CN111140178A

CN111140178A - Drill bit holder and combined drill bit holder and base block

Info

Publication number: CN111140178A
Application number: CN201911077828.6A
Authority: CN
Inventors: P·索尔拉米
Original assignee: Sallami
Current assignee: Sallami; Sollami Co
Priority date: 2018-11-06
Filing date: 2019-11-06
Publication date: 2020-05-12
Also published as: JP2020076308A; CA3041373A1; EP3650633A1

Abstract

The present application relates to a drill bit holder and a combined drill bit holder and base block. The bit holder includes a forward portion and a shaft axially depending from the forward portion. The front portion has an axial length that is less than an axial length of the shaft. The combined drill bit holder and base block includes the drill bit holder, the front portion of the drill bit holder having an axial length less than an axial length of the shaft. The base block includes a mounting portion and a device receiving portion including a length that is the same as or less than a length of the mounting portion. The base blocks have a device receiving portion including a length shorter than a length of the mounting portion and adapted to provide increased access to a rear of the drill bit assembly, allowing the base blocks to be mounted closer to one another for micro-milling operations. The shortened drill holder shaft is reconfigured according to the prior art to provide increased retention between the drill holder shaft and the base block bore.

Description

Drill bit holder and combined drill bit holder and base block

Cross Reference to Related Applications

This application claims priority to united states provisional application No. 61/944,676 filed on 26/2/2014, priority to and partial continuation of united states non-provisional application No. 14/628,482 filed on 23/2/2015 (issued on 9,879,531/2018 on 30/1), priority to and partial continuation of united states non-provisional application No. 15/708,292 filed on 19/9/2017, priority to and partial continuation of united states non-provisional application No. 61/983,291 filed on 23/4/2014, priority to and partial continuation of united states non-provisional application No. 14/690,679 filed on 20/4/2015, priority to and partial continuation of united states non-provisional application No. 61/891,683 filed on 16/10/2013, priority to and partial continuation of united states non-provisional application No. 14/512,581 filed on 13/10/2014 (issued on 10,072,051, 11/2018), requires priority from and is a partial continuation of united states non-provisional application No. 12/870,289 filed on 27/2010 (now U.S. patent No. 8,622,482, issued on 7/2014), and requires priority from and is a partial continuation of united states non-provisional application No. 15/928,269 filed on 22/3/2018, the scope of which is allowed by law, and the contents of which are incorporated herein by reference in their entirety.

Technical Field

The present disclosure relates to drill bit assemblies for road milling, mining and trenching machines, and more particularly to drill bit holders and/or drill bit sleeves having shortened leading ends.

Background

The removal of material from land, whether in highway renovation, trenching operations or longwall and other mining operations, has seen many improvements in recent years in the mechanical means to achieve such material removal. To reduce the downtime of such material removal machines, various improvements have been made to drill bit assemblies that define a termination point for the separation of surface material from the pad or ground surface by the machine. This end point at which the material removal apparatus contacts the surface of the material to be removed is conventionally made up of a series of drill bit assemblies which may include a drill bit having a pointed nose, a drill bit holder in which the drill bit is mounted or which may be an integral part, and a drill bit holder block in which the base of the drill bit/drill bit holder is mounted. The bit holder block is mounted on either an endless chain or a chain plate system or a rotatable drum.

Currently, the most common use of such drill bit assemblies is on rotatable barrels, with many such assemblies being mounted on the barrel in a V-shaped or spiral form. This recent improvement is seen in us 6,371,567 and us 6,585,326 where the bit holder or intermediate piece of the bit assembly no longer needs to be held on the bit holder block by a threaded shaft on which a nut holds the bit holder on the bit holder block. This improvement includes a hollow shaft axially slotted on its distal end, and wherein the shaft is drivable into a bore in a bit holder block and the distal end of the shaft is radially compressed between the bit holder shaft and the bit holder block bore with sufficient radial force to maintain a bit holder mounted on the bit block during use.

The elimination of a retaining nut or retaining ring from the distal end of the bit holder shaft makes it easy to remove the bit holder from the bit holder block through the bottom of the bit holder block. Furthermore, the tungsten carbide tip drill bit is removable from the bit holder by punching it outwardly through the bottom of the bit holder block hole.

Another improvement of the drill bit assembly is the introduction of diamond tipped drill bits or combination drill bit/holders. The hardened drill bit tip may be formed of a synthetic PCD material or an industrial powder diamond material embedded in a core or base forming a coating on the tip of the drill bit/holder. With the introduction of such extremely hard materials on the tip of the drill bit cutting assembly, the use of tungsten carbide drill bits mounted on bit holders, which in turn are mounted on bit holder blocks, has in some cases given way to integral combined drill bits/bit holders that have a longer service life than previous tungsten carbide tip three-piece combinations. It should also be noted that, if desired, diamond-tipped bits may also be utilized in conjunction with existing bit holders and bit blocks.

In the case of tungsten carbide tip drill bits, it may be preferred that the drill bit be able to rotate in the bit holder during use to spread the wear characteristics of the drill bit. However, the long service life of the diamond tip surface removal machine means that the distal tip no longer needs to be rotatable.

