US 2800302 A
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Jufiy 23, 1957 Filed Jan. 23. 1952 M. MCCLENNAN AUGER HEAD 3 Sheets-Sheet l JNVENTOR.
July 23, 1957 M. MOCLENNAN 2,800,302
AUGER HEAD Filegl Jan. 23. 1952 INVENTOR.
July 23, 1957 Filed Jan. 23. 1952 M- M CLENNAN AUGER HEAD 3 Sheets-Sheet 5 'INVENTOR.
AUGER HEAD Morton MeClennan, Cleveland Heights, Ohio, assigner to The Austin Powder Company, Cleveland, @hio Application January 23, 1952, Serial No. 267,791
3 Claims. ((31. S--61) This invention relates to a tool or auger head for drilling holes in earth, or rocks and the like and more particularly to improvements in the construction or" such tools.
Auger tools which are used for drilling holes in earth or rock and the like are subject to inherent operating limitations which become more pronounced and restrictive as the density and hardness of the material which is drilled or bored increases. Some of these limitations cause vibration and heating of the auger to such an extent as to require increased maintenance and repair and extends the time of drilling beyond practical limits.
A principal difiiculty encountered in the operation of an earth auger relates to the difficulty in getting the auger started in the drilling of the material when the material is relatively hard. In some cases, pit coal mines have been abandoned because of the inability to pierce rock with the ordinary existing tools. Likewise, it has been necessary at times to abandon strip mining in a given area due to the inability of tools to drill the over burden in order to reach the pay material underneath.
Accordingly, it is an object of this invention to provide an improved construction for an auger tool which will reduce the operating limitations andenable it to penetrate hard materials without loss of efliciency or breakdown.
Another object of this invention is to provide a selfpiloting construction for'an auger tool which willcnable it to initiate the drilling operation in any material regardless of its density or hardness.
A further object of the invention ;is to provide an improved arrangement for removably mountingcutters in an auger tool to facilitate replacement and sharpening of the cutters in a minimum amount of time.
Briefly, in accordance with this inventionrthere isprovided anauger tool headhaving a rotatable body portion provided with a series of radial vanes which extend outwardly relative to the axis of rotation and Which have leading surfaces curved outwardly from and forwardly relative to the axis. Each of the vane .leading surfaces is stepped outwardly fromthe axis of rotation and rearwardly from the leading edge to provide reinforcing shoul- PQ Tii9nS contiguous witht-the :leading edge of each stepped ,portion. Each of thestepped portionson each vane leading surface is also spaced outwardly from the axis of ,rotation and downwardly from the leading vane surface at increasing distances progressing outwardly about; the axisof-rotationon successive vanestowardsthe outermost steprportions, and each is further provided with anaxially.tapered-aperture terminating within therespective Manes for removably ;receiving the complementary shanlcof acutter element therein. Each vane is further provided with through transverse apertures intersecting each tapered axial aperture within the auger head and each of which is adapted to receive a tapered punch whereby the shankextremity of'the cutter element may be-engaged thereby and pressed outwardly from the tapered receiving apertureto 'facilitate replacement.
ZSWBW Patented July 23, 1957 The individual stepped portions and their correspondingly tapered apertures and cutters are each inclined outwardly from the axis of rotation, at increasing multiples of a common incremental angle, progressing outwardly around the axis of the head from the innermost stepped portion through the next adjacent in radial distance to the outermost stepped portions. Preferably two of the outermost cutters are disposed at the same radial distance from the axis of the head, and preferably the maximum angle between the axis of the outermost cutter and the axis of the head is 30. This relationship tends to minimize drag on the cutter elements during the drilling operation. Each cutter element is also rotated about its individual axis slightly in the direction of rotation of the head to set its cutting face so as to insure that each cutter initiates an individual cutting operation in the material being drilled, and to insure that the inside corner is the leading part of the cutter.
