US3856359A

US3856359A - Anti-coring device for use with bit mounting means on mining, earth working and digging machines

Info

Publication number: US3856359A
Application number: US00399468A
Authority: US
Inventors: C Krekeler
Original assignee: Cincinnati Mine Machinery Co
Current assignee: Cincinnati Mine Machinery Co
Priority date: 1971-09-20
Filing date: 1973-09-21
Publication date: 1974-12-24
Anticipated expiration: 1991-12-24

Abstract

An anti-coring device to protect the bit mounting means on a mining machine, digging machine, earth working machine or the like. The anti-coring device comprises a replaceable member detachable affixed at the forward face of the mounting means and configured with respect to the mounting means to be subjected to the wear by cores which would normally be sustained by the mounting means. In certain embodiments, the anti-coring device will be provided with a notch or perforation through which the bit passes, so that support for the anti-coring device can be provided in part at least by the bit.

Description

nited States Patent 11 Krekeler [1 11 3,856,359 [451 Dec. 24, 1974 Related US. Application Data Division of Ser. No. 181,771, Sept. 20, 1971, Pat. No. 3,778,1 12, which is a continuation-in-part of Ser. No. 842,791, June 30, 1969, Pat. No. 3,622,206, which is a continuation-in-part of Ser. No. 753,398, Aug. 19, 1968, abandoned.

Inventor:

[52] US. Cl 299/92, 37/142 A, 299/86 [51] Int. Cl. E2lc 35/18 [58] Field of Search 299/79-93;

[56] References Cited UNITED STATES PATENTS 3,659,654 5/1972 Davies et al. 37/142 R X Primary Examiner-Ernest R. Purser Attorney, Agent, or Firm-Melville, Strasser, Foster Hoffman [57] ABSTRACT An anti-coring device to protect the bit mounting means on a mining machine, digging machine, earth working machine or the like. The anti-coring device comprises a replaceable member detachable affixed at the forward face of the mounting means and configured with respect to the mounting means ,to be subjected to the wear by cores which would normally be sustained by the mounting means. In certain embodiments, the anti-coring device will be provided with a notch or perforation through which the, bit passes, so that support for the anti-coring device can be provided in; part at least by the bit.

16 Claims, 15 Drawing Figures PATENTEB DEC24 I874 sum 1 p 1 ANTl-CORING DEVICE FOR USE WITH B-IT MOUNTING MEANs N MINING, EARTH WORKING AND DIGGING MACHINES -tor and entitled ANTI-CORING DEVICE FOR USE WITH BIT MOUNTING MEANS ON MINING. EARTHWORKING. AND DIGGING MACHINES. The last mentioned Ser.'No. 181,771 is a continuationin-part of the copending application of the same inventor, Ser. No. 842,791, 1971 June 30, 1969, now US.

MEANS FOR MOUNTING THEM which, in turn, is a continuation-in-part of the copending application of the same inventor (now abandoned), Ser. No. 753,398, filed Aug. 19, 1968 and entitled CUTTER BITS AND MEANS FOR MOUNTING THEM.

BACKGROUND OF THE INVENTION 1. Field of the Invention I The present invention relates to a protective device for the mounting means of cutter bits, digger teeth and the like, and more particularly to a readily replaceable means to protect the mounting means from coring;

2. Description of the Prior Art The anti-coring device of the present invention is applicable to a wide variety of mounting means for a wide 4 variety of cutter bits, digger teeth and the like. The

' mining machines. ln some instances, the bit-mounting means assemblies are so construed as to permit free rotation of the bit in its mounting means. In other instances, the bits are intended to be non-rotatively held within their mounting means.

In use, the mounting means are affixed to a driven element of the mining machine. The driven element may take a number of forms such as a cutter chain, a cutter wheel, a cutter arm or a rotating drum.

Irrespective of the nature of the driven element of the mining machine. the cutter bit-mounting means assemblies are generally arranged thereon in a pattern so that the cut produced thereby in the material being mined is of sufficient width to accept a portion of the driven element and thereby permit it to be advanced toward the material being cut. As a consequence, the above mentioned pattern of arrangement of the bit-mounting means assemblies is such that the cutting tips of the bits, as they advance in the cutting direction, follow parallel or concentric paths through the material. While the above mentioned pattern arrangement is intended to bringthese paths as close together as is feasible, they nevertheless are spaced from each other by a short distance. As a consequence, therefwill be formed between adjacent paths a core of unfractured material which will tend to grow as the bits proceed in the cutting direction. Thus, in essence, there will be rows of unfractured material between the paths followed by the bit cutting tips.

The formation of cores in the material being mined is substantially unavoidable. However, core growth is greater in some types of material than in others. For example, material such as relatively clean coal, which iseasily fractured, displays a minimumcore growth. On the other hand, the mining of material such as coal containing stratified impurities (including iron pyrites, sulfur, fire clay, etc. which is difficultly fractured, results in serious core growth.

1 Pat. No. 3,622,206 and entitled, CUTTER BITS AND When cores are formed, a portion of them will lie in the path of travel of the mounting means of the bits. While impact with the mounting means will fracture the cores and remove them, the mounting means themselves are subjected to wear by virtue of this contact or impact. Such wear of the mounting means, caused by the cores, is generally referred to as coring. With the passage of time, this wear will finally result in the necessity for replacing the mounting means.

In the mining means process, bits require frequent replacement and provision is generally made so that their replacement can be easily and quickly affected. Mounting means, on the other hand, generally have a much greater service life than the cutter bits and are not intended for frequent replacement. In general, the mounting means are affixed to the driven element of the mining machine by welding or the like. Thus, replacement of the mounting means is both difficult and time consuming. In addition, mounting means are not made as expandable items, and therefore are far mor expensive than the bits.

While the problem ofcoring has plagued the mining industry for many years, prior art worker have simply accepted it as an unavoidable problem. The present invention is based upon the discovery that if a simple, expendable, inexpensive protective means is removably affixed at the forward face of the mounting means, the protective means will be subjected to the coring or wear normally sustained by the mounting means. When the coring of the protective means of the present invention becomes severe, it may be easily and quickly replaced. Therefore, the service life of the more expensive mounting means is greatly increased.

SUMMARY OF THE INVENTION The anti-coring device of the present invention comprises a metallic member removably mountable at the forward face of a bit mounting means. While the anticoring device may be mounted in any suitable fashion, one simple arrangement entails the provision of means on the mounting means to provide a slot on the forward face thereof. The anti-coring device is provided with a coring device also provides an abutment surface adapted to cooperate with the gauge-determining abutment surface or surfaces on the bit. Thus, in these embodiments the device not only serves as an anti-coring device, but also as a replaceable gauge-determining abutment surface.