Another improvement in the material removal process is not only the use of conventional face milling equipment having a helically mounted drill bit assembly conventionally positioned axially center-to-center at 5/8 inches in a helical or V-shaped manner across the barrel; also, a micro-milling apparatus was used in which the bit tip spacing was 0.200 inch centerline-to-center axial spacing between bits. Micro-milling is used not only to remove material achieved by conventional milling, but also to flatten portions of uneven surfaces of roadways, or to remove only upper portions of roadways (perhaps one or two inches) to flatten the roadway, or to allow for delayed resurfacing, thus enabling additional roadway life and cost savings.

Using more bit assemblies on a single barrel, sometimes about 900 such bit assemblies on a 46-54 inch diameter barrel, means that the bit assemblies are mounted on the barrel in a much closer orientation to each other, thus minimizing the space between the bottom end of one bit holder block and the tip end of an adjacent bit holder block. This reduction in the adjacent space between the drill bit blocks means that it is more difficult to access the bottom of the drill bit holder block to drive out the drill bit holder or any combined drill bit/holder from the drill bit holder block than previously known. The structure that increases the proximity distance between the leading end of the drill bit assembly and the trailing portion of the adjacent drill bit assembly provides more space for maintenance personnel to replace the drill bit, holder, or combined drill bit/holder.

Disclosure of Invention

The present disclosure generally relates to drill bit assemblies for road milling, mining and trenching equipment. One implementation of the teachings herein is a drill bit holder, comprising: a body portion including a body axial length; a generally cylindrical hollow shaft depending axially from a bottom of the body portion, the shaft including a shaft axial length that is longer than a body axial length; and an outer surface of the first portion of the shaft adjacent the distal end of the shaft that tapers radially outward as it extends toward the distal end.

Another implementation of the teachings herein is a combined drill bit holder and base block including a drill bit holder, the drill bit holder including: a body portion including a body axial length; a generally cylindrical hollow shaft depending axially from a bottom of the body portion, the shaft including a shaft axial length that is longer than a body axial length; and an outer surface of the first portion of the shaft adjacent the distal end of the shaft tapering radially outward as it extends distally; and the combined drill bit holder and base block includes a base block including: a base mounting portion including a bottom surface; a device receiving portion integrally extending from the base mounting portion opposite the bottom surface; and a seating block bore extending through the device receiving portion, the seating block bore adapted to receive a shaft of a drill bit holder.

These and other aspects of the disclosure are disclosed in the following detailed description of the embodiments, the appended claims, and the accompanying drawings.

Drawings

Various features, advantages and other uses of the apparatus will become more apparent by reference to the following detailed description and drawings in which like reference numerals refer to like parts throughout the various views. It is emphasized that, according to common practice, the various features of the drawings are not to scale. On the contrary, the dimensions of the various features are arbitrarily expanded or reduced for clarity.

Figure 1 is a side elevational view of a first embodiment of a drill bit assembly constructed in accordance with an embodiment of the present disclosure;

figure 2 is a bottom plan view of the drill bit assembly shown in figure 1 constructed in accordance with an embodiment of the present disclosure;

FIG. 3 is a front elevational view of the drill bit assembly shown in FIG. 1 constructed in accordance with an embodiment of the present disclosure;

FIG. 4 is a rear elevation view of the drill bit assembly shown in FIG. 1 constructed in accordance with an embodiment of the present disclosure;

FIG. 5 is an exploded perspective view of the drill bit assembly shown in FIG. 1 constructed in accordance with an embodiment of the present disclosure;

fig. 6 is a rear 3/4 perspective view of the drill bit holder shown in fig. 5 constructed in accordance with an embodiment of the present disclosure;

fig. 7 is a side elevational view of the drill bit holder shown in fig. 5 and 6 constructed in accordance with an embodiment of the present disclosure;

FIG. 8 is an exploded view of a second embodiment of a drill bit assembly of the present disclosure including a diamond tipped combination drill bit/holder constructed in accordance with an embodiment of the present disclosure;

fig. 9 is a rear 3/4 perspective view of the base of the combined drill bit/holder shown in fig. 8 constructed in accordance with an embodiment of the present disclosure;

FIG. 10 is a side elevational view of the base of the combined drill bit/holder shown in FIG. 8 constructed in accordance with an embodiment of the present disclosure;

FIG. 11 is a detailed side elevational view of the enhanced rear access bit holder shown in FIG. 1 constructed in accordance with an embodiment of the present disclosure;

fig. 12 is a side elevational view of the third embodiment of a drill bit holder shown in fig. 7, constructed in accordance with an embodiment of the present disclosure, wherein the distal end of the shaft includes an inverted taper;

fig. 13 is a rear 3/4 perspective view of a third embodiment of the reverse taper drill bit holder shown in fig. 12, constructed in accordance with an embodiment of the present disclosure;

FIG. 14 is a rear 3/4 perspective view of a first modification of a third embodiment of a bit holder constructed in accordance with an embodiment of the present disclosure, the bit holder having an inverted cone similar to that of FIG. 13, but including a tapered annular upper shaft above the inner end of the shaft slot but below the rim portion of the bit holder body;

