US2709573A

US2709573A - Earth auger

Info

Publication number: US2709573A
Application number: US213902A
Authority: US
Inventors: Forrest E Reed
Original assignee: Individual
Current assignee: Individual
Priority date: 1951-03-05
Filing date: 1951-03-05
Publication date: 1955-05-31
Anticipated expiration: 1972-05-31

Description

ma ma F. E. REED EARTH AUGER Why M a";

Filed March 5, 1951 JIVVENTOR.

Fmnnssv E. REED BY I United. States Parent 6 EARTH AUGER Forrest E. Reed, Bellevilie, ill.

Application March 5, 1951, Serial No. 213,902

1 Claim. (Cl. 255-69) This invention pertains to earth angers such as are used to (ig post holes for telephone poles and the like.

Generally stated, the invention involves improvements in the bit which is formed with a pair of i'lights armel at their Cutting ends with hardened renewable cutters of improved shape, and a fish-tail tip or pilot cutter which is also renewable. The tip is secured to the body of the bit in a novel manner so as to be supported against side strains tending to break oil the tip.

An illustrative embodiment of this invention is shown in the accompanying drawing, in which Fig. l is a side vi w of an auger bit embodying this invention, with part in section, the bit being shown in inverted position relatively to that assumed when in use;

2 is a top end view of Fig. 1;

Fig. 3 is a detail section on line 3-3 of Fig. 1;

Fig. 4 is a bottom view of Fig. 1, showing the mounting socket of the bit, to a reduced scale.

Referring to the drawing, the body of the bit com prises a steel casting formed with an axial shank l and two flights 2 extending radially in opposite directions from the shank 1. The forward end of the shank 1 has removably mounted therein, as by a threaded shank 3, a pilot tip 4 which may be a steel casting of fish-tail form having hardened cutting flights 5. In view of the fact that Fig. 1 shows the auger bit in inverted position, that is, with its tip up, while in use of course, the tip extends downward, and the terms top and bottom. upper and lower will be used to refer to the device in the position it is in use when digging a hole; that is, with the tip down. Also the terms forward and rearward refer to directions of movement, the forward movement of the bit as a whole being downward as it digs, while the forward direction of rotation is clockwise, as seen from above the bit when in use.

Each of the flights 2 is provided at its forward or entering end with a renewable cutter 6. This cutter is secured to the flight by bolts 7, or other suitable fastenings so as to extend in continuation of the flight and suw stantially in alinement with the end portion thereof to which it is attached, as shown in Figs. 1 and 3. Each cutter 6 is hardened along its cutting edge so that it may have a long life between replacements. The upper face of the cutter is also formed with a concave surface as indicated at 8 (Fig. 3).

The flights 2 are formed with a pitch which increases progressively from the front end to the rear end of the bit. This also provides for gradually increasing the velocity of movement of the cut material and provides increasing volume between the flights as the material becomes looser in its movement back along the bit. The outer edges of the flights 2 are also hardened, so as to withstand the wear incident to the boring operation.

Great difiiculty has been experienced heretofore in mounting a tip, such as 4', so as to be safe against breakage. When the tip strikes a hard rock displaced laterally from the axis of the hole being bored, the side strain often breaks oil the shank 3. In accordance with this invention, therefore, the threaded shank 3 of the tip threaded into a socket 19 in the body of the bit. The

terminal opening of this socket is bored smooth for a short distance and the shank 3 is formed with a collar ii at its junction with the tip 4. This collar 11 is fitted to the bore of said terminal opening closely enough to require a definite, though moderate pressure to force it into said bore. It may be given a slight taper. When assembled. it is screwed in against such pressure until the face ill. of the tip contacts firmly with the engaging face ot the body. When so seated, the end bore of the socket ltl provides a lateral support for the collar 11 to absorb side shocks and prevent them from being transmitted to the threaded portion of the shank 3. The thread of the shank may be terminated short of the root of the shank (where it joins the tip 4) as shown at 3a in 1 so that stresses due to such side shocks are removed from the terminus of the thread which is usually the weakest part of the shank.

The upper end of the body shank l is formed with a mounting socket 13, usually angular in form, to receive the driving element of the boring machine. A transverse hole 14 may be provided to receive a cross pin for retaining the bit in place. Most machines provide a spring on this driving element against which the bit strikes when elevated to the limit of its travel, the impact serving to dislodge the dirt from the bit. in order to take this impact the present invention provides that the flights 2 are continued to the upper end of the socket 13, their ends being flush with the ends of the socket. The webs of the flights are also thickened where they join the wall of the socket as indicated at 15. This provides a broadened surface of metal, symmetrical about the bit axis, to take the impact.

it will be seen, therefore, that this invention provides an anger which is inexpensive. though sturdy, and which can be maintained in good working condition with little trouble or expense. The renewable cutters of special shape are quickly changeable when worn. Their shape and that of the flights is such as to remove the earth easily and with a minimum expenditure of power.

Various changes may be made in the details of construction, within the scope of the appended claim, without departing from the spirit of this invention. Parts of the invention may be used without the whole and improvements may be added while retaining some or all of the advantages of this invention.

I claim:

An earth auger comprising, a body formed with a central shank, a pair of oppositely extending helical flights integral with an progressing along said shank, said shank being formed with a threaded tip receiving socket at its lower end and a mounting socket at its upper end, a pilot tip, a shank on tip threaded to fit said threaded socket and having a supporting collar at its junction with said tip, said collar being fitted to a pressure fit with the bore of the terminal openin of said tip socket, each of said flights having a pitch increasing progressively from its entering end rearward, 3.: a renewable cutting bit detachably mounted on the entering end of each of said flights.

References Cited in the tile of this patent UNITED STATES PATENTS 76.188 Heath Mar. 31, 1868 558,994 Snyder Apr. 28, 1896 1,376,224 Paszko Apr. 26, 1921 1,466,378 McLaughlin Aug. 28, 1923 1,849,510 Thomson Mar. 15, 1932 2,201,159 Clow May 21, 1940 2,239,461 Mann Apr. 22, 1941 2,613,062 Herbert Oct. 7, 1952 FOREIGN PATENTS 248,839 ltaly June 18, 1926