In yet another embodiment of the present invention, the anti-coring device is provided with a slot, rather than a perforation, through which the bit extends.

In another embodiment of the present invention the anti-coring device is held in place by the bit and a hook-like engagement of the mounting means. Finally, the anti-coring device may be held in place by the bit alone, there being means to retain the anti-coring device on the bit.

In all of the embodiments of the present invention the anti-coring device does not interfere with replacement of the bits.

As used herein,'the term cutting direction refers to the direction in which the bit-mounting means assembly is moved by the driven element to which they are mounted, irrespective of any movement of the entire machine itself. The term forward surface of the mounting means refers tothat surface substantially facing in the cutting direction and normally subject to cormg.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevational view, partlyin cross section, illustrating an exemplary form of bit-mounting means assembly provided with an anti-coring device of the present invention.

FIG. 2 is a perspective view of the anti-coring device illustrated in FIG. 1.

FIG. 3 is a front elevational view of the structure of FIG. 1.

FIG. 4 is a side elevational view, partly in cross section, illustrating another exemplary form of bit-mounting means assembly and the application of the anti-coring device of the present invention thereto.

FIG. 5 is a side elevational view, partly in cross section, similar to that of FIG. 4, but illustrating the use of an anti-coring device presenting a gauge-determining surface cooperating with the gauge-determining abutment surface ofthe bit. a

FIG. 6 is a side elevational view, partly in cross section, of another form of bit-mounting means assembly with an anti-coring device of the present invention applied thereto.

FIG. 7 is a perspective view of the structure of FIG. 6.

FIG. 8 is a side elevational view, partly in cross section, similar to that of FIG. 6 and illustrating the use of 16 and has a body portion 17 of circular configuration.

FIG. 12 is a side elevational view, partly in cross section, illustrating the application of the anti-coring device of the present invention to the mounting means of a digger tooth.

FIG. 13 is a view, similar to FIG. 12, illustrating an alternate means of affixing the anti-coring device to the mounting means of a digger tooth.

FIGS. 14 and 15 are side elevational views, partly in cross section, and illustrating digger teeth and mounting means therefore, with anti-coring devices supported by the digger teeth.

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 illustrates one exemplary form of bit-mounting means assembly, provided with the anticoring device of the present invention. The bitmounting means assembly is of the type taught in US.

rearward surface 10 and a shank receiving perforation 11 extending therebetween. The diameter of the shank receiving perforation 11 and the diameter of the shank 2 of the bit are so sized that the bit is free to rotate within the shank receiving perforation.

The body portion 8 has a rearward extension 12 terminating in an upstanding anvil portion 13. The anvil portion 13 has an abutment surface 14 thereon adapted to cooperate with the bit shank abutment surface 3 to determine the gauge of the bit (i.e. the depth to which the bit extends in the shank receiving perforation 11). The mounting means has a bottom surface 15 by which it may be welded or otherwise affixed to a driven element of a mining machine.

In use, the. bit-mounting means assembly will be driven in a cutting direction, generally indicated by the arrow A. It will be readily understood that the forward surface 9 of the mounting means body will be subjected to coring, particularly at the peripheral edges thereof.

FIG. 2 is a perspective view of an exemplary form of anti-coring device for use with the mounting means of FIG. 1. The anti-coring device is generally indicated at It will be understood by one skilled in the art that the peripheral configuration of the body portion 17 will be detemtined by the peripheral shape-of the forward surface 9 of the mounting means 7. In the embodiment shown (see also FIG. 3) that portion of the mounting means body 8, through which the shank receiving perforation 11 extends, is generally cylindrical in configuration. Thus, in this particular embodiment, the circular body portion 17 of the anti-coring device will have edge portions substantially conforming to the edge portions of the forward face 9 of the mounting means. This is clearly shown in FIG. 3.

The body portion 17 of the anti-coring device has a central perforation 18 adapted to receive the shank 2 of the bit I with clearance. Thus, the anti-coring device will not interfere with the rotation of the bit.

The anti-coring device has a tongue 19. The tongue may be provided with a transverse corrugation as at 20.

As is most clearly seen in FIGS. 1 and 3, the forward face of 9 of the mounting means 7 may have affixed thereto a U-shaped, strap-like member 21. The member21 forms a slot generally indicated at 22, adapted to receive the tongue 19 of the anti-coring device. As

will be clear form FIG. I, the anti-coring device lies along the forward surface of the mounting means exgagement.

From the above description, it will be apparent that when the anti-coring device 16 is placed in the position shown in FIGS. 1 and 3, it will be held in place by the location of the tongue 19 in the slot 22. Thereafter, the bit 1.may be inserted and a retaining ring 23, or the like, may be affixed thereto at the position of the bit groove'16. In the assembly shown in FIGS. .1 and 3, the bit (extending through the central perforation 18 in the anti-coring device will assure that the tongue 19 cannot be inadvertently dislodged from the slot.22.

The bit I may be removed from the mounting means 7, for purposes of replacement, simply by disengaging the retaining ring 23 therefrom and pulling the bit out of theshank receiving perforation 11. Thus, the anticoring device does not interfere in any way with the replacement of the bit. Whenever the anti-coring device 16 is to be replaced, it is only necessary to remove the bit and disengage the anti-coring device tongue 19 from the slot 22. A new anti-coring device may then be positioned on the mounting means, whereupon the bit may be replaced.

FIG. 4 illustrates another embodiment of cutter bitmounting means of the type taught in US. Pat. No.

3,342,532. In this instance, the bit comprises a hollow conical member 23 which may be provided with a hard cutting tip 24. The bit 23 is adapted to frictionally engage a nose 25 at the forward end of a bit holder, generally indicated at 26. The bit holder 26 has a shank with. a portion 27 of larger diameter and an additional portion 28 of smallerdiameter. The portions 27 and 28'of the bit holder shank are joined by a tapered portion 29, forming a gauge-determining abutment surface on the bit holder. The shank portion 28 may be provided with an annular groove 30 adapted to cooperate with a retaining means.