FIG. 15 is a side perspective view of a fourth embodiment combined drill bit/holder constructed in accordance with an embodiment of the present disclosure including a diamond tip thereon integrally formed with a holder body mounted in the first embodiment of a bit holder block;

FIG. 16 is a bottom 3/4 perspective view of the first embodiment drill bit assembly shown in FIG. 1, constructed in accordance with an embodiment of the present disclosure, which discloses an access space augmentation near the bottom of the first embodiment of the bit holder block;

fig. 17 is an exploded perspective view of a fifth embodiment of a drill bit holder and a second embodiment of a drill bit holder block constructed in accordance with an embodiment of the present disclosure;

FIG. 18 is an exploded side elevational view of a fifth embodiment of a drill bit holder and a second embodiment of a drill bit holder block constructed in accordance with an embodiment of the present disclosure, showing invisible internal elements in phantom;

FIG. 19 is a side elevational view of a fifth embodiment of a drill bit holder constructed in accordance with an embodiment of the present disclosure assembled in a second embodiment of a drill bit holder block, showing invisible internal elements in phantom;

fig. 20 is an exploded perspective view of a sixth embodiment of a drill bit holder and a third embodiment of a drill bit holder block constructed in accordance with an embodiment of the present disclosure;

FIG. 21 is an exploded side elevational view of a sixth embodiment of a drill bit holder and a third embodiment of a drill bit holder block constructed in accordance with an embodiment of the present disclosure, showing invisible internal elements in phantom;

fig. 22 is a side elevational view of a sixth embodiment of a drill bit holder constructed in accordance with an embodiment of the present disclosure assembled in a third embodiment of a drill bit holder block, showing invisible internal elements in phantom;

fig. 23 is an exploded perspective view of a fifth embodiment of a drill bit holder and a third embodiment of a drill bit holder block constructed in accordance with an embodiment of the present disclosure;

FIG. 24 is an exploded side elevational view of a fifth embodiment of a drill bit holder and a third embodiment of a drill bit holder block constructed in accordance with an embodiment of the present disclosure, showing invisible internal elements in phantom;

FIG. 25 is a side elevational view of a fifth embodiment of a drill bit holder constructed in accordance with an embodiment of the present disclosure assembled in a third embodiment of a drill bit holder block, showing invisible internal elements in phantom;

fig. 26 is a front view of a seventh embodiment of a drill bit holder according to an embodiment of the present disclosure, showing invisible internal elements in dashed lines;

fig. 27 is a cross-sectional view of a seventh embodiment of a drill bit holder taken along line a-a of fig. 26, according to an embodiment of the present disclosure;

fig. 28 is a perspective view of a seventh embodiment of a drill bit holder according to an embodiment of the present disclosure;

fig. 29 is a cross-sectional view of a seventh embodiment of a drill bit holder taken along the centerline B-B of fig. 28, in accordance with an embodiment of the present disclosure;

fig. 30 is a perspective view of a first side of an eighth embodiment of a drill bit holder according to an embodiment of the present disclosure;

fig. 31 is a perspective view of a second side of an eighth embodiment of a drill bit holder according to an embodiment of the present disclosure;

fig. 32 is a front view of an eighth embodiment of a drill bit holder according to an embodiment of the present disclosure, showing invisible internal elements in dashed lines;

fig. 33 is a partial cross-sectional view of an eighth embodiment of a drill bit holder taken along the centerline C-C of fig. 31, in accordance with an embodiment of the present disclosure;

fig. 34 is a perspective view of a first side of a ninth embodiment of a drill bit holder according to an embodiment of the present disclosure;

fig. 35 is a perspective view of a second side of a ninth embodiment of a drill bit holder according to an embodiment of the present disclosure;

fig. 36 is a front view of a ninth embodiment of a drill bit holder according to an embodiment of the present disclosure, showing invisible internal elements in dashed lines;

fig. 37 is a partial cross-sectional view of a ninth embodiment of a drill bit holder taken along the centerline D-D of fig. 35, in accordance with an embodiment of the present disclosure;

FIG. 38 is an exploded view of a drill bit assembly according to an embodiment of the present disclosure, showing a front view of a drill bit, a cross-sectional view of a seventh embodiment of a drill bit holder taken along line A-A of FIG. 26, and a cross-sectional view of a fourth embodiment of a drill bit holder block;

FIG. 39 is a front view of a drill bit assembled into a cross-sectional view of a seventh embodiment of a drill bit holder assembled into a cross-sectional view of a fourth embodiment of a drill bit holder block showing the assembled drill bit assembly of FIG. 38, according to an embodiment of the present disclosure;

fig. 40 is a front view of a seventh embodiment of a drill bit holder according to an embodiment of the present disclosure, shown in a configuration in which the seventh embodiment of a drill bit holder is once assembled to a fourth embodiment of a drill bit holder block; and

fig. 41 is a cross-sectional view of the seventh embodiment of a drill bit holder taken along line E-E of fig. 40, shown in a configuration once assembled to the fourth embodiment of a drill bit holder block, in accordance with an embodiment of the present disclosure.