In the drawings,
Fig. 1 is a side view of an auger head embodying the present invention;
Fig. 2 is an end view of the device shown in Fig. 1;
Fig. 3 is a side view illustrating the head attached to a modified drilling shaft with its axis of rotation in a horizontal plane;
Fig. 4 is a composite diagram illustrating the angular and vertical disposition of each of the cutter elements when rotated about the axis of rotation into a common P n Fig. 5 is a side view of a cutter element illustrating the inclination of the .element in the direction of rotation;
Fig. 6 is a side view of the auger head illustrating the relative disposition of the cutter elements thereonp Fig. 7 is an end View of one of the vanes of the device illustrating the spacing and disposition of the cutter elementson such vane;
Fig. 8 is an end view of the auger head showing the shouldered, stepped down vane leading surfaces with the cutter elements removed;
Fig. 9 is a partial view of a section taken through one of the vanes to illustrate the cutter mounting in such vane;
Fig. 10 is a view taken along lines 1tl-10 in Fig. 9;
Fig. 11 is a diagrammatic View illustrating the disposition of the cutter elements relative to each other'in a horizontal plane; and
'Fig. 12 is a diagrammatic illustration of the cutting profile of the auger head of this invention, illustrating the individual annular stepped-down formation.
Referring to Fig. 1 of the drawings, the augerhead it is shown removably coupled through a coupling member 11 to a rotatable drill shaft 12. The coupling is accomplished by providing the rear or shank end of the auger head 10 with a transverse keyway slot 13 which is adapted to receive an extended keyway guide portion 14 of the coupling member 11 in interlocking engagement. The removable coupling member 11 also has a central cylindrical extension 15 having a frustro-conical end portion extending axially from the keyway guide portion 14 into a cylindrical recess having a frustro-conical terminal located centrally in the rear or trailing end of the auger head 14) to provide a socket connection. Any wellknown form of locking mechanism, such as a transverse pin or key may be utilized to secure the coupling member 11 to the auger head 10 to further restrain axialrnOvement and rotation therebetween. The coupling member 11 may be fixedly carried at the end of the rotating drill shaft 12 or may be removably coupled to such shaft to transmit both rotation and axial thrustfrom the shaft to the auger head. i
The body of the auger head 16 is constructed with a plurality of radially spaced vanes which extend outwardly from the body and its central axis of rotation. In the preferred embodiment illustrated in the drawings, there are shown three such vanes 20, 21 and 22 whichare substantially equi-distantly spaced about the axis of rotation and each of which extends and curves outwardly and forwardly at its leading extremity relative to the axis and direction of rotation of the body which, as illustrated in the drawings, is adapted for right hand or clockwise rotation by the shaft 12. Each of the vanes also slope or curve axially toward the shaft and rearwardly relative to the axis and direction of rotation of the head, so that the material removed by the cutter elements carried by the leading portion of the head may readily pass upward between the warms, to be carried away by a spiral flight or rib 17 that may be provided on the drill shaft 12 as shown in Fig. 3.
As best shown in Figs. 2 and 8 of the drawings, each of the leading vane surfaces 23, 24 and 25 along the axial extremities of the vanes is stepped outwardly from the axis and downwardly toward the shaft at progressive uniformly increasing radial (a) to (f) and axial (g) to (k) distances respectively from the innermost stepped surface around the axis on successive vanes towards a pair of outermost stepped surfaces and 36 on successive vanes 22 and 23 each of which have substantially the same radial and axial disposition. Each step on the leading vane surface is also stepped downwardly from the leading or forward edge of the vane and rearwardly relative to the direction of rotation to provide individual reinforcing shoulder portions 39 contiguous with the corresponding leading vane edge at each stepped portion.
The individual stepped portions 30 to 36 are each preferably machined to provide a flat surface which is inclined forwardly into the direction of rotation and outwardly from the head axis and which may be readily drilled to provide receiving apertures 40 to 46 for cutter elements 50 to 56. The apertures may be drilled in each stepped portion of a given vane leading surface along a relatively straight line from the head axis so that the auger head 10 may be mounted in relation to the drilling tool in such manner that it is merely necessary to rotate the auger head about a transverse axis and in a direction parallel with the leading vane surface being drilled. The drilling tool should be set to conform to the forward inclination of each vane, whereby the apertures are drilled at a forward 'angle of approximately 12 to hold each of the cutter elements 50 to 56 so their cutting edges are inclined into the direction of rotation of the auger head as best shown in Figs. 5 and 6 of the drawings.