The mounting means, generally indicated at 31, comprises a body having a forward surface 32, a rearward surface 33 and a bottom surface 34, by which it may be affixed to the driven member of a mining machine. A shank receiving perforation 35 extends inwardlyof the forwardsurface 32.- In the preferred embodiment, the shank'receiving perforation 35 may extend all the way through the rear surface 33, to provide an opening though which fines and foreign material collecting within the shank receiving perforation may exit therefrom. At the point where the shank receiving perforation 35 meets the forward surface 32 of the mounting means, the perforation is outwardly flared or tapered,

V to form a gauge-determining abutment surface 36 on the mounting means. The abutment surface 36 cooperates with the abutment surface 29 on the bit holder 26 to determine the depth to which the bit holder extends into the shank receiving perforation 35.

It will be understood that the shank-portion 28 of the bit holder will have a diameter such that it will be freely rotatable in the shank receiving perforation 35. For purposes of an exemplary showing, the mounting means 31 is illustrated as being provided with a resilient retaining means of the type taught in US. Pat. 2,965,365. In this instance, the mounting means has-a transverse hole 37 partially intersecting the shank receiving perforation 35. The resilient mounting means is located in the transverse hole and comprises a metallic pin 38 surrounded by a body of resilient material 39 except for that portion of the pin which extends into the shank receiving perforation 35. The last mentioned portion of the pin 38 cooperates with the annular notch 30 in the bit holder shank portion 28 to maintain the bit holder in place and to provide a knock-in, pry-out relationship between the bit holder and the mounting means 31.

The forward surface 32 of the mounting means 31 has affixed thereto a U-shaped, strap-like member 40, which may be identical to the member 21 of FIGS. 1 and 3, and which forms a slot 41. The anti-coring device of this embodiment is generally indicated at 42. If that portion of the body of the mounting means 31 containing the shank receiving perforation 35 is rounded, the anti-coring device 42 may be identical to that shown in FIGS. 1 through 3. If the forward face 32 of the mounting means 31 has some other peripheral configuration, it will be understood that the anti-coring device 42 will have a matching peripheral configuration. Again, the anti-coring device has a perforation 43 through which the shank portion 27 of the bit holder extends with clearance. Thus, the anti-coring device 42 will not interfere with the rotation of the bit holder 27, nor will it interfere with the removal and insertion of the bit holder in the shank receiving perforation.

The anti-coring device 42 will be provided with a tongue 44, substantially identical to the tongue 19 and having a transverse corrugation 45, similar to the corrugation 20 in the structure of FIG. 2. Thus, the tongue 44 will be frictionally engaged in the slot 41 when the anti-coring device is in place. Again, since the bit holder 27 extends through the perforation43 in the anti-coring device, it will assure that the tongue 44 will not be inadvertentlydislodged from the slot 41. Re placement of the anti-coring device 42 requires only that the bit-bit holder assembly be removed from the shank receiving perforation 35. Thereafter, the replacement of the anti-coring device may be accomplished in a manner identical to that described with respect to FIGS. 1 through 3.

The'structure of FIG. 5 is similar to that of FIG. 4, and like parts have been given like index numerals. The bit-bit-holder assembly of FIG. 5 is identical to that of FIG. 4. The mounting means is also identical, except that-the shank receiving perforation 35 is not provided with a tapered shoulder or abutment surface 36. In this instance, the perforation 43a, through the anti-coringterfere with either the replacement of the bit-bit holder assembly or its rotation. The anti-coring device 42a may be replaced in the same manner described with respect to the above embodiments.

In all the embodiments thus far described, the bit or bit-bit holder assembly has been of the so-called pick type. There are some embodiments of pick-type bits which are not intended to be rotatable. It will be understood, however that the anti-coring device of the present invention may be applied to the mounting means of non-rotating pick-type bits in the same manner described with respect to the embodiments of FIGS. 1 through 5. If such bits have shanks of noncircular cross section, it will be understood that both the shank receiving perforation in the mounting means and the perforation through the anti-coring device may have an appropriate configuration to receive such shanks. In all instances, the anti-coring device protects the forward face of the mounting means from coring.

FIGS. 6 and 7 illustrate the anti-coring device of the present invention in the form suitable for use with cutter bit-mounting means assemblies of well known type taught, for example, in US. Pat. No. 3,114,537. The mounting means, generally indicated at 46 comprises a metallic block having a shank receiving perforation 47 extending therethrough. The shank receiving perforation 47 is of rectangular cross section. The mounting means may also have a transverse perforation 48 for receipt of a resilent retaining means 49. For purposes of an exemplary showing, the retaining means 49 is illustrated as being identical to the retaining means shown in FIGS. 4 and 5.

The cutter bit, generally indicated at 50, comprises a head portion 51 and a shank portion 52. The shank portion is of rectangular cross section and is adapted to be received in the shank receiving perforation 47. The shank 52 may be provided with a hook-shaped notch 53 adapted to cooperate the metallic rod of the retaining means 49 to hold the cutter bit in seated position.

The head portion 51 of the cutter bit may be provided with a hard cutting tip 51a and gaugedetermining shoulders or abutment surfaces 53 and 54, which cooperate with the top surface of the mounting means 46 to determine the depth to which the shank 52 extends into the shank receiving perforation 47. In the above mentioned patent various forms of abutment surfaces or shoulders are taught. For example, only one of the

shoulders

53 and 54 may be present, or shoulders extending along the sides of the shank (rather than, at the end therof as illustrated) may be provided. The nature of the nature of the various type of shoulders or abutment surfaces on the head portion of the bit does not constitute a limitation on the present invention.

As in the case of the previously described embodiment, the mounting means of FIGS. 6 and 7 may have a slot forming means thereon. For purposes of an exemplary showing a U-shaped strap 55 is illustrated as being affixed to the forward surface 46a of the mounting means. The U-shaped element 55 may be identical to the element 21 of FIGS. 1 and 3, or the element 40 of FIGS; 4 and 5. It may be an integral part of the lug or affixed thereto by welding or the like. The element 55 forms a slot 56 adapted to receive the tongue 57 of an anti-coring means 58. The tongue 57 may be identical to the tongue 19 of FIG. 2 and may have a corrugation 59 identical to that shown at 20 in FIG. 2. This insures a tight frictional engagement between the tongue 57 and the U-shaped element 55.