Detailed Description

Referring to fig. 1-4, 8 and 16, a first embodiment of a completed drill bit assembly 20 constructed in accordance with the present disclosure includes a bit holder block 21, bit holders 22 and a drill bit 23. As previously mentioned, a plurality of these assemblies (sometimes up to 900) for micro-milling operations are mounted in a V-shaped or spiral fashion around the outside of a hollow cylindrical barrel (not shown) typically 46-54 inches in diameter. Also, the bottom 24a of the base 24 of the bit holder block 21 of the bit assembly 20 may be mounted on an endless chain or chain and plate system or drum (not shown) for trenching or mining operations.

First embodiment drill bit assembly

Each drill bit assembly 20 includes a first embodiment of a drill bit holder block 21 having a base 24 and a drill bit holder or drill bit/holder mounting portion 25. In this embodiment, the bit holder mounting portion 25 is generally cylindrical and extends partially from the base 24 as previously mentioned. A drill block 21 constructed in accordance with the present disclosure includes an axially shortened annular drill bit holder mounting portion 25 that receives a drill bit holder 22 or drill bit/holder (26a, 26, fig. 8 and 15) in a drill block bore 27 centrally located therein. The shortened axial length of the generally annular bit holder receiving portion 25 is approximately 1.5 inches in length, with a nominal diameter of 1.5 inches (fig. 7). The ratio of the drill holder shaft diameter D, drill holder mounting position and its length L is a generally one-to-one ratio.

As shown most clearly in fig. 11, the shortened shaft may use a modified structure to selectively release or secure the bit holder to the bit holder block 21. The bit holder block bore 27 includes an enlarged (0.030 inch per side) upper shoulder portion 27a having an axial depth of approximately 1/4-3/8 inches. The remainder of the bit bore 27 may be straight cylindrical or non-locking conical, preferably one degree per side. The shortened portion of the bit holder block/bit holder receiving portion is shown most clearly in fig. 1 and 16 and is about 1-1/2 inches in length. The shortened bit holder block bore 27 accepts a shortened bit holder shaft 28 of a bit holder 22 such as shown in fig. 5, 6,7, 12, 13 and 14. The shortened shaft mounting provides a notch 30 that increases access to the base 29 (fig. 9) of the bit holder shaft 28 and also the base of the bit 23 shown in fig. 4 and 16, providing an increased access space 30 of more than one inch to the back of the hollow bit holder receiving portion 25, thus more properly allowing a drive rod or other removal tool (not shown) to drive the bit holder 22 outwardly therefrom from the bottom of the bit holder block bore 27.

The bit holder block 21 mounting base 24 is similar to that previously known, having a generally rectangular bottom 24a that may be slightly curved to fit over the outside of a rotary drum (not shown), with a pair of mounting

holes

24b, 24c therein. The base 24 may widen slightly from its bottom wall 24a and eventually form a pair of

triangular sides

31, 32 along with a peaked front portion that slopes downwardly and outwardly from its upward ridge 39 to deflect material loosened by the tip and body of the drill bit 23 mounted on the drill bit holder 22. At the top of the bit holder block, shown most clearly in fig. 5, is a bit holder block mounting portion 25, which is of generally annular construction, having a bore 27 centrally therethrough, including an upper flared portion 27a, which may be cylindrical in shape or may have a non-locking taper to fit the bit holder 22 therein, such as shown in fig. 14.

As previously mentioned, the remainder or bottom portion of the bit holder block bore 27 may be cylindrical or have an unlocked taper, preferably one degree per side at present, conforming to the distal taper of the bit holder shaft (or not conforming to the distal taper of the bit holder shaft, as will be discussed in more detail below).

Fig. 16 shows how the first embodiment of the drill bit assembly 20 is mounted on a rotary drum (not shown) in an inverted position, where a drive punch (not shown) may be used to drive a drill bit holder 22 out of a drill bit holder block hole, or where a smaller drive pin may be used to drive a drill bit out of a drill bit mounting hole of the drill bit holder.

The recess 30 in which the base 24 of the bit holder block 21 and the bit holder block bore 27 extend as shown in fig. 16 is smoothly shaped to conveniently allow for easier removal therefrom of debris, cement or concrete particles or land (not shown) that may be left behind thereon when gaining access to the base 24 of the bit holder block 21. As shown in fig. 3, the forwardmost portion of the bit holder block 21 may be cut to form a pair of opposed substantially

vertical wall portions

33, 34 which provide increased space for mounting adjacent bit blocks on the drum or endless chain. Thus, a plurality of bit holder blocks 21 may be mounted in proximity to one another, particularly for use in micro-milling operations, with adjacent bit assembly bit tips 23a mounted at 0.200 inch axial spacing, rather than the more conventional 0.625 inch axial spacing seen in conventional bit assemblies mounted on barrels for road milling purposes. The width and length of the bit holder blocks are important in achieving 0.200 inch spacing.