In accordance with the preferred embodiment of this invention, the individual step portions 30 to 36 in the respective leading vane surfaces are also formed to individually incline outwardly at obtuse angles with the axis of rotation of the head so that the axis of each individual aperture 40 to 46 is inclined outwardly from the axis of rotation at increasing multiples of a common incremental acute angle progressing from the innermost step portion 30 through the next adjacent 31 in radial distance from the axis of rotation to the outermost step portions 30 and 36. The common incremental angle should be chosen so that the axes of the apertures in the successive outermost step portions 35 and 36 are within a maximum angle of inclination relative to the axis of rotation of approximately 30 in order to minimize drag on the cutter'elementsduring the drilling operation, as will be hereinafter more fully described in connection with Fig. 4 of the drawings.
Referring now to Fig. 4 of the drawings, the result of the foregoing configuration is such that, when all of the cutter elements 50 to 56 are mounted in their respective apertures in the leading vane surfaces, they are inclined away from the axis of rotation at increasing angular increments from the innermost to the outermost and their cutting edges are stepped downwardly axially of the head in such manner that, if the head is rotated about its axis the cutters will present a cutting profile such as is diagram- 4 matically shown in Fig. 4. As hereinbefore described, the angular increment between each of the respective cutters 50 to 55 are substantially the same, except for the outer most cutters 55 and 56 which have substantially the same maximum angularity of 30 relative to the axis of rotation of the head. Thus, in the preferred embodiment shown, the angular increments between each of the cutters 50 to 55 of the tool illustrated is approximately 5". Proper selection of the overall maximum angle of the outermost cutters and the incremental angularity between each of the cutter elements prevents excessive wear and damage to the cutting edges and faces of the cutter elements. While it may be possible to mount the cutters at angular increments resulting in an overall maximum angularity of 45", I have found that any approach to such maximum progressively increases the wear on the cutter elements.
In addition to the angularity of the respective cutter elements relative to the axis of rotation and their inclination into the direction of rotation, each cutter is also preferably positioned so that the inside corner of its cutting edge leads the cutting operation. Thus, each cutter is preferably rotated about its individual axis in the direction of rotation in an amount of approximately 12 to set its cutting face at an angle to a centerline extending outwardly along the corresponding leading vane surface from the axis of rotation. The inside corner of the cutting edge of each cutter element is the first part to make con-tact with the material to be cut; the remainder of the cutting edge forming a rake angle with the material in a plane normal to the axis of rotation which progressively increases about the axis from the innermost to the outermost cutters 55 and 56 as best shown in Fig. 4 of the drawings. It is noted that the rake angle of each cutting edge is the same as the acute angle formed by the corresponding cutter axis with the head axis and that the progressive increase in this rake angle around the head axis is also in angular increments of 5 so that the maximum rake angle formed by the cutting edges of the outermost cutters 55 and 56 with material normal to the axis is within 30.
The cutting profile of the material cut by an anger head constructed in accordance with the foregoing description is diagrammatically illustrated in the developed profile of Fig. 12 of the drawings, to show that each cutter element individually initiates its own cutting action in the material 57 in the form of a separate annular cut 58 in the bore or hole, with a slight core spacing 59 between each of the annular cuts. The small amount of core material between the cuts is wiped out by the forward progress of the successive cutter faces as the auger head rotates. This cutting profile is distinguished from that which is commonly obtained with existing tools or augers wherein the cutter elements or bits are spaced on the head so that the resulting profile is smooth and bowl-shaped in formation. 1 have found that the bowl-shaped formation does not enable the head to progress in hard material efficiently and, as a result, the cutter elements are burned and rendered unusable necessitating withdrawal of the tool and replacement or sharpening of the cutter elements with consequent loss of drilling time.