As has been discussed above, the configuration of the anit-coring device 58 will depend upon the configuration of the mounting means 46. In the embodiment illustrated in FIGS. 6 and 7, the mounting means is essentially block-shaped, having a substantially rectangular forward face 46a. As a consequence, the anti-coring device 58 is illustrated as having a substantially rectangular portion 58a adapted to cover the forward face of the mounting means. While not necessary, the anticoring device 58 may have a second portion 5817 extending rearwardly of the portion 58a and adapted to lie over a portion at least of the top surface 46b of the mounting means. The portion 58b has a longitudinally extending slot 60 located centrally thereof and adapted to accommodate the head portionSl of the cutter bit 50. The slot 60 is so sized as to permit the coaction between the abutment shoulders 53 and 54 of the cutter bit head and the top surface 46b of the mounting means. The portion 58b of the anti-coring device no only provides additional protection for the mounting means, but also serves to maintain the anti-coring device in it proper position. This is accomplished through the coaction of the cutter bit head portion 51 and the slot 60.

FIG. 8 illustrates a cutter bit-mounting means assembly which is substantially similar to that of FIGS. 6 and 7, and like parts have been given like index numerals. Again a U-shaped slot-forming member 55 is provided in association with the lug. The anti-coring device is also substantially similar to that of FIGS. 6 and 7 and again like parts have been given like index numerals.

The embodiment of FIG. 8 differs from that of FIGS. 6 and 7 in that the portion 58b of the anti-coring device is provided with a perforation 61 rather than a slot of the type shown at 60 in FIGS. 6 and 7. In this instance, the shank 52 of the cutter bit extends through the perforation 61 and the gauge-determining

abutment shoulders

53 and 54 coact with the top surface of the portion 58b of the anti-coring device 58. Thus, in this embodiment, the anti-coring device serves not only to prevent coring of the mounting means, but also has an abutment surface for'the shoulders 53 and 54. In this way, wear caused by the abutment shoulders 53 and 54 will be absorbed by the disposable anti-coring device rather than the mounting means itself.

In the embodiment of FIG. 8, it will be understood that dimensional adjustments will have to be made to accommodate the thickness of the anti-coring device. Thus, the location of the transverse perforation 48 in the mounting means will have to be shifted upwardly by a distance equal to the thickness of an anti-coring device, or the shank 52 of the cutter bit will have to be lengthened by the same distance. Again, the bit serves to cooperate with the U-shaped member to lock the anti-coring device in place.

In both the embodiment of FIG. 6 and 7 and the embodiment of FIG. 8, the anti-coring device does not interfere with removal and replacement of the cutter bit 50. In both embodiments, the anti-coring device itself may be readily replaced upon removal of the cutter bit.

FIG. 8 illustrates the application of the principle of the'present invention to bit-mounting means assemblies of the type taught in the above mentioned 'copending application (of which this is a continuation-in-part) in the name of the same inventor, Ser. No. 842,791, filed June 30, 1969, and entitled CUTTER BITS AND MEANS FOR MOUNTING THEM. Briefly, the mounting means (generally indicated at 62) comprises a block-like structure having a shank receiving perforation 63. The axis of the shank receiving perforation 63 is inclined toward the cutting direction (indicated by the arrows B). While the angularity of the shank receiving perforation axis to the cutting direction may be varied, an angularity of less than 90 is generally preferred so that the component of force tending to shove the bit into the shank receiving perforation is greater and so that the resultant cutting stresses on the bit will be more nearly in line with the bit axis.

As illustrated in FIG. 9, the bit (generally indicated at 64) comprises an elongated shank 65, preferably of circular cross section. The upper end of the shank terminates in a clearance surface 66 lying at an angle to the shank axis and is relieved on opposite sides, one such relief being shown at 67. The reliefs form a cutting tip 68 having a cutting surface 69 substantially parallel to the axis of the shank 65. The lower end of the shank terminates in an abutment surface 70 lying at an angle to the shank axis.

The mounting means 62 has a transverse hole 71 extending through the mounting means and intersecting the shank receiving perforation 63. A pin 72 is located in the hole 71. The pin 72 carries an abutment surface 73 adapted to cooperate with the abutment surface 70 on the bit shank, to determine the gauge of the bit.

A retaining means must be provided to prevent loss of the bit during the cutting operation. For purposes of an exemplary showing, the retaining means is illustrated as being a pair of split metal rings 74 and 75 captively held in an annular groove 76 in the mounting means 62. The split metal rings 74. and 75 are so sized as to frictionally engage the bit shank 65.

The mounting means 62 is provided on its forward face 62a with a U-shaped element 77 forming a slot 78. The U-shaped element 77 may constitute an integral part of the mounting means 62 or it may be a separate part affixed thereto by welding or the like. The element 77 may be substantially identical to the element 21 in FIGS. 1 and 3, the element 40 in FIGS. 4 and or the element 55 in FIGS. 6-8.

The anti-coring device is generally indicated at 79. It has a tongue 80 (with a corrugation 81 therein) adapted to be received in the slot 78, in the same manner described with respect to the previous embodiments. The anti-coring device 79 has a portion 79a adapted to cover the forward face or surface 62a of the mounting means. Again the configuration of the portion 790 will depend upon the configuration of the forward surface 62a. For purposes of an exemplary showing, the mounting means 62 is illustrated as having a block-like configuration. Thus, the portion 79a of the anti-coring device may be substantially identical to the portion 58a of the anti-coring device 58 (see FIG. 7).

Preferably, the anti-coring device 79 will have a rearwardly extending portion 79b, similar to the portion 58b of the anti-coring device 58 (see FIG. 7). In this instance. the portion 79b extends along a part at least of the upper surface 62b of the mounting means 62, and has a perforation 82 therein, through which. the bit 64 extends. Thus. the bit cooperates with the tongue 80 to maintain the anti-coring device in place. The anticoring device does not interfere with removal and replacement of the bit 64 and may itself be readily replaced upon removal of the bit 64.

FIG. is similar to FIG. 8 and illustrates asubstantially identical mounting means, cutter bit and retaining means. As a consequence, like parts have been given like index numerals. The embodiment of FIG. 10 illustrates the use of an anti-coring device (generally indicated at 82) which is similar to that shown at 58 in FIG.

8. The anti-coring device 82 has a first portion 82a covering the front surface 46a of the mounting means 46, and a second portion 82b covering a large part of the top surface 46b of the mounting means. The portion 8212 has a perforation 83 therein, adapted to accept the shank 52 of the cutter bit 50. As in the case of the embodiment of FIG. 8, the anti-coring device 82 also serves as a gauge-determining abutment means, cooperating with the abutment surfaces 53 and 54 of the cutter bit.