Details of bit holders

First illustrated embodiment of a drill bit holder

In addition to the previously mentioned figures, fig. 5, 6 and 7 disclose detailed views of the drill bit holder 22 of the first embodiment shown in assembly in fig. 1-4 and 16. The bit holder 22 includes a top body portion 35 and a bottom shaft portion 28 (both generally annular). The top or body portion 35 of the bit holder 22 includes a flat upper annular face 36 having a generally cylindrical profile, generally equivalent or very similar to the major diameter of the bit 23; or a bit washer 37 which may be mounted on the upper face 36 and in a central bit bore 38 in the bit holder 22 extending axially through the bit holder body portion 35 and the shaft 28.

The central portion 40 of the bit holder body portion 35 extends outwardly from the generally cylindrical upper bit mounting portion 41 in a convex shape in this embodiment, but it may be convex, conical or concave, but generally shaped to deflect material outwardly therefrom as it is separated by the bit tip 23a and moved axially and outwardly along the bit 23, bit holder 22 and bit holder block 21 bodies.

As the central portion 40 of the first embodiment of the bit holder 22 widens, it terminates at the juncture between the central portion and the foot 42, or "rim portion" of the bit holder 22, which is a cylindrical section approximately 1/2 inches in axial height and nominally 2-5/8 inches in diameter. The rim portion 42 terminates in an annular radially extending flange 43 forming a bottom portion of the main body of the bit holder. This bottom portion is adapted to abuttingly mate with the top annular surface 44 of the bit holder receiving portion 27 of the bit holder block 21 previously described. The abutting fit allows for less critical surfaces to exist between the two portions as the shaft 28 is fully installed in the bit holder block bore 27 than if the tire portion 42 were spatially related to the top surface 44 of the bit holder block 21. Inside the radially extending flange 43 is a U-shaped undercut 45 which meets the shaft 28 of the bit holder 22 at its inner end. This U-shaped groove 45 provides a stress relief between the body portion 35 and the shaft 28 of the bit holder 22, avoiding sharp edges.

The shaft 28 of the bit holder extends axially from the U-shaped groove 45. Immediately adjacent the top portion of the main body shaft 28 is an enlarged portion 46, approximately 1/4-3/8 inches in axial length, which mates with the enlarged top bore portion 27a of the bit holder block bore 27 previously discussed in an interference fit. In this first embodiment, the enlarged portion 46 is generally cylindrical in shape. On a nominal 1-1/4-1-3/4 inch diameter shaft, the interference fit with the bit holder bore is approximately 0.001 to 0.003 inch. Immediately axially outward from the enlarged top section 46 of the shaft 28 is a narrowing 47, approximately 1/8-5/8 inches in length, which may be conical or cylindrical in axial dimension. The distal portion 48 of the shaft 28, which is approximately 1/2 to 1-5/8 inches in length, is a non-locking taper in this first embodiment that extends toward the chamfer 50, along with its radially extending bottom flange 51, defining the bottom of the bit holder shaft 28.

In this first illustrated embodiment of the drill bit holder 22, the central portion 47 and distal portion 48 of the shaft 28 may include a pair of slots, one slot 52 extending to the outer distal end of the shaft, and one internal slot 53, both axially oriented, preferably 180 degrees apart. These slots allow the distal portion 48 of the shaft, nominally 1-1/2 inches in diameter, which may be cylindrical or non-locking conical, to have an interference dimension approximately 0.005-0.030 inches greater than the adjacent bottom portion of the bit holder block bore 27 (as discussed in more detail below), thus allowing the shaft 28 to radially collapse when its interference with the bit holder block bore 27 is greater than that seen in the disclosed solid interference tables. The interference may be referred to as differential interference with respect to the bit holder block bore as it increases moving from the top of the distal portion 48 to its bottom. This interference increases until it creates a radial force of between 5 and 3 thousand pounds of radial force, which maintains the bit holders 22 in the bit holder blocks 21 during rough use experienced by the bit assembly 20.

Experiments and observations have shown that in previous embodiments of the present disclosure utilizing the same bit holder shaft/bit holder block bore taper, most of the interference fit occurred in the upper portion of the slotted taper portion of the shaft. The longer the slotted portion in the shaft, the less bending forces occur at the distal end of the shaft, resulting in less retention force towards the distal end of the shaft.

By reducing the angle of the tapered distal portion 48 near the end of the shaft of the bit holder 22, a greater force is applied radially near the distal end of the shaft to provide a greater differential interference between the shaft 28 and the bit holder bore 27. Sufficient holding force can be obtained with a shorter shaft than hitherto known.

As long as the cylindrical or non-locking conical portion 48 of the drill holder shaft 28 has an increasing convergence towards its bottom flange 51 relative to the drill holder block bore 27, many combinations such as outwardly tapered shaft/cylindrical block bore, cylindrical shaft/inwardly tapered block bore, inwardly tapered bore/less inwardly tapered shaft, inwardly tapered bore/outwardly tapered shaft, etc. may be designed to provide the necessary retaining force between the drill holder and the drill block bore. The non-locking taper typically extends 0.01 to 3.5 degrees per side or up to a total of 7 degrees in diameter.

Referring to fig. 1, 3, 4 and 5, the bit assembly 20 of this first embodiment ultimately has a bit 23 having a body portion with a generally conical brazed carbide distal tip 54 at its upper end, an annular flange at the bottom of the body portion (not shown), and a generally cylindrical shaft 55 which in this first embodiment includes an inwardly extending space for mounting a spring steel C-shaped retainer 56 thereon. In use, this type of drill bit is allowed to rotate in the bit holder bore 38. The bit holder 22 typically does not rotate in the bit holder block bore 27.

