US2191492A - Drilling implement - Google Patents

Description

Patented Feb. 27, 1940 UNITED STATES PATENT OFFICE...

of Massachusetts Application July 23. 1935, SeriaiNo. 3am

Renewed July 15, 1939 15 Claims. (-01. 255-64) My invention relates to drilling implements, and more particularly, though not exclusively, to rock drill bits of the detachable type.

In the drilling of rock it is found that one o the most serious impediments to long continued drilling with any tool is the wear which results in a blunting of the outermost portions of the tool. A further difliculty in drilling rock lies in the fact that with conventional drill bits there is 10, a rapid loss of gauge, and a consequent need, particularly when the gauge is lost very rapidly, of starting a. hole much larger than the desired diameter of the bottomed hole.- It is further I found in connection with detachable bits that 16 resharpening is a substantial problem, and where resharpening can be accomplished wholly by a grinding operation, or a series of grinding operations, and" forging and retempering can be avoided, it is highly advantageous. [Still another 20 dimculty in connection with rock drilling resides in the fact that with certain forms of tool, rifling of the hole is likely to occur.

It is an object of the present invention to provide improved rock drilling implements which 95 will avoid as many of the 'diflicultie's mentioned as possible, while possessing the advantage of easy resharpening. It is another object, of the invention to provide an improved rock drilling implement in which the different edges shall each'be caused to do a maximum amount of work, whereby the force of the blow may be concentrated on as small alinear extent of edge as practicable, with resultant greater penetration. It is still another object of my invention to provide an 35 improved rock drilling apparatus in which rifling may be'prevented. It is yet another object of my invention to provide an improved rock drilling apparatus in which reaming of the hole may be most effectually accomplished. It a-still 40 further object of my invention to provide an improved rock drilling implement which may bev sharpened in an extremely simple manner with the use of a single grinding wheel. Other'objects and advantages of the invention will hereinafter more fully appear.

In the accompanying drawing, in'which three forms of embodiment which my invention may I said view being taken at right angles to the view Fig. 3 is a front end view of the bit shown in Figs. 1 and 2. I

Fig. 4 is a view corresponding to Fig. 2, showing another illustrative embodiment.

Fig. 5 is a front end view of the bit of Fig. 4. 5

Fig. 6 is a view similar to Fig. 1, showing a third illustrative embodiment of the invention.

Fig. 'l is a central section at right angles to the plane of the sectional portion of Fig. 6, through the bit of Fig. 6. 10

Fig. 8 is a front end view of the bit of Figs. 6 and 7.

Referring first to Figs. 1 to 3 of the drawing, it will be observed that a drill bit, generallydesignated I, is provided with an internally threaded socket 2 by meansof which it may be secured during drilling to the forward end of a threaded shank. Obviously, any other form of connection with a shank might be employed without departing from the spirit of the invention. 2 The bit'l is generally cruciform in front end elevation; and comprises a pair of relatively ,narrow, oppositely disposed wings 3 and 4,'and

a pair of relatively wide, oppositely disposed wings 5 and 6 arranged at right angles to the wings 3 and 4. The spaces I between adjacent wings provide clearance for the ready escape of the cuttings produced when the bit is in use. The wings 3 and 4 support a diametrically extending cutting edge 8, which is of less than the full diameter of the bit and which terminates, as at the points 9, short of the ends of the wings 3' and 4; and'inclinedsurfaces III of triangular shape extend'from the extremities of the edge 8 to the periphery ll of the bit at the ends ofothe wings 85 3 and l. The edge 8 is formed at the intersection of relatively inclined'planes l2 and i3 bounding the forward end of the wings 3 and 4. The wings 5 and 8 have their forward surfaces formed by inclined planes I4 and I5 extending from- 40 lines of intersection with the planes l2. and i3 forwardly and outwardly toward the periphery of the bit. These surfaces may extend wholly to the periphery of the bit, or only partially thereto, as at; It, thereby to provide reaming or chopping edges, and there may be formedvery narrow segmentalsurfaces I] at the centralpor-- tions'of theends of the wings 5 and 8. As will be noted in Figs. 1 and 2, the surfaces l1 and the cutting edge 8 may desirably be located inthe same transverse plane perpendieular to the axis of the bit. It is not imperative that this arrangement exist, but excellent results arm-attainable with this relatively equal distribution of the. force of the blow on a uniform plane of'advan'ce} A u.

cleansing fluid delivery passage l9 opens through the forward surface of the bit in the angle between one of the pairs of wings, herein 4 and 5.

