Earth auger

[0001] This invention pertains to an earth auger and, more particularly, to an auger having a flight with a plurality of earth-penetrating teeth spirally positioned thereon.

[0002] Various earth augers have been designed for drilling holes through strata of various materials. Past designs have used spiral flights for earth penetration. Some devices have added cutting teeth which were said to enhance drilling.

[0003] One disadvantage with such augers is that the tooth configuration, the teeth spacing and their surface drag all have a negative effect on the efficiency of the drilling process. Past auger designs have allowed for soil build up between the teeth which can diminish, if not cease, the drilling action. Also, the teeth of previous augers simultaneously engaged the ground in the same plane which presents an inefficient scraping action, undesirable drag and instability, all which further diminish the drilling action. Moreover, past teeth were not relatively positioned so as to provide a pneumatic drill-type action on the earth during the drilling process.

[0004] Accordingly, it is desirable to present an effective auger which avoids these past problems so as to enhance the drilling process.

[0005] In response thereto I have invented a novel auger design. My auger design includes an axial shaft/shank having a spiral cutting flight wound therearound. The flight begins adjacent the initial penetration point of the shank and spirally winds about the shaft towards the opposed end of the shank. The initial portion of the cutting flight presents a plurality of conical cutting teeth which are spirally displaced from the shank to provide a succession of single earth penetrating cuts, i.e., each tooth engages the underlying surface prior to engagement of an upstream tooth. The teeth are radially and longitudinally spaced relative to the shank such that an imaginary line extending through the teeth defines a spiral cutting edge which cooperates with the subsequent upstream cutting edge of the spiral flight. Thus, a corkscrew drilling effect is presented. The teeth are positioned, relative to each other and a horizontal plane normally passing through the axial shank, such that a pneumatic drill type action is directed onto the earth while preventing earth buildup between the teeth. Such relationships present a discrete stair-stepped pattern of earth removal with the pneumatic effect of the teeth first weakening the tiered earth and then fracturing each tier for effective removal. Each subsequent tooth cuts an earth relief for the housing of the preceding teeth so as to preclude drag of the preceding teeth housing on the earth. The plurality of teeth extend 360° about the shaft which further enhances the drilling action.

[0006] Accordingly, it is a general object of the invention to provide an improved earth auger.

[0007] Another object of this invention is to provide an auger, as aforesaid, having an earth cutting spiral flight wound therearound with a plurality of earth penetrating teeth forming a portion of the spiral flight.

[0008] A further object of this invention is to provide an auger, as aforesaid, wherein the teeth are easily replaceable within their respective housings.

[0009] Another object of this invention is to provide an auger, as aforesaid, wherein the teeth extend at least 360° about an axial shank.

[0010] A further object of this invention is to present an auger, as aforesaid, wherein the teeth are radially spaced, relative to an imaginary central axis of the shank, so as to preclude earth build up between the teeth during the drilling action.

[0011] Another object of this invention is to provide an auger, as aforesaid, wherein the teeth are vertically spaced so as to provide a single cut, corkscrew drilling action.

[0012] A still further object of this invention is to provide an auger, as aforesaid, wherein the teeth are spirally, vertically and radially spaced so as to provide discrete stair-step tiers for earth removal during the drilling action.

[0013] Another object of this invention is to provide an auger, as aforesaid, wherein the teeth are positioned, relative to the earth, such that a pneumatic drill-type or chatter action is provided against the underlying earth.

[0014] Another object of this invention is to provide an auger, as aforesaid, wherein the aforesaid pneumatic and corkscrew actions enhance the drilling process.

[0015] A still further particular object of this invention is to provide an auger, as aforesaid, wherein the spiral flight presents a spiral cutting edge first presented by the plurality of teeth, as aforesaid, and then a spiral cutting edge.

[0016] Another particular object of this invention is to provide an auger, as aforesaid, wherein the auger design stabilizes the auger during the drilling action to preclude undesirable auger movement.

[0017] Other objects and advantages of this invention will become apparent from the following description taken in connection with the accompanying drawings, wherein is set forth by way of illustration and example, a now preferred embodiment of my invention.

[0023] Turning more particularly to the drawings, FIG. 1 shows my auger 100 as generally comprising an axial shaft/shank 200 with a spiral flight 300 wound therearound. An upstream portion of the spiral flight 300 presents a continuous cutting edge 310. Along the downstream end of this spiral flight 300 are positioned a plurality of housings 400A-400I for holding Tungsten® carbide teeth 500A-500I in a spiral winding about the shank 200. A plurality of initial earth penetrating bits 600 are positioned at the end of the shank 200 with a scraper tooth 610 (phantom line) positioned along the shank 200. Bits 600 are used for initial earth penetration in a conventional manner with scraper tooth 610 keeping the earth moving away from the shank 200 during the auger operation.

[0024] My preferred embodiment herein is discussed in connection with a 16-inch auger although the principles disclosed herein can be utilized with larger or smaller augers. A plurality of housings 400A-400I present pockets for releasable engagement of the corresponding conical teeth 500A-500I therein. These housings are spirally embedded along the initial portion of flight 300 and present teeth which form the initial cutting surface of the spiral flight 300. The housings 400 begin adjacent the penetrating end of the shank (4″D), i.e., 400A, and terminate with the upstream housing 400I. Subsequently, the spiral flight 300 continues beyond housing 400I and presents a continuous spiral cutting edge 310. Each housing includes a bottom wall 411 and a tooth wall 413 with aperture 415 therein. The shank 515 of each tooth fits within aperture 415 and is releasably held therein by a compression ring. Each tooth 500 preferably extends from the housing at an approximate 30° angle relative to a horizontal plane normal to the axis of shank 200. Moreover, the housings are angled relative to this imaginary central axis of the shank 200 so that an imaginary line passing through the initial penetration point 520 of each tooth 500 present a spiral edge beginning at 500A and continuing through tooth 500I. This spiral line presents a spiral cutting edge as presented by the plurality of teeth 500A-500I. This spiral cutting edge then continues in alignment with the subsequent continuous cutting edge 310 of the upstream portion of spiral flight 300.

