality of positions, thereby providing an easily observable indication of the setting of the cutting member at all times.

A further feature of the invention is the provision of an underreamer having a cutting member of the aforesaid character with a cutting edge both on the leading edges and on the trailing edges thereof so that it slices back into the fully loaded casing With a minimum of effort.

A still further feature is the provision of an underrearner having a cutting member driven by rotating the hollow casing so that it is capable of transmitting high torsional forces without cluttering the interior of the casing with driving apparatus obstructive to the entrance and storage of excavated material.

Still another feature is the provision of an underreamer adapted for power operating and having helical guiding means, such as a spiral auger, iixedly mounted in the hollow casing to facilitate the elevation and storage of the excavated material during the cutting operation, and an annular flange mounted around the top of the casing to seal the top of the hole and to lock the positioning handle in visible positions.

Yet another feature is the provision of an underreamer having a trap door in the bottom thereof to facilitate emptying the underreamer and which is locked by retracting the cutting member and is therefore controlled by actuating the positioning rod.

The invention is illustrated in the accompanying drawing in which:

FIG. l is a perspective view of an underreamer constructed in accordance with the invention;

FIG. 2 is a fragmentary perspective view of the lower portion of the underreamer illustrating the manner in which it operates in a pre-bored hole;

FIG. 3 is a bottom plan view of the underreamer;

FIG. 4 is a fragmentary elevational view of a lower portion of the underreamer taken in section on line 4 4 of FIG. 3; and

FIG. 5 is a perspective view of another embodiment of the invention adapted for operation by a power driving unit.

An underreamer provided in accordance with the invention includes a hollow, elongated cylindrical casing having a cutting member retractable therein. The cutting member includes a vertical scoop-like blade mounted on the circular edge of a horizontal radial blade, the latter being connected at its vertex to a positioning rod so that the cutting member is pivotable through an opening provided in the side of the casing. The longitudinal positioning rod is pivotally mounted along the side of the casing. A handle is pivotally connected to an upper portion of the positioning rod for positively actuating and positioning the cutting member located at the bottom of the casing. The bottom of the casing is enclosed by a plate having a hinged trap door therein which is latched by actuating the cutting member. In a power driven embodiment of the invention a spiral auger is mounted within the casing to elevate excavated soil, and an annular flange is fastened to the upper edge of the casing to prevent the elevated soil from spilling into the bore hole. A plurality of spaced pegs or lugs mounted on the upper surface of the flange receive and lock the handle in various visible positions, while a plurality of notches in the upper edge of the casing may serve this function when the flange is not used.

Referring now to the drawing, FIG. 1 shows an underreamer embodying the invention and adapted for hand operation. A hollow casing 11 shaped in the form of an elongated cylinder is provided having7 a suitable diameter and length to slidably fit within a pre-bored hole of a given size. The casing should be tall enough to extend a sufficient distance above the surface of the earth to permit convenient hand operation. A pair of opposite holes 12 are located near the upper end of casing 11 to receive a pipe or bar 13 for use in rotating the casing by hand. The upper end of casing 11 is left open while the lower end of the casing is enclosed by a circular bottom plate 14.

An excavating or cutting member consisting of a horizontal blade portion 16, shaped generally in the form of a sector of a circle, and a vertical scoop-like blade portion 17, is rotatably mounted inside the casing adjacent bottom plate 14. The side of casing 11 adjacent the excavating member is cut out so that an opening 1S is provided of a size and shape to permit the excavating member to pivot therethrough (FIG. 2). Cutting edges, such as knife edge 19, are provided on the leading and trailing outwardly extending edges of blade portion 16 as indicated at 16a and 16b (FIGS. 1, 2 and 3). Similarly, cutting edges are provided at the leading edge 17a and the trailing edge 17b of the scoop-like blade portion 17.