It is important to note that although the rearward ends of the inclined surfaces 10 lie back of the foremost transverse plane of the bit, the over-all diametric dimension in the central line of the wings 3 and 4 is equal to, though set back from, the over-all dimension of the bit between the most remote portions of the surfaces H. Accordingly, no rifling of the hole is possible.

The mode of operation of this form of the invention will be readily understood. As the bit is mounted upon the end of a percussively actuated and rotated shank, the edge 6 will cut away the rock in a circle of somewhat smaller diameter than the over-all diameter of the drill bit. The reaming or chopping edges I! will, however, not only concurrently maintain the full diameter of the hole by chopping away and inwardly breaking the stone about the periphery of the hole, but will also break loose the stone between the periphery of the hole and the circular zone cut out by the edge 8. Accordingly, greater penetra tion by the edge 8 will be possible, and the reaming edges not only will be cause to perform their function of maintaining the diameter of the hole, but will also break away the stone in a substantial annulus disposed inwardly of the periphery of the hole. The extremities of the wings 3 and 4 being in the diameter of the bit at the periphery of the hole, will very effectually prevent any tendency to rifle, and will maintain the bit at all times central of the hole being drilled. The formation of the inclined surfaces In will not be found to reduce the effectiveness of the bit materially, because the reaming or chopping edges will remove the stone which the deliberately removed potential extremities of-the cutting edge 8 would have cut away, and indeed the lessened total cutting edge length will be found instead to permit a greater unit cutting effect throughout the length of the cutting edge, and a very efficient drilling.

With reference to the species shown in Figs. 4 and 5, it will be observed that the wings 3 and 4 replace the wings 3 and 4 of the species of Figs. 1 to 3, but that aside from the difference in the formation of the extremities of wings 3 and 4 there is essential similarity between the two bits. The wings 5 and 6, the edges and surfaces IB and ILthe plane surfaces l2, l3, l4 and I5, and the cleansing fluid conducting passage l9, are essentially the same. The surfaces extending from the points at the extremity of the cutting edge 8 are, however, not relatively conical, as in the bit of Figs. 1 to 3, and of an extent reaching from the extremities of the cutting edge completely to the periphery of the bit. Instead there is provided at the end of each wing 3 and 4' a relatively plane triangular surface 2| extending from the end of the edge 3 to a line 22 extending across the outer edge of the wing from the outermost rearmost points in the surfaces [2' and I3; and a chopping or reaming surface 23 of segmental form, and advantageously in a plane extending substantially at right angles to the axis of the bit, is provided at the end of each wing. It will be noted, therefore, thatthe surfaces 23 provide additional small chopping or reaming surfaces to the rear of the edges l8 and surfaces l1; and these serve to maintain clean and smooth the bore of the hole. Because of their position to the rear of the forward end of the bit, they do not carry the brunt ol the cutting or reaming action, and therefore may be of reduced size. They contribute nevertheless to the beneficial working of the bit. In this form of the invention, as in the embodiment of Figs. 1 to 3, the overall dimension of the bit in the central line of the Wings 3 and 4 is equal to the over-all dimension in the direction of the central line of the wings 5 and 5, so that the surfaces I1 and 23 at their outer edges lie substantially equal distances from the axial line of the bit. The surfaces 2| need not necessarily be plane, and the surface 23 need not necessarily lie in a plane extending at right angles to the axis of the bit. The mode of operation of this bit requires little further explanation. As the edge 8 chops away the stone occupying the central portion of the desired line in advance of the hole, the edges l6 and surfaces I'I ream the hole and the rearwardly disposed surfaces 23 keep the hole smoothed up and truly round. Referring now to the bit of Figs. 6, 7 and 8, it