The hardness of the material delays the advancing of the cutting tool because the resultant reaction acts against all of the cutter elements collectively in substantially the same degree and direction when the elements are mounted to accomplish a bowl-shaped formation of the cutting profile. Such delay in the advancement of the tool in hard material dresses the cutter elements and destroys the cutting edges. However, by mounting the cutter elements in the tool or auger head in the manner described herein, wherebythere is' a relative progressive displacement between the successively acting cutter elements radially and angularly relative to the axis of rotation thereaction forces of the material being drilled act individually in different degree and direction on each cutter element to enable the advancement to be continued without dressing and destroying the cutting edges.
Thus, the construction of the augerhead and the arrangement of the cutter elements thereon in-accordance with this invention is significant in reducing the overall cutting time in boring or drilling a hole through material which is relatively hard. By initiating the cutting operation with a small central hole and then enlarging it in a series of steps progressing outwardly from the axis of rotation wherein the actual cutting of the material is individually accomplished at all times on the faces of the cutter elements instead of on their sides,. the auger'head attains a self-piloting action and the cutter elements remain cool and continue the normal drilling operation until completed without damage or stoppage.
Referring now to Figs. 9 and 10 of the drawings, there is shown in partial cross section aportion of one of the vanes of the auger head 10 and one of the axially extending frusto-conical apertures 41. Each cutter element S0 to 56 is in the form of anelongated metallic member made of high speed steel as, for example, a high speed cobalt steel which has a toolportion 60 at one end that is rectangular in section with a bevelled extremity 61 forming a cutting edge 62 contiguous with one rectangular face and extending back towards the opposite face at a suitable angle. The other end of the cutter 'ele ment is tapered to form a frusto-conical shank 63 to occupy the complementary socket provided by any of the axial apertures to 46 in the respective vanes.
Each cutter element is also provided with a shoulder 64 at the side faces intermediate the tool and shank portions which is utilized in mounting or setting the cutter element in the vanes for locating the proper faces of the cutter element relative to the corresponding vane leading surface and the direction of rotation of the auger head. It is seen that there is no face to face contact between any part of the tool portion of the cutter and any portion of the corresponding vane of the auger head. As shown, there is preferably a slight clearance between the cutting face of the cutter element and the adjacent shoulder 39 on the corresponding leading vane surface. portions 39 of the leading vane edges flush with the bottom of the front cutting face 65 of the cutter element so that the top of such shoulder portion is aligned with the intermediate shoulder 64 on the cutter element. It is to be noted that the intermediate shoulder 64 on the cutter element preferably does not rest on the vane shoulder portion 39 and is spaced from the flat surface of the corresponding stepped portion so that the cutter element is held in place solely by means of the interfitting frusto-conical tapered connection between the cutter element shank 63 and the corresponding vane aperture. During the drilling operation, the friction between the cutter element and the apertured socket wall is adequate to prevent turning of the cutter element therein under normal drilling conditions.
Each vane of the auger head is further provided with apertures extending through the vane in a plane substantially transverse to the axis of rotation and each transverse aperture preferably intersects a corresponding axial aperture at a point coincident with the shank extremity of the cutter element therein. With this arrangement, it is a relatively simple matter to remove the cutter element for sharpening or replacement by merely inserting a tapered knock out punch into the transverse apertures 70 in the respective vanes until they engage the shank extremity of the cutter element therein and then, by merely tapping the punch, driving the cutter element out of its socket aperture. This arrangement of an axial socket aperture which is intersected by a transverse aperture through the vane at approximately the point where the shank extremity of the cutter element terminates, prevents the accumulation of material in the socket aperture and minimizes the difficulties resulting from the freezing and locking of the cutter element within its socket.
In order to further assist the removal of the individual It is desired in practice to have the shouldered cutter elements with a knock out punch, eachcutter element is further provided with a transverse undercut 66 on the shank to provide a plural contact bearing surface having a relief and to prevent burring of the tapered shank from the impact of the knock out punch. The cutter elements are preferably made from square 'stock and are machined so that the largest diameter of the tapered shank 63 merges with opposite faces of the stock corresponding to the front and rear faces of the finished cutter element. The front face 65 of the cutter elements may be recessed at its extremity to accommodate an insert 6$ of tungsten carbide to provide an extremely hardtooled cutting edge for each cutter element, as shown in Fig. 5.