The vertex of blade 16 is secured to the lower end of a vertical shaft or rod 21 which is pivotally mounted on bottom plate 14 near the inside surface of the casing and which extends longitudinally to the top of the casing. The upper end of rod 21 is rotatably mounted in a suitable bearing bracket 22 welded to the inner wall of the casing. An upright arm 23 is fastened or welded to the' upper portion of rod 21 to pivotally support a handle 24. A portion of the upper edge of casing 11, disposed generally opposite bracket 22, is cut into a plurality of spaced notches 26 which are adapted to receive and position handle 24.

As may be more clearly seen in FIGS. 3 and 4, the bottom plate 14 is divided into two portions; a rigid portion 14a welded to the inside wall of casing 11 and a larger portion 14b pivotally secured to portion 14a by a pair of hinges 27 to form a trap door opening downwardly from the bottom of casing 11. Trap door 14b carries an L- shaped lug 28 welded to its upper inside surface at a point where it will be engaged by `a wedge Z9, fastened to the bottom outside edge of blade 17, in the fully retracted position of the cutting member.

In operation, a conventional post hole digger or other hole drilling equipment is employed to dig a hole of the desired depth and diameter. Then an underreamer, constructed to t this hole and embodying the structure of the invention, is lowered into the pre-bored hole. The

cutting member blades

16 and 17 are fully retractable within casing 11 (FIG. l) so that it can bear against the sides of the hole and thus serve as a guiding sleeve for accurate underreaming. Pipe handle 13 may be centered in casing holes 12 to provide handles on either side of casing 11 for lowering the underreamer into the hole.

With the casing bottom plate 14 resting against the bottom of the hole, the blades of the cutting member are extended through opening 18 so as to bite into the earthen side wall of the hole. Extension of the cutting member is accomplished at the upper end of the casing by merely lifting handle 24 upward out of a notch 26 and moving it clockwise, causing rod 21, horizontal blade 16 and scoop blade 17 to rotate clockwise. It will be seen that the plurality of spaced notches in cooperation with handle 24 provide a graduated locking mechanism for the cutter. If a shallow cut is desired, then handle 24 is dropped into the next adjacent notch, thus locking the cutting member in a slightly extended position coresponding to this notch setting. This setting is used, for instance, in hard soil or clay. Then casing 11 is rotated one complete revolution in a clockwise direction, as indicated by the arrows in FIG. 1. Since the excavating mechanism is non-rotatably mounted with respect to the casing, the blades rotate with the casing. The material excavated from the side wall of the hole, commonly referred to as spoi1, is deflected into the hollow interior of casing 11 by scoop 17. Due to the fact that the casing itself is used for transmitting torque, there is a maximum amount of spoil storage space available within the casing.

After the rst cut has been made, the cutting member is further extended by moving handle 24 clockwise to the next adjacent notch, and the casing is rotated once more. This process is continued until the blades are fully extended (FIG. 2) and an underfooting cavity 30 is completely excavated. In loose soil, such as sand, larger bites are possible and therefore some of the intermediate notches and corresponding cutter setting need not be used.

It is to be understood that cutting members of various shapes and material may be provided for interchangeable use with the underreamer of the invention. In the disclosed embodiment, the horizontal'blade 16 has a leading knife edge 19. A similar shape is given to the leading edge of the scoop 17. In addition, scoop 17 is quarter cylindrical in shape, conforming to the outer edge of quarter circular blade 16 (FIG. 3).

Both members combine to form the correct geometric configuration to cut a bell-shaped cavity 30 at the bottom of the hole (FIG. 2). It is well known that an underfooting of this shape provides the greatest strength in proportion to its mass. Of course, other cavity shapes may be produced by varying either the shape of scoop 17 or the combined shape of blade 16 and scoop 17.

Since vertical scoop blade 17 pivots from rod 21 on a. center which is offset from the axial center of casing 11, the radius of horizontal blade 16 may be almost as large as the diameter of the casing. This makes it possible to excavate an underfooting cavity having a large diameter compared to the diameter of the pre-bored hole, thus effecting considerable savings in the amount of concrete needed to support a given weight. It is also to be noted that the angle of incidence of the leading edge of scoop 17 with the side of the hole is most abrupt or at its maximum when the cutting member is least extended.