Second illustrated embodiment of a drill bit holder

Referring to fig. 8, 9 and 10, a second embodiment of a drill bit assembly 20a of the present disclosure is shown and described. This second embodiment includes a bit holder block base 24 identical to that shown in the first embodiment. However, it also includes an integral drill bit/bit holder 26a having a base 57, the base 57 having a body portion 58 with a shaft 60 extending axially from a lower portion of the body portion. This body portion 58 and axle 60 are substantially identical to the body portion 35 and axle 28 of the first embodiment of the present disclosure. However, the uppermost of the central portion of the body 58 includes an annular recess 61 from which a tapered annular distal portion 62 extends axially. The combination of the outer surface of the distal conical portion 62 and the annular recess 61 provides a bottom surface for mounting an annular tungsten carbide ring 63 that is in the shape of a hollow truncated cone that tapers from its bottom to its top and fits closely over the distal annular portion 62 of the body 58. The upper distal ring portion 62 of the body 58 includes a central recess 62a into which an inverted cone member 64 is received. This reverse taper member 64 is slidingly engaged and retained in the upper portion 62a of the distal recess 62a of the body or base 58. A diamond coated generally conical distal drill tip 66 is mounted in a recess formed in the top of the reverse taper member 64. All of these components are brazed in their respective recesses to form a generally unitary drill/holder 26a that fits in the drill holder block bore 27, similar to the first embodiment of the drill bit assembly 20 of the present disclosure.

The diamond tip 66 at the top of the drill/holder 26a has a significantly longer life than a tungsten carbide tip. As such, this unitary component does not have to rotate due to the long service life provided by the diamond coated tip 66. The shortened shaft 60 of the base 58 of the drill/holder 26a fits in the drill holder block bore 27, similar to the shaft of the holder in the first embodiment, and is easily removable therefrom similar to the first embodiment.

The structure of the top portion of the drill bit/holder is generally found in applicant's U.S. patent No. 6,739,327, where such top portion forms the top portion of the drill bit that is removable from its respective drill bit holder.

Third illustrated embodiment of a drill bit holder

Referring to fig. 12, 13 and 14, a third embodiment of a drill bit holder 70 is shown. This third embodiment of the bit holder 70 also includes an upper body portion 71 and a lower shaft 72 portion. A first modification of the drill bit holder 73 of the third embodiment is shown in fig. 14, discussed in more detail below. In each figure, the upper body portion 71 of the drill bit holder is substantially identical to the upper body portion of the first embodiment drill bit holder 22 shown in figures 1, 3, 5, 6 and 7. Also, the upper portion 74 and the central portion 75 of the shaft 72 of this embodiment are identical to those shown in the first embodiment of the drill bit holder 22 of fig. 5, 6 and 7 in particular. However, the difference between the first embodiment of the drill bit retainer 22 and this third embodiment of the drill bit retainer 70 is seen in the particular non-locking reverse taper of the distal portion 76 of the shaft 72 (as shown in fig. 12-14). This non-locking size reverse taper fits in a cylinder, or preferably a one-degree conventional taper per side of the bit holder block bore 27 as shown most clearly in fig. 11. The reverse taper provides a substantial differential interference fit between the portion of the distal cone 76 and the bit holder block bore 27 over only a portion of the length of the shaft 72 and bore 27.

The applicant has found that in prior art quick-change type bit holder/bit holder block combinations having identical cylindrical or conical distal and bottom portions, respectively, a smaller radial force is exerted in the bit holder shaft as the distal end of the shaft is approached, and a larger radial force is exerted in the bit holder shaft as the upper terminal end of the open slot is approached. Thus, slight differences or inversions of the distal portion of the drill holder shaft diameter tend to equalize the radial forces between the bottoms of the drill holder block bores and along the entire length of the distal portion of the shaft. The applicant proposes this differential interference to distinguish it from the known prior art.

This slight difference in taper (differential interference) may exist along the extent of the shape. In the present disclosure, the axial length of the bottom portion of the shaft having a constant taper is about 1/2 to 1-5/8 inches. In prior art bit holder/bit holder block hole combinations, each portion is subjected to an equal non-locking taper, preferably 1 degree or less per side. In this third embodiment, the drill holder shaft 72 may preferably have a 1 degree outward taper towards the drill holder bore 27, said drill holder bore 27 having a 1 degree inward taper or cylindrical configuration, respectively. Similarly, the bit retainer shaft 72 may be cylindrical with a non-locking taper on the bit retainer block bore 27. The relative convergence of the conical/cylindrical surfaces (differential interference) may be different as discussed in the first embodiment.

Of course, if it is desired to apply a greater force toward the bottom of the distal portion 76 of the shaft 72, a greater degree of non-locking taper difference is desired. The degree of difference in taper is limited only by the limits of the non-locking taper and the diameter of the shaft end and the diameter of the top opening of the bit holder block bore. It is desirable to be able to centre the drill holder shaft in the drill holder block bore 27 to drive it into position.