, Unlike the anti-coring device 58 of FIG. 8, the anticoring device 82 of FIG. 10 is not provided with a tongue to be engaged in a slot-forming means. In this embodiment, the portion 82a of the anti-coring device has a hook-like configuration 82c at its bottom edge which is adapted to engage the bottom surface 46c of the mounting means 46. The portion 82a of the anti coring device will have a width at least as great as that of the forward face 46a of the mounting means. The hook-like element 820 may simply by a continuation of the portion 82a and hence also extend the full width of the surfaces 46a and 46c. Alternatively, the hook-like portion 820 may be of a lesser width, simply constituting a centrally located extension on the portion-82a of the anti-coring device. I

In use, the anti-coring device 82 may be applied to the mounting mean 46 by first engagingthe hook-like portion 820 on the bottom surface 46c of the mounting means. Thereafter, the anti-coring device may be pivoted to the position shown in FIG. 10 and the cutter bit 50 may thereafter be installed. The combination of the hook-like means 82c and the cutter bit 50, passing through the perforation 38, will hold'the anti-coring device in its proper position.

For additional stabilization of the anti-coring device with respect to the mounting means, it is possible to provide the inside surface of the anti-coring device with a lug 84. The lug 84 extends from the inside surfaces of the portions 82a and 82b at the juncture thereof and may be located centrally of the surfaces. Centrally of the mounting means surfaces 46a and 46b, and at the juncture thereof, the mounting means may be provided with a slot 85.

The slot is so positioned and so configured as to .ac-'

cept the lug 84. The interengagement of the lug 84 in the slot 85 will tend to further impede any movement of the anti-coring device transversely of the mounting means.

FIG. 11 illustrates a cutter bit, mounting means and retaining means identical to that shown in FIG. 10 and like parts have been given like index numerals. An anticoring device is generally indicated at 86. It is in most respects similar to the anti-coring device 82 of FIG. 10. Thus, the portion 86a, the portion 86b, the perforation 87 and the hook-like configuration 86c correspond to the portions 82a and 82b, the perforation 83 and the hook-like configuration 82c of FIG. 10, respectively.

The anti-coring device 86 can be installed in the same manner described with respect to the anti-coring device of FIG. 10, and performs the same functions. It

differs from the anti-coring device of FIG. 10 in that transversely of the mounting means 46.

To remove the anti-coring devices of FIGS. and 1 1,, it is only necessary to extract the cutter bit 50. The

anti-coring devices may then be replaced, followed by the replacement of the cutter bit.

FIG. 12 illustrates the application of the anti-coring device of the present invention to the mounting means for a bit 'or digger tooth of a digging or trenching machine. The digger tooth-mounting means assembly of FIG. 12 is illustrated as being affixed to an, element 90. The element 90 may be considered as being the forward portion of the bucket of a rotary or chain-type trenching machine. It will be understood that the element 90 could also be considered as the forward portion of the bucket or shovel of any type of digging machine such as a power shovel, back hoe, or the like. To the forward edge of the shovel element 90 there is affixed a U-shaped element 91 forming a slot 92. It will be understood that the U-shaped element 91 could comprise an integral part of the forward edge of the shovel 90. A mounting means, generally indicated at 93, is affixed to'the bottom surface of the shovel member 90. The mounting means comprises a cylindrical element having a forward surface 94 and a shank receiving perforation 95. The shank receiving perforation 95 has an annular groove 96 therein, in which retaining means 97 and 98 are captively held. For purposes of an exemplary showing, the retaining means '97 and 98 may be split metal rings identical to those illustrated at 74 and 75 in FIG. 9.

The digger tooth, generally indicated at 99, has a cylindrical shank portion 100 adapted to be received in the shank receiving perforation 95 and to be frictionally engaged by the retaining means 97 and 98. While the precise nature of the digger tooth does not constitute limitation on the present invention, it is, for purposes of exemplary showing, illustrated as being of the double-ended type. Thus, at'one end, the-shank 100 terminates in a flat surface 101 lying at an angle to the long axis of the bit and forming a cutting or digging tip 102. The other end of the shank similarly terminates in a flat surface 103 forming a cutting or digging tip 104.

In the position shown, it will, be noted that the surface I03 cooperates with the bottom surface of the shovel member 90 to determine the gauge of the digger tooth. When the cutting tip becomes worn, the digger tooth may be removed and reversed so that the surface 101 will abut the bottom surface of the shovel element 90 and the cutting or digging tip 104 will be exposed.

The anti-coring device is generally indicated at 105. Since the mounting means 93 has been described as being cylindrical, the forward face or surface .94 thereof will be circular. Thus, the anti-coring device 105may be identical to that shown in FIG. 2. Again, it will be understood that the anti-coring device 104 may have a different peripheral shape if the forward face 94 of the mounting means were to have a configuration other than a circular one.

It will be readily understood that the anti-coring device 105 will not interfere with removal and reversal or replacement of the digger tooth 99. When the digger tooth 99 is in place, it will cooperate with the Ushaped element 91 to maintain the anti-coring device in position. The anti-coring device may be replaced in the same manner as described with respect to FIGS. 1 through 3, when the digger tooth 99 has been removed.

FIG. 13 illustrates a modified version of the structure of FIG. 12, and like parts have been given like index numerals followed by a. Again, the element a may comprise the forward portion of the bucket of a trenching machine, a power shovel, a back hoe, or thelike. The primary difference between the embodiment of FIG. 13 and the embodiment of FIG. 12 lies in the fact that the portion 93b of the mounting means 930 has been extended and the Ushaped element 91a is affixed to, or comprised an integral part of, the mounting means 93a. The bit 99a and the retaining means 97a and 98a are essentially identical to their counterparts in the structure of FIG. 12. The anti-coring device a may be in every way identical to that of FIG. 12. The

installation, replacement, operation and characteristics It will be understood that the nature of the retaining means used in the embodiments of FIGS. 12 and 13 does not constitute a limitation on the'present invention. The same is true of the cross sectional configurations of the cutter bit shank and shank receiving perforation, except in so far as the perforation in the anticoring device must be properly configured to receive the bit shank.

FIG. 14 illustrates another application of the teachings of the present invention to a bit-mounting means assembly wherein the bit serves as a digger tooth on the lead edge of a scoop, shovel, or like device of an excavating or earth working machine. In this instance, the

bit 106 has a head portion 107 and a shank portion 108. While the head portion 107 is shown as terminat-- ing in a point, the configuration of the head portion does not constitute a limitation on the present invention and may be determined in part by the type of machine to which it is applied and the nature of the work performed by the machine. The shank 108 is, for purposes of illustration, shown as being cylindrical. Again, its cross sectional configuration does not constitute a limitation on the present invention.