will be noted that this bit comprises wings 3 and 4 of relatively narrowwidth, and wings 5 and 6 of relatively greater width, the wings 3" and 4 being alined and the wings 5 and 6' being alined, the wings 3 and 4 being at right angles to the wings 5 and 6 Clearance is provided at l for the escape of cuttings. The wings 3 and 4 have at their forward end surfaces 2| and 22 extending from the lateral edges of the wings forwardly to intersect in radial cutting edges 3. These cutting edges extend from the outer extremities of the Wings 3'' and 4'' toward the center of the drill bit, but terminate a substantial distance short of. the axis of the bit. The Wings 5' and Ii" have their forward surfaces formed by an arcuate surface 24, formed by the action of a grinding wheel presented to the bit or to which the bit is presented, so that the wheel forms the surface 24 at a single grinding operation. The surface 24 is both arcuate transversely of the bit in the direction of the wings 5 and I, and also arcuate, as indicated at 25 in Fig. 'I, in a direction at right angles to the central line ofthe wings 5 and 6". Thus it may be said that the surface 24 is arcuate with respect to axes disposed relatively at right angles to each other, such axes lying in the central planes of the wings. As a result of the appropriate selection of agrinding wheel so that its diameter and the curvature of its periphery transversely are each proper for the purpose to be accomplished, it is possible td cause the surfaces 24 either to produce smooth reaming edges in the plane of the forward end of the bit or to provide, narrow arcuate surfaces 25, as illustrated, at the ends' of the wings 5" and A central cleansing fluid supply passage 2l is provided through the bit. It will be notedthat the inward extent of the cutting edges 8' is determined by the width of the grinding wheel which forms .the surfaces 24, there being shoulders 28 at the inner ends of the wings 3" and 4 iifline with the side surfaces'of thewings i and i". From this it will be obvious'that desirably the width of the grinding wheel should be the same as the width of the wings 5 and I". It will'be obvious from what has been pointed out that this bit will difler materially from the bits of Iflgs.

-1to3and4and5inthatthecuttingedges 8" are disposed at the outer ends of the wings and spaced at their central portion, whereas the edges I and l" extend continuously through the central portion of their respective bits, but ter-r minate short of the ends of the wings which support In this form of the intuition. how- 5 ing from its spirit or the scope of the appended ever, as in the other bits described, there is a reducedover-all length of cutting edge as compared with standard bits, and a greaterunit cutting effort at each point in the cutting edge. Moreover, the over-all dimension in the central line of the wings 3 and 4 is the same as the over-all dimension of the wings 5 and 6 The mode of operation of this form of the invention will be readily understood, and it will be noted that the edges 8 will cut away the stone along lines extending radially of the desired hole, while the slightly blunted edges on the reamin wings 5 and 6 will provide constant clearance at the periphery of the hole and reduce the burden upon the outermost ends of the edges 8.

The central portion of the hole will be broken away as a result of the shocks and the breaking inward of the stone at the inner ends of the edges 8.

From the foregoing description, it will be obvious that I have provided several highly eflicient, rugged, fast-cutting, readily resharpened drill bits, each possessing individual advantages, and all possessing common advantages of'ease of resharpening, maintenance of full diameter of the drill hole, maximum energy per unit of cuttingedge length, and accordingly fast cutting. All may also be used on solid steels.

While I have in this application specifically described three forms which my invention may assume in practice, it will be understood that these forms are shown for purposes of illustration, and that the invention may be modified and embodied in various other forms without departclaims. I

What I claim as new and desire to secure by Letters Patent is:

1. A drill bit having Wings disposed in alined pairs at right angles to each other, chopping or reaming edges at the outer extremities of the wings of one pair, and radially extending cutting edges supported by the wings of the other pair and terminating short of the outer ends of the latter wings.

2. A drill bit having wings disposed in alined pairs at right angles to each other, chopping or reaming edges at the outer extremities of the wings of one pair, and radially extending cutting edges supported by the wings of the other pair and terminating short of the periphery of the bit, the over-all dimension transversely of the bit of said last mentioned pair of wings being equal to the over-all dimension transversely of the bit I of said other pair of wings.

3. A drill bit having wings disposed in alined pairs at right angles to each other, chopping or reaming edges at the outer extremities of the wings of one pair, and radially extending cutting edges supported by the wings of the other pair and terminating short of the periphery of the bit, the over-all dimension transversely of the bit of said last mentioned pair of wings beingequal to the over-all dimension transversely of the bit of said other pair of wings, and said last mentioned pair of wings having segmental chopping edges at their outermost ends.