The non-locking taper is about 3-1/2 degrees per side, or 7 degrees total. The presently illustrated embodiment provides the shortest shaft distal portion. As the differential taper increases toward the limits of the unlocked taper, the length of the shaft and the distal or bottom portion of the bit holder block bore must increase to allow the desired overall retention force to be obtained.

This limited difference (differential interference) of the substantial annular contact surface between the distal end of the shaft and the bottom of the bit holder block bore enables easier access and removal of the bit holder from the bit holder block, requiring only a short movement of the bit holder in the bit holder block for release. The non-locking (currently preferred 1/2 degrees per side) or larger inverted non-locking taper in the nominal 1-1/2 inch diameter of the shaft 72 is sized to fit the bottom portion of the bit holder block bore 27 with some interference that applies approximately 5 to 3 thousand pounds of radial force, but over a shorter axial contact surface distance. One or two slots may be used. A single slot exerts a greater radial force than two slots. The combination of the slotted inverted cone shaft 72 and the generally cylindrical upper extended cylindrical shaft portion 74 having a standard 0.001-0.003 interference with respect to the upper extended portion 27a of the bit holder bore 27 enables this embodiment of the bit holder 70 to be substantially installed in the bit holder bore 27 during use.

Fig. 14 shows a first modification of the bit holder 73 of the third embodiment, in which the upper portion 77 of the bit holder shaft 72 is tapered in shape rather than cylindrical, with a locking or non-locking taper that will fit in a complementary shaped taper in the upper portion of the bit holder block bore (not shown).

Fourth of drill/holderIllustrative embodiments

Fig. 15 discloses a fourth embodiment of a drill/holder 26 of the present disclosure which provides a combined drill/holder which fits into the improved drill holder block 21 shown in the previous embodiments. The drill/holder 26 includes a generally conical distal tip 80 that is coated with diamond or contains a solid diamond tip such that the drill/holder is a unitary structure that fits into the drill holder block bore 27, similar to the previous embodiments described herein. The upper portion or bolster 81 of the drill/holder behind the tip comprises a generally convex member of tungsten carbide having a notch 82 at the top thereof into which a diamond tip 80 is positioned and brazed. Likewise, the enlarged base 83 of the bolster 81 is brazed onto the top of the main body portion 86 of the drill/holder 26.

This body portion 86 includes a concave countersunk or slightly concave top surface 85 to which the bolster is brazed, and is an outwardly and axially extending body portion 86, which in this embodiment may be concave or convex in surface profile. The lower portion 86 of this centrally concave portion terminates in a generally cylindrical rim or base portion 87, which generally cylindrical rim or base portion 87 is similar to the base portion shown in the previous embodiments, except that its distal end includes a 45 degree inwardly extending portion 88 that terminates in a flat annular face. This 45 degree taper 88 provides access to a generally forked tool (not shown) which may be used as an alternative to the floating pin previously mentioned to extract the drill bit/holder from its drill bit holder block bore. Also in this embodiment, the fourth embodiment drill/holder 26 may be inverted similar to the first embodiment shown in fig. 16. Thus, where the improvement of the recessed and shortened rear of the bit holder block allows for increased access to the bit/holder shaft (not shown), the extraction punch may be more easily used which will force the bit/holder shaft axially outward from the bit holder block bore 27. Again in this fourth embodiment, the diamond tip provides greatly improved bit/holder life so that the bit/holder 26 does not have to rotate, but can be securely mounted in the bit holder block hole 27 with a radial force of 5 to 3 thousand pounds, similar to the previously shown embodiments.

Fifth illustrated embodiment of a drill bit holder

Referring to fig. 17-19, a fifth embodiment of a bit holder 100 and a second embodiment of a bit holder block or chassis block 102 are shown. In this illustrated embodiment, the bit holder 100 is a substantially standard length shaft bit holder of approximately 2-3/4 inches, which includes a nose or bit holder body 104 and a substantially cylindrical hollow shaft 106 depending axially from the bottom of the nose 104. This design can also be successfully implemented with shafts of various lengths. In this exemplary implementation of the fifth illustrated embodiment, the nose 104 is generally annular in shape and includes a frustoconical first portion 108 extending axially from a top surface 110 (e.g., a flat annular top surface), a frustoconical second portion 112 extending axially from the first portion 108, and a generally cylindrical tire portion 114 extending axially from the second portion 112. A chamfer 116 extends from the bottom of the tire portion 114 to a rear flange 118, which may be generally annular. The back flange 118 includes a pair of horizontal slots 120 (one shown in fig. 17-19) generally perpendicular to the longitudinal axis of the bit holder 100, one on either side of the back flange 118. The horizontal slots 120 are adapted to receive a pair of bifurcated tines insertable between the seat of the nose 104 of the drill bit holder 100 and the second embodiment of the seat block 102 or the third embodiment of the seat block 202 (fig. 23-25), the shaft 106 of the drill bit holder 100 being inserted into the second embodiment of the seat block 102 or the third embodiment of the seat block 202 and retained therein by an outward radial force in use. Other base block configurations may be used without departing from the concept of this design.