' The bit shank 108 is received in a shank receiving perforation 109 in the mounting means 110. The cross determined by the cross sectional configuration of the bit shank. The exterior configuration of the mounting means 110, again, does not constitute a limitation on the present invention and will be dependent upon the nature of the machine device to which it is affixed. For purposes of an exemplary showing the mounting means 110 is illustrated as being affixed to the lead edge of a shovel 111. The mounting means 110 may be affixed to the shovel in any suitable permanent or removable manner. The mounting means 1 10 has a transverse hole 112 adapted to receive a rodlike element 113. The rodlike element 113 has an abutment surface 114 thereon, adapted to cooperate with an abutment surface 115 on the bit or tooth 106.

The shank receiving perforation 109 is provided with an annular notch 116 containing retaining means 117. The retaining means 117 may again be of any suitable type including one or more split metal rings, or twisted split metal ring, a split metal ring of more than one convolution, etc. The retaining means will have a frictional engagement with the shank 108.

An anti-coring device is shown at 118, in the form of a ferrule element having a shank receiving perforation 119 similar to the perforation 109 and having an annular notch 120. The notch 120 will captively hold retaining means 121 which may be the same as the retaining means 117. The anti-coring device 118 will be inserted on the bit shank and will be shoved into contact with the mounting means 110. It need not be affixed to the mounting means 110 since it can be adequately sup- .ported by-the bit shank.

Forces acting on the tooth 106 will insure that it will remain fully seated despite wear of the parts. In many instances, the digger tooth 106 may be made of rod stock, rather than an expensive forging operation or the like. Similarly, the bit or tooth mounting means may have a simple shank receiving perforation 109 achieved by drilling rather than by broaching or the like.

It will be understood that in the embodiment of FIG. 14, a full line or surface-to-surface contact will be maintained between the bit surface 122 and the shank receiving perforation surface 123 whenever there is a component of cutting or digging force acting on the bit in a direction ranging from a direction which is substantially parallel to the bit axis to a direction which is substantially perpendicular to the bit axis and extending vertically downwardly as viewed in FIG. 14. A typical component of force within this range is indicated by the arrow A.

FIG. illustrates a structure similar to that of FIG. 14 and like parts have been given like index numerals. In this instance, however, the shank 108a of the bit 106:; terminates in an abutment surface 115a which extends rearwardly and upwardly, as opposed to the abutment surface 115 of FIG. 14 which extends rearwardly and downwardly. The mounting means 110 is provided with a transverse perforation 112a similar to the perforation 112 of FIG. 14, but positioned slightly differently, as illustrated. A rod-like element 113a is provided, having an abutment surface 114a. In this instance the abutment surface 1l4a is oriented to lie in abutting relationship to the bit or digger tooth abutment surface 115a.

In all other respects, the structure of FIG. 15 is substantially identical to that of FIG. 14. All of the components act in the same waypln this instance, however, a full line or surface-to-surface contact will be maintained between the bit surface 122a and the shank re-- ceiving perforation surface 123a whenever there is a component of cutting or digging force acting on the bit and lying within the range of directions between a direction substantially parallel to the bit axis and a direction substantially perpendicular to the bit axis and oriented vertically upwardly as seen in FIG. 50. A typical component of force within this range is indicated by the arrow B. I

It will be understood by one skilled in the art that in either of the embodiments illustrated in FIGS. l4 and 15 the transverse hole 112 or 112a could be centrally positioned so that its axis would intersect the axis of the shank receiving perforation. In addition, it would be within the scope of the invention to provide a centrally located transverse perforation and arod-like element having a pair of abutment surfaces. In this way, the cutter bit or digger tooth could be reversed, depending upon the type of work done by the digging or earth working machine.

The bits or digger teeth of FIGS. 14 and 15 may be provided with a shallow depression to receive, the retaining'means 117. Such a depression would increase the retaining ability of the retaining means, but should be shallow so as not to constitute a significant stress raiser. The depression should be so configured as to not present a shoulder interfering with thev pry-out feature of the bits. The depression may lie on one side only of the bit or more than one depression may be provided located at various positions about the bit. Similarly, the depression may be a continuous annular one extending fully about the bit. For purposes of an examplary showing, an annular shallow depression is shown at 124 in dotted lines in FIG. 15. In using the term depression it is to be understood that what is meant is a configuration which will help to increase the holding power of the retaining means with respect to the bit, but not to a degree to preclude the pry-out feature.

The anti-coring device 118 of FIG. 15 is identical to that of FIG. 14 and functions in the same manner. Its exterior configuration will depend upon the configuration of the mounting means 110. The configuration of the perforation 119 will depend upon the cross sectional shape of the bit shank 108a. Again, for purposes of an examplary showing, the anti-coring device 118 is illustrated as a simple cylindrical member having a tapered forward end and a shank receiving perforation of circular cross section.

Modification may be made in the invention without departing from the spirit of it. For example,'in the above described embodiments the anti-coring device may be removably held in place by suitable means. It would be within the scope of the invention to mount the anti-coring device to the forward face of the mounting means by a bolt, a set screw or the like passing through a perforation in the anti-coring device and extending into a threaded hole in the mounting means.

' Clip means, or the like, could also be used.

blies, its use is not intended to be limited to those em-' bodiments shown. The anti-coring device of the present invention may be applied to substantially any type of bit-mounting means assembly, so long as the anticoring device is properly configured to protect those surfaces of the mounting means which are subject to coring.

The embodiments of the invention in which an exclusive property or privelege is claimed are defined as fol- 'lows:

1. An anti-coring device for use with bit and mounting means assemblies mounted on the driven elements of mining machines, digging machines and earthworking machines wherein each of said mounting means has at least one forward surface facing the cutting direction and subject to coring, said mounting means having a perforation therein adapted to receive the shank of a bit, said shank receiving perforation forming an opening in said at least one surface, said shank receiving perforation at said opening being countersunk, said countersink forming a gauge-determining abutment surface adapted to cooperate with a matching gaugedetermining abutment surface on said bit, said anticoring device comprising a disposable element adapted to cover a part at least of said at least one surface of said mounting means, means for detachably maintaining said anti-coring device at said at least one surface of said mounting means, said anti-coring device having a perforation therethrough so positioned therein as to be coaxial with said shank receiving perforation when said anti-coring device is in position on said mounting means, said perforation in said anti-coring device being so sized as to expose said gauge-determining abutment surface on said mounting means.

2. The structure claimed in claim 1 wherein said shank of said bit, said shank receiving perforation and said perforation in said anti-coring device are of circular cross section, said perforations being so sized with respect to said bit shank that said shank is freely rotatable in said perforations.