When the cutting member is fully extended the leading edge of scoop 17 is approximately tangential to the periphery of the cavity. Thus the rake angle of the vertical blade Varies inversely with the depth of the cut, and consequently the back torque exerted on the cutting member by the material being excavated tends to remain constant.

Once the underfooting cavity has been completed, handle 24 is unlocked and returned counter-clockwise to its original position, thereby retracting the cutting member completely within the casing. The trailing edges of both horizontal blade 16 and vertical blade 17 are also sharpened to a knife edge so that they will easily slice into the spoil accumulated within casing 11. Retraction is further facilitated by the leverage provided by handle 24, another important feature when excavating in wet, heavy clay.

During the cutting operation trap door 14b is unlocked, but since it is resting on the bottom of the hole no spoil can escape. Then as scoop 17 is retracted, wedge 29 engages the L-shaped lug 28 to cam the door tightly closed. Hence, by locking the cutting member in the fully retracted position (by dropping handle 24 in the first notch), the operator automatically locks the trap closed. The casing is then lifted from the hole by means of handle 13 and rested on the xed bottom portion 14a. Trap door 14b may then be unlocked to dump the spoil by moving handle 2,4 clockwise one notch. Cooperation is thus achieved between the cutter actuating-locking mechanism and the trap door latch, with the operation and condition of both being readily indicated to the operator by the position of the handle 24 at the top of the casing.

In FIG. a modified underreamer in accordance with the invention is shown adapted for power operation. Those elements identical with the elements of the abovedescribed embodiment are given identical reference numerals and their description not repeated. A helicoidal guide or auger 31 is non-rotatably mounted within casing 11 to elevate spoil from the bottom to the top of the casing as the casing is rotated. A central shaft 32 is welded to the auger blades to support an adapter coupling 33 carried on the upper end of the shaft. The adapter coupling may also be braced by supporting legs 34. The chuck of a conventional portable air motor 36 is received in the upper end of the adapter coupling to power drive the underreamer.

A large annular flange 37 is secured to the upper edge of casing 11 to keep the elevated spoil from falling back into the excavated hole. A plurality of positioning elements, such as spaced pegs 38, are welded on the upper surface of the flange in lieu of the easing notches 26. Handle 24 is again pivotally secured to positioning rod 21, but now extends outwardly to be received and locked between pegs 38. The outer edge of the flange extends beyond the end of handle 24 so that it will not endanger the operator when the underreamer is rotating. Trap door 14 may also be provided on the bottom of the underreamer, but it need only be used for iinal cleaning of the underreamer since spoil is automatically ejected by the spiral auger. Since positioning rod 21 is normally disposed closely adjacent the inside wall of casing 11, there is no mechanism within casing 11 to interfere with the elevation of spoil. It will thus be seen that this embodiment possesses all the advantages obtained by the structure of the first embodiment, and only a few additional elements are necessary to readily convert the hand operated underreamer for efcient high speed operation.

I claim:

l. In an underreamer for excavating an underfooting cavity in a pre-dug hole, and which underreamer includes a vertically extending, hollow elongated cylindrical casing and means for rotating the casing in a given direction, and with the casing having an opening in its side with leading and trailing edges with respect to the given direction of rotation; the combination including longitudinally extending shaft means rotatably supported within the casing on a substantially vertical axis near the leading edge of the opening, a cutting member shaped to pass through the opening and having a horizontal portion generally in the form of a sector of a circle, with the apex thereof pivotally mounted on said shaft means and with cutting edges formed along both edges extending outwardly from the apex, said cutting member having a curved scoop portion extending vertically from said horizontal portion and disposed substantially in an arc spaced from said axis with cutting edges formed along the leading and trailing edges of said scoop portion, and means for rotating said shaft means to thereby pivot said cutting member so that said sector portion and said scoop portion travel through said opening with said scoop portion passing near the trailing edge of the opening, said cutting member when extending through said opening being positioned to undercut the pre-dug hole upon rotation lof the casing and being retractable into the casing for withdrawal of the casing from the excavation.

2. The combination of claim l further including helical guide means mounted inside the casing and extending through the length thereof, said guide means elevating spoil produced by said cutting member upon rotation of the casing.