4. In a drill bit, a pair of chopping edges, a cutting edge, and another pair of chopping edges disposed to' the rear of said'first mentioned chopping edges. 1 5. In a drill bit, cutting and chopping edges at.. the forward end of the bit, and further chopping means disposed to the rear of the forward end of said bit. I

' a pair of -respective outer sides whose axis coincides with the bit axis and at the1r respective inner sides by'a surface of revolution 6. In a rock drill bit, radially extending cutting means and associated reaming means arranged in different quadrants from said cutting means and formed at the opposite extremities of a surface of revolution curving at its central portion arcuately with respect to axes at right angles to each other and having the axis from which it is generated ahead of the bit.

7. In a rock'drill bit, pairs of wings arranged at right angles to each other, cutting edges at the outer ends of the wings of one pair, and. reaming or chopping edges at the outer extremities of the wings of the other pair, the forward face of said last mentioned wings being concave both longitudinally and laterally.

. and having mutually diametrically opposite portions carrying chopping edges disposed in their entireties to the rear of the forward end of said bit.

bit and spaced apart by the full diameter of said 9. In a rock drill bit, a shank terminating a plurality of radially extending wings of substantially equal radial extent, arranged in pairs,

the wings of each pair diametrically opposite each other and said pairsat right angles to each other, a pair of diametrically oppositely disposed chopping portions formed at the outer extremities of the wings of one of said pairs and extending circumferentially of the bit, and, in a line midway between said portions and ina plane including the axis of said bit and midway between the sides of the wings of the other pair and at opposite sides of the axis of the bit, alined. cutting-edge portions each of a length materially less than the radius of the bit whereby they terminate short of the outer ends of, the wings midway between i the sides of which they are disposed.

10. In a rock drill bit, reaming means including a pair of diametrically oppositely disposed, narrow, arcuate chopping portions lying in a common plane perpendicular to the bit axis and bounded on their respective outer sides by a surface of revolution whose axis coincides with the bit axis and at their respective inner sides by a surface of revolution whose axis is perpendicular to said bit axis and which is of at least as great radial dimension at the axial line of the drill bit as at any point therein.

ii. In a rock drill bit, reaming means including.

diametrically oppositely disposed, arcuate chopping portions lying at the periphery of the forward end of the bit and bounded on their by a surface of revolution whose axis is perpendicular to said bit axis and whose generatrix is curved, and of maximum radial dimension with respect to its axis in the line of the drill bit axis, and of flatter curvature than the curve of said arcuate chopping portions.

12. In a rock drill bit, pairs of wings arranged at right angles to each other, alined cutting edges on the wings of one of said pairs, said edges spaced by the fullwidth of the wings of the other pair, and reaming edges at the outer extremities of the wings of the latter pair formed between the'p'eripheral surface of said wings and a surface of revolution having its axis parallel to said cutting edges and forward of thglatter.

13. In a rock drill bit, pairs of wings arranged at right angles to each other, alinedcutting edges on the wings of one of said pairs, andspaced arcu- 75 ate chopping edges at the opposite extremities of the other pair 0! wings arcuate only in front elevation, the forward face of said bit bounded primarily by two planes forming a dihedral angle whose edge coincides with said cutting edges and a surface of revolution whose axis is paral1l to said edges and forward of the same.

14. A drill bit comprising a shank terminating in a plurality of radially extendingwings of substantially equal radial extent, said wings carrying edges disposed alternately substantially perpendicular to the axis of said bit and struck on arcs being cut back arcuately so that the centraiporarouse tion of said bit is on a level with the bases of said wedge-shaped supporting portions.

15. A rock drill bit having four wings at its forward end arranged in rectangular relation to each other, two of said wings carrying arcuate chopping edges substantially at the periphery of the bit and having their forward surfaces and the portion or the front end of the bit between them 'formed upon a continuous concave and the other wings carrying wedge-shaped supporting portions terminating in radial cutting edges, the depth of such concave such that the wedgeshaped supporting portions may be ground bya wheel within said concave, and said concave conformed to a surface of revolution whereby the same may be ground by radial presentation of the bit to the periphery of a wheel.

PAUL H. NAST.

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