The improved construction of the-auger head of this invention effectively reduces the operating limitations inherent in prior constructions and enables the head'to penetrate hard materials without loss of efficiency -or breakdown. The auger head of this invention is selfpiloting so that it will initiate the drilling operation in any material regardless of its hardness by virtue of each cutter element initiating and cutting its own annular core in a stepped down pattern. The resultant profile isexemplified by a small central hole which is successively enlarged by a series of uniformly spaced steps by individual cutter elements which each work at all times on the cutting face instead of on their sides, thereby preventing dressing of the cutter material and destruction of the cutting edges. As a result, a given size hole or bore may be drilled into material of any degree of hardness much faster and with less vibration and maintenance than was formerly obtainable with prior art constructions. The construction of the individual cutter elements and the cooperating construction of the receiving apertures in each of the vanes of the auger head with intersecting transverse apertures for receiving a tapered knock out punch facilitate the ready and efiiceint removal of the cutter elements of the auger head for replacement or sharpening and also eliminates the difficulties incurred by preventing the accumulation of the drilled material in the cutter receiving apertures.
I have shown and described what I consider to be the preferred embodiments of my invention along with similar modified forms and suggestions and it will be obvious to those skilled in the art, that other changes and modifications may be made without departing from the scope of my invention as described by the appended claims.
1. An auger head comprising a rotatable body having a plurality of outwardly extending vanes, each vane having a leading surface stepped outwardly from the axis of rotation at increasing radial distances and rearwardly from the leading vane surface at increasing axial distances progressing outwardly around the axis on successive vanes to at least a pair of outermost radially aligned stepped portions on successive vanes, the respective stepped portions each inclined outwardly from the axis of rotation at increasing angular increments progressively around the axis toward said outermost radially aligned stepped portions which have the same angular disposition relative to the axis, each stepped portion carrying a cutter element extending outwardly therefrom, each cutter element being inclined from the axis of rotation at increasing acute angular increments corresponding to the angular disposition of the respective stepped portions and the angle of inclination of said outermost cutter elements being no greater than a maximum acute angle of 30.
2. An auger head comprising a rotatable body having a plurality of outwardly extending vanes, each vane having a leading surface stepped outwardly from the axis of rotation at uniformly increasing radial distances and rearwardly from the leading vane surface at uniformly increasing axial distances, the axial and rearward distances between successive stepped portions on a vane vincreasing on successive vanes toward at least a pair of outermost radially aligned stepped portions on successive varies, the respective stepped portions each inclined outwardly from the axis of rotation at uniformly increasing angular increments progressing from the innermost around the axis toward said outermost radially aligned stepped portions each of which have the same angular disposition relative to the axis, a cutter element extending outwardly from each stepped portion and inclined into the direction of rotation, each cutter element being inclined outwardly from the axis of rotation at angular increments corresponding to the angular disposition of the respective stepped portions, and each cutter element being turned slightly about its individual axis in the direction 'of rotation to set its cutting edge in leading position relative to succeeding cutters in the order of cutting progression.
3. An auger head comprising a rotatable body having a plurality of outwardly extending vanes, each vane having a leading surface stepped outwardly from the axis of rotation at uniformly increasing radial distances and rearwardly from the leading vane surface at uniformly increasing axial distances, the axial and rearward distances between successive stepped portions on a vane increasing on successive vanes toward outermost radially aligned stepped portions on successive vanes, the respective stepped portions each inclined outwardly from the axis of rotation at uniformly increasing angular increments progressing from the innermost around the axis toward said outermost radially aligned stepped portions each of which have the same angular disposition relative to the axis, a cutter element extending outwardly from each stepped portion and inclined approximately 12 into the direction of rotation, each cutter element being inclined from the axis of rotation at angular increments corresponding to the angular disposition of the respective stepped portions and the angle of inclination of said outermost cutter elements being no greater than a maximum acute angle of and each cutter element being turned approximately 12 about its individual axis in the direction of rotation to set its cutting edge in leading position relative to succeeding cutters in the order of cutting progression.
References Cited in the file of this patent UNITED STATES PATENTS