[0025] The housings 400 are further radially positioned, relative to the shank 200, such that a plurality of circular contiguous cutting paths, relative to the shank 200, are presented by each tooth.

[0026] Each tooth 500 presents a conical-shaped configuration with an initial penetration point 520 conically tapering to an enlarged circular base 514 having a diameter of approximately three-fourths of an inch. The points 520 of teeth 500 are preferably radially spaced at one-half inch intervals from the shank 200 with tooth 500A initially being two inches therefrom. Tooth 500I is thus slightly more than eight inches from the center of the shank 200 so as to present an approximately 16-inch hole upon drilling during earth removal (FIG. 5). The circular cutting paths of adjacent teeth 500 overlap. This overlap precludes undesirable material build up or ridges between the teeth 500.

[0027] Also, the angle of each tooth 500, relative to a horizontal plane, is positioned such that each tooth 500 chatters or reciprocates when contacting earth or rock. I have found one preferred angle to be approximately 30°. This chatter creates a pneumatic drill-like effect on the rock which first weakens and then fractures the rock. Angles, significantly less or greater than 30° may cause the teeth to drag across the rock. This resulting drag inhibits chatter, drill rotation and effective rock removal.

[0028] The vertical displacement between adjacent teeth 500 points 520 are preferably one inch. The vertical one inch tooth 500 displacement coupled with the one-half inch radial tooth 500 displacement presents successive stair-stepped configurations of earth removal with a one-inch riser 1610 and a one-half inch tread 1612 as shown in FIG. 5. These dimensions of the stair-step configurations allow the rock to be more effectively removed during the drilling process. Moreover, the spiral configuration of the teeth 500A-500I presents a corkscrew effect such that the weight of the device 100 is directed onto each tooth 500 as it is making a single cut into a selected stratum. Thus, rock drilling is enhanced.

[0029] The housings 400, being oriented to position the teeth 500 as above described, may extend beyond the cutting path of its housed tooth 500. However, the relationship of the cutting teeth 500A-500I with the housings 400A-400I provides a drilling advantage as each subsequent tooth 500 cuts a relief into the rock such that the housing 400 of the preceding tooth 500 will not drag along rock. For example, the point 520B of tooth 500B extends below the lowermost wall 411A of the preceding housing 400A for tooth 500A. The cutting path of this tooth 500B thus removes rock positioned in its path prior to housing 400A passing through this tooth 500B path. Thus, these tooth/housing relationships assure there is no drag of a preceding housing along the earth. It is noted that tooth 500I, being beyond the eight inch radius relative to shank 200, cuts a relief for the cutting edge 310 of flight 300 and its own housing wall 411I.

[0030] During auger operation, bits 600 form an initial four inch hole 1600. The teeth 500A-500I, as above described, form a circular stair-step configuration such that a series of one-inch risers 1610 and one half inch treads 1612 are being successively presented. It is understood that these stair steps are radially displaced from the hole center as successive teeth penetrate the ground. The formation of the riser 1610 weakens the rock underlying the horizontal ledge 1612 such that the rock is more easily fractured, chipped and/or removed by the subsequent pneumatic-like chatter action of the teeth on the rock. As the spacing of the teeth 500, as above described, precludes rock formation between teeth and the earth has been previously weakened by the pneumatic chatter effect, the rock is more easily removed during auger operation. Thus, I have found that this auger design increases the speed of auger rotation as more teeth 500 get into the rock unlike in previous devices.

[0031] As the last tooth 500I is slightly positioned beyond an eight inch radius from the centerline of shank 200, this tooth 500I forms a relief for its own pocket housing 400I as well as for the subsequent cutting edge 310 of the spiral flight 300.

[0032] As above, the angle of each housing 400 and thus its tooth 500, relative to the vertical centerline of shank 200, changes as each housing progresses along the spiral path. (The tooth angle, relative to the horizontal, is maintained to maintain the chatter effect.) As above described this angular change helps maintain the pneumatic action on the rock and presents a spiral or “corkscrew” succession of cutting teeth 500A-500I onto the rock. Also, the spiral configuration of the teeth 500 forms the hole from the outside diameter to the center as opposed to other augers wherein the hole is formed from the center towards the outside. As above the weight of the auger 100 is thus directed onto only one cutting tooth passing through one cutting path along the extent of the spiral, i.e., a “single cut” action. This additional weight onto the “single cut” action enhances rock removal. Moreover, as only one tooth at a time is contacting the rock in a respective tooth cutting path, significant drag is eliminated as compared to a double cut auger wherein two or more teeth are being dragged through the same path. This spiral configuration is also effective when cutting through discrete layers of rock. For example, when a preceding tooth cuts through a hard rock layer and into softer earth therebelow the weight of the auger is then transferred to upstream or preceding teeth which are penetrating harder rock layers. This weight transfer enhances drilling. Also, the spiral penetration of the teeth into the earth stabilizes the auger 100 so as to preclude undesirable shifting away from the hole center.

[0033] Accordingly, my auger design, presenting the above advantages, provides an effective auger for enhanced removal of earth whether through the earth, rock or any other strata.

[0034] It is to be understood that while a certain form of this invention has been illustrated and described, it is not limited thereto, except in so far as such limitations are included in the following claims and allowable equivalents thereof.