-3. An anti-coring device for use with bit and mounting means assemblies mounted on the driven elements of mining machines, digging machines and earthworking machines wherein each of said mounting means has at least one forward surface facing the cutting direction and subject to coring, said anti-coring device comprising a disposable element adapted to cover a part at leastv of said at least one surface of said mounting means, means for detachably maintaining said anti-coring device at said at least one surface of said mounting means, said last mentioned means comprising a tongue on said anti-coring device, said mounting means having a slot-forming means on said at least one surface, said tongue being configured to be received in said slot with a frictional fit.

4. An anti-coring device for use with bit and mounting means assemblies mounted on the driven elements of mining machines, digging machines and earthworking machines wherein each of said'mounting means has at least one forward surface facing the cutting direction and subject to coring, said anti coring device compris- -ing a disposableelement adapted to cover a' part at least of said at least one surface of said mounting means and means for detachably maintaining said anti-coring device at said at least one surface of said mounting means, said last mentioned means comprising a tongue on said anti-coring device, said driven element to which said mounting means is affixed having a slot-forming means thereon, said tongue being configured to be received in said slot with a frictional fit.

5. An anti-coring device for use with bit and mounting means assemblies mounted on the driven elements of mining machines, digging machines and earthworking machines wherein each of said mounting means has at least one forward. surface facing the cutting direction and subject to coring, said mounting means being of the type having a substantially rectangular block-likeconfiguration with rearward, top, bottom and side surfaces as well as said at least one forward surface, said mounting means having a perforation therein adapted to receive the shank of a bit, said shank receiving perforation forminganopening in said top surface of said mounting means, said anti-coring device comprisinga disposable element of substantially L-shaped configuration having a first portion adapted to cover said forward surface of said mounting means and a second portion adapted to cover a part at least of said top surface of said mounting means and means for detachably maintaining said anti-coring device on said mounting means with said first portion of said anti-coring device covering said forward surface of said mounting means and said second portion of said anti-coring device covering a part at least of said top surface of said mounting means.

6. The structure claimed inclaim 5 wherein said second portion of said anti-coring device has a notch therein exposing said shank receiving perforation.

7. The structure claimed in claim 6 including a tongue on said first portion of said anti-coring device, a slot forming means on said forward surface of said mounting means, said tongue being configured to be received in said slot with a frictional fit.

8. The structure claimed in claim 5 wherein said second portion of said anti-coring device has a perforation therein adapted to be coaxial with said shank receiving perforation when said anti-coring device is in position on said mounting means, said perforation in said anticoring device having a cross sectional configuration of at least the samedimensions as those of said shank receiving perforation.

9. The structure claimed in claim 8 including a tongue on said first portion of said anti-coring device, a slot-forming means on said forward surface of said mounting means, said tongue being configured to be received in said slot with a frictional fit.

10. The structure claimed in claim 8 wherein said second portion of said anti-coring device adjacent said perforation therein comprises a gauge-determining abutment surface for said bit.

11. The structure claimed in claim 10 wherein said first portion of said anti-coring device is provided with a hook-like configuration adapted to engage said bottom of said mounting means adjacent the juncture of said bottom and said forward surface of said mounting means.

12. The structure claimed in claim 11 including lug means on said anti-coring device, said lug means being configured to engage said mounting means to prevent movement of said anti-coring device transversely of said mounting means.

' 13. An anti-coring device for use with bit and mounting means assemblies mounted on the driven elements of mining machines, digging machines and earthworking machines wherein each of said mounting means has at least one forward surface facing the cutting direction and subject to coring and a perforation therein adapted to receive the shank of a bit, said shank receiving perforation forrning an opening in said at least one surface, said anti-coring device comprising a disposable element adapted to cover a part-at least of said at least one surface of said mounting means, means for detachably maintaining said anti-coring device at said at least one surface of said mounting means, said anti-coring device having a perforation therethrough, said perforation in said anti-coring device being so positioned in said anticoring device as to be coaxial with said shank receiving perforation when said anti-coring device is maintained at said at least one surface of said mounting means, whereby said shank of said bit will extend through said perforation in said anti-coring device and into said shank receiving perforation, said perforation in said anti-coring device being countersunk to form a surface flaring outwardly from said shank receiving perforation, said flaring surface comprising an abutment surface adapted to cooperate with a matching gaugedetermining abutment surface on said bit.

14. The structure claimed in claim 13 wherein said shank of said bit, said shank receiving perforation and said perforation in said anti-coring device are of circular cross section, said perforations being so sized with respect to said bit shank that said shank is freely rotatable in said perforations.

15. An anti-coring device for use with bit and mounting means assemblies mounted on the driven elements of mining machines, digging machines and earthworking machines wherein each of said mounting means has at least one forward surface facing the cutting direction and subject to coring, said mounting means having a perforation therein adapted to receive the shank of a bit, said shank receiving perforation forming an opening in said at least one surface, said anti-coring device comprising a disposable element adapted to lie in abutment with and substantially cover said atleast one sur- 'face of said mounting means and having a peripheral shape substantially the same as that of said at least one surface subject to coring, means for detachably maintaining said anti-coring device in abutment with said at least one surface of said mounting means, said anticoring device having a perforation therethrough, said perforation insaid anti-coring device being so positioned in said anti-coring device as to be coaxial with said shank receiving perforation when said anti-coring device is maintained in abutment with said at least one surface of said mounting means,-whereby said shank of means and said bit shank being of circular cross section and so sized that said bit shank is rotatable within said shank receiving perforation, said perforation in said anti-coring device being of circular cross section and having a diameter at least as great as the diameter of said shank receiving perforation.

16. An anti-coring device for use with bit and mounting means assemblies mounted on the driven elements of mining machines, digging machines and earthworking machines wherein each of said mounting means has at least one forward surface subject to coring, said mounting means having a shank receiving perforation therein to receive the shank of a bit and forming an opening in said at least one surface, said bit being of the type having an elongated shank terminating at its forward end in a cutting tip and terminating at its rearward end in an abutment surface adapted to be in abutment with a gauge determining abutment surface in association with the rearward end of said shank receiving perforation, said anti-coring device comprising a disposable element adapted to lie in abutment with and substantially cover said at least one surface subject to coring and having a peripheral shape substantially the same'as that of said at least one surface subject to coring, said anti-coring device having a perforation therethrough of a diameter at least as great as that of said shank receiving perforation to receive said shank of said bit and means to detachably affix said anti-coring device to said mounting means in abutment with said at least one surface subject to coring with said perforation of said anti-coring device coaxial with said shank receiving perforation.