3. In an underreamer having a vertically extending elongated hollow cylindrical casing adapted for rotation in a given direction, with the casing having an opening in its side having leading and trailing edges, the combination of a cutting member having a horizontal portion shaped substantially in the form of a sector of a circle and having cutting edges formed along both edges extending outwardly from the vertex thereof, said cutting member also having a scoop portion disposed vertically along the circular edge of said horizontal portion with cutting edges formed along the leading and trailing edges of said scoop portion, shaft means rotatably supported within the casing on a substantially Vertical axis near the leading edge of the opening in the casing, said horizontal portion of said cutting means being connected at the vertex thereof to said shaft means, means coupled to said shaft means for rotating the same to position said cutting member, said cutting member being movable to a position in which it extends through said opening and being retractable completely within the casing, and means for rotating the casing in the given direction whereby said cutting member when eX- tending through said opening undercuts a pre-dug hole in which the underreamer is placed.

4. An underreamer for excavating an underfooting cavity in a pre-sunk hole including in combination, a hollow, elongated cylindrical casing having an opening in its side near the bottom thereof, a plate enclosing the bottom of said casing below said opening, bearing means secured to the inside of said casing near the top thereof, a positioning rod extending the length of said casing and being rotatably supported by said plate and said bearing means in a position parallel to and offset from the axis of said casing, a cutting member having a horizontal blade shaped substantially in the form of a sector of a circle with cutting edges formed along both edges extending outwardly from the vertex thereof, said cutting member also having a vertical scoop blade secured to the circular edge of said horizontal blade with cutting edges formed along the leading and trailing edges of said scoop blade, said cutting member being secured to said rod at the vertex of said horizontal blade and adjacent said opening so that said cutting member is extendible and completely retractable through said opening, a handle pivotally connected to the upper end of said rod for actuating said cutting member, said casing having a plurality of spaced notches along the upper edge thereof adapted to receive said handle to lock said cutting member in a plurality of corresponding angular positions, said plate having a hinged trap door therein for emptying spoil from said casing, said scoop blade having a wedge portion on the yback side thereof, said trap door havinga locking portion adapted to -receive said Wedge portion so that said trap door is locked closed in rthe retracted position of said cutting member and means for rotating said casing in a given direction whereby Said cutting member undercuts the pre-dug hole when extended through said opening in said casing.

5. A power driven underreamer for excavating an underfooting cavity in a pre-sunk hole including in combination, a hollow, elongated cylindrical casing having an opening in its side near the bottom thereof, a plate mounted in said casing below said opening, bearing means secured to the inside of casing near the top thereof, a positioning rod longitudinally extending along the inner surface of said casing and being pivotally supported by said plate and said bearing means, a cutting member having a horizontal blade shaped substantially in the form of a sector of a circle With cutting edges formed along both edges extending outwardly from the vertex thereof and having a vertical scoop blade secured to the circular edge of said horizontal blade with cutting edges formed along the leading and trailing edges of said scoop blade, said excavating means being secured to said rod at the vertex of said horizontal blade and adjacent said opening so that the cutting member is extendible and completely retractable through said opening, a handle pivotally connected tothe upper end of said rod for actuating said cutting member, an annular ange secured to the upper edge of said casing and having a plurality of spaced lugs thereon adapted to receive said handle therebetween to lock said cutting member in a plurality of corresponding angular positions, said plate having a hinged trap door therein for emptying spoil from said casing, said scoop blade having a wedge portion on the back side thereof, said trap door having a locking portion adapted to receive said wedge portion so that said trap door is locked closed in the retracted position of said cutting member, means secured to the top of said casing and adapted to couple a power drive unit thereto for rotating said casing and a spiral auger References Cited in the le of this patent UNITED STATES PATENTS 207,122 Julien Aug. 20, 1878 1,905,995 Bertran Apr. 25, 1933 2,621,898 Brodhead et al Dec. 16, 1952 2,912,225 Kandle Nov. l0, 1959 2,912,228 Kandle Nov. 10, 1959