Claims

1. An anti-coring device for use with bit and mounting means assemblies mounted on the driven elements of mining machines, digging machines and earthworking machines wherein each of said mounting means has at least one forward surface facing the cutting direction and subject to coring, said mounting means having a perforation therein adapted to receive the shank of a bit, said shank receiving perforation forming an opening in said at least one surface, said shank receiving perforation at said opening being countersunk, said countersink forming a gaugedetermining abutment surface adapted to cooperate with a matching gauge-determining abutment surface on said bit, said anti-coring device comprising a disposable element adapted to cover a part at least of said at least one surface of said mounting means, means for detachably maintaining said anti-coring device at said at least one surface of said mounting means, said anti-coring device having a perforation therethrough so positioned therein as to be coaxial with said shank receiving perforation when said anticoring device is in position on said mounting means, said perforation in said anti-coring device being so sized as to expose said gauge-determining abutment surface on said mounting means.

3. An anti-coring device for use with bit and mounting means assemblies mounted on the driven elements of mining machines, digging machines and earthworking machines wherein each of said mounting means has at least one forward surface facing the cutting direction and subject to coring, said anti-coring device comprising a disposable element adapted to cover a part at least of said at least one surface of said mounting means, means for detachably maintaining said anti-coring device at said at least one surface of said mounting means, said last mentioned means comprising a tongue on said anti-coring device, said mounting means having a slot-forming means on said at least one surface, said tongue being configured to be received in said slot with a frictional fit.

4. An anti-coring device for use with bit and mounting means assemblies mounted on the driven elements of mining machines, digging machines and earthworking machines wherein each of said mounting means has at least one forward surface facing the cutting direction and subject to coring, said anti-coring device comprising a disposable element adapted to cover a part at least of said at least one surface of said mounting means and means for detachably maintaining said anti-coring device at said at least one surface of said mounting means, said last mentioned means comprising a tongue on said anti-coring device, said driven element to which said mounting means is affixed having a slot-forming means thereon, said tongue being Configured to be received in said slot with a frictional fit.

5. An anti-coring device for use with bit and mounting means assemblies mounted on the driven elements of mining machines, digging machines and earthworking machines wherein each of said mounting means has at least one forward surface facing the cutting direction and subject to coring, said mounting means being of the type having a substantially rectangular block-like configuration with rearward, top, bottom and side surfaces as well as said at least one forward surface, said mounting means having a perforation therein adapted to receive the shank of a bit, said shank receiving perforation forming an opening in said top surface of said mounting means, said anti-coring device comprising a disposable element of substantially L-shaped configuration having a first portion adapted to cover said forward surface of said mounting means and a second portion adapted to cover a part at least of said top surface of said mounting means and means for detachably maintaining said anti-coring device on said mounting means with said first portion of said anti-coring device covering said forward surface of said mounting means and said second portion of said anti-coring device covering a part at least of said top surface of said mounting means.

6. The structure claimed in claim 5 wherein said second portion of said anti-coring device has a notch therein exposing said shank receiving perforation.

8. The structure claimed in claim 5 wherein said second portion of said anti-coring device has a perforation therein adapted to be coaxial with said shank receiving perforation when said anti-coring device is in position on said mounting means, said perforation in said anti-coring device having a cross sectional configuration of at least the same dimensions as those of said shank receiving perforation.

13. An anti-coring device for use with bit and mounting means assemblies mounted on the driven elements of mining machines, digging machines and earthworking machines wherein each of said mounting means has at least one forward surface facing the cutting direction and subject to coring and a perforation therein adapted to receive the shank of a bit, said shank receiving perforation forming an opening in said at least one surface, said anti-coring device comprising a disposable element adapted to cover a part at least of said at least one surface of said mounting means, means for detachably maintaining said anti-coring device at said at least one surface of said mounting means, said anti-coring device having a perforation therethrough, said perforation in said anti-coring device being so positioned in said anti-coring device as to be coaxial with said shank receiving perforation when said anti-coring device is maintained at said at least oNe surface of said mounting means, whereby said shank of said bit will extend through said perforation in said anti-coring device and into said shank receiving perforation, said perforation in said anti-coring device being countersunk to form a surface flaring outwardly from said shank receiving perforation, said flaring surface comprising an abutment surface adapted to cooperate with a matching gauge-determining abutment surface on said bit.

15. An anti-coring device for use with bit and mounting means assemblies mounted on the driven elements of mining machines, digging machines and earthworking machines wherein each of said mounting means has at least one forward surface facing the cutting direction and subject to coring, said mounting means having a perforation therein adapted to receive the shank of a bit, said shank receiving perforation forming an opening in said at least one surface, said anti-coring device comprising a disposable element adapted to lie in abutment with and substantially cover said at least one surface of said mounting means and having a peripheral shape substantially the same as that of said at least one surface subject to coring, means for detachably maintaining said anti-coring device in abutment with said at least one surface of said mounting means, said anti-coring device having a perforation therethrough, said perforation in said anti-coring device being so positioned in said anti-coring device as to be coaxial with said shank receiving perforation when said anti-coring device is maintained in abutment with said at least one surface of said mounting means, whereby said shank of said bit will extend through said perforation in said anti-coring device and into said shank receiving perforation, said shank receiving perforation in said mounting means and said bit shank being of circular cross section and so sized that said bit shank is rotatable within said shank receiving perforation, said perforation in said anti-coring device being of circular cross section and having a diameter at least as great as the diameter of said shank receiving perforation.

16. An anti-coring device for use with bit and mounting means assemblies mounted on the driven elements of mining machines, digging machines and earthworking machines wherein each of said mounting means has at least one forward surface subject to coring, said mounting means having a shank receiving perforation therein to receive the shank of a bit and forming an opening in said at least one surface, said bit being of the type having an elongated shank terminating at its forward end in a cutting tip and terminating at its rearward end in an abutment surface adapted to be in abutment with a gauge determining abutment surface in association with the rearward end of said shank receiving perforation, said anti-coring device comprising a disposable element adapted to lie in abutment with and substantially cover said at least one surface subject to coring and having a peripheral shape substantially the same as that of said at least one surface subject to coring, said anti-coring device having a perforation therethrough of a diameter at least as great as that of said shank receiving perforation to receive said shank of said bit and means to detachably affix said anti-coring device to said mounting means in abutment with said at least one surface subject to coring with said perforation of said anti-coring device coaxial with said shank receiving perforation.