The shaft 106 includes an elongate first slot 122 extending axially upwardly or forwardly from a distal end 124 (e.g., a generally annular distal end) of the shaft 106 to an upper terminal end 126 near an upper or forward end of the shaft 106. In this exemplary implementation, the shaft 106 also includes an internally oriented second slot 128 (fig. 17) positioned approximately 180 degrees around the annular shaft 106 relative to the first slot 122. This second slot 128 is parallel to the first slot 122 in the illustrated embodiment and is an internal slot having a rearward terminal end 130 (fig. 17-19) that is inwardly adjacent the distal end 124 of the shaft 106 and a forward terminal end 132 (fig. 18 and 19) that is longitudinally and axially generally coincident with the upper terminal end 126 of the first slot 122.

In the embodiment shown here, the shaft 106 also includes a lower or first outwardly tapered portion 134 that extends axially from a stepped shoulder 136 near the distal end 124 of the shaft 106. The stepped shoulder 136 increases or rises as it extends axially from the distal end portion 138 of the shaft 106 near the distal end 124 of the shaft 106 down toward the outer tapered portion 134. The lower outwardly tapered portion 134 extends upwardly or axially from a stepped shoulder 136 of the shaft 106 and terminates longitudinally in a generally central groove 122. The shaft 106 also includes an annular shoulder 140 separating the lower outwardly tapered portion 134 from an upper or second tapered portion 142, the upper or second tapered portion 142 extending from the shoulder 140 to a forward

terminal end

126, 132 generally adjacent the top of the shaft 106 or the

grooves

122, 128, respectively. An annular shoulder 140 is disposed between the first outwardly tapered portion 134 and the second tapered portion 142. The annular shoulder 140 decreases or decreases in diameter as it extends axially from the first outwardly tapering portion 134 to the second tapering portion 142. A generally cylindrical top portion 144 of the shaft 106 extends from a location near the second tapered portion 142 toward the rear flange 118 representing the base or bottom of the nose 104 of the bit holder 100. The top of the shaft 106 may include a rounded joint 146 (fig. 18 and 19) between the top portion 144 of the shaft 106 and the rear flange 118 of the nose 104 of the drill bit holder 100, in order to avoid sharp corners that may provide areas where stress cracks initiate. In other embodiments, shaft 106 may comprise a different configuration, for example, lower portion 134 and/or upper portion 142 of shaft 106 may comprise a generally cylindrical shape, an outward taper, an inward taper, a slight stretching angle, or a slight pulling angle.

The central bore 148 extends axially from the top surface 110 of the drill bit holder 100 to the distal end 138 of the shaft 106. The central bore 148 is adapted to receive the shaft of a drill bit (not shown). The central bore 148 and the

slots

122, 128 allow the generally C-shaped annular sidewall of the shaft 106 to radially contract when the shaft is installed in the bore 150 (fig. 17 and 18) of the base block 102 or the bore 250 (fig. 23 and 24) of the base block 202. (the slot 122 may be used alone in some applications.

The second embodiment of the base block 102 includes a base mounting portion 152, the base mounting portion 152 including a base 154, the base 154 being mountable on the outside of a drum (not shown), or to a drum-mounted stand or riser, which is part of a road milling apparatus or similar drum design machine. The front or leading portion of the base mounting portion 152 may include a pair of rearwardly

angled shoulders

156 and 156. A generally annular and/or cylindrical bit holder receiving portion 158 that holds the base block 102 adjacent to a base mounting portion 152 on a cartridge or a mount or riser on a cartridge includes a central bore 150, the central bore 150 extending axially from a front face 160 of the receiving portion 158 to a rear distal portion 162 of the base block 102. The bore 150 includes a counter bore 164 adjacent the front face 160 and an outwardly tapered portion 166 adjacent the rear distal portion 162. The bore 150 of the base block 102 is adapted to receive the shaft 106 of the bit holder 100, as shown in fig. 19, and the bore 148 of the bit holder 100 is adapted to receive the shaft of a drill bit (not shown). Alternatively, the bore 250 of the base block 202 is adapted to receive the shaft 106 of the bit holder 100, as shown in fig. 25.

Sixth illustrated embodiment of a drill bit holder

Referring to fig. 20-22, a sixth embodiment of a drill bit holder 200 and a third embodiment of a drill bit holder block or base block 202 are shown. The bit holder 200 includes a nose or bit holder body 204, and a generally cylindrical hollow shaft 206 that depends axially from the bottom of the nose 204. The shaft 206 of the drill bit holder 200 of the sixth embodiment is shorter than the approximately 2-3/4 inch generally standard length shaft of a standard drill bit holder, in this exemplary embodiment the length of the shaft 206 of the drill bit holder 200 is approximately nominally 1-3/4 inches. This design can also be successfully implemented with shafts of various lengths. In this exemplary implementation of the sixth illustrated embodiment, the nose 204 is generally annular in shape and includes a frustoconical first portion 208 extending axially from a top surface 210 (e.g., a flat annular top surface), a frustoconical second portion 212 extending axially from the first portion 208, and a generally cylindrical tire portion 214 extending axially from the second portion 212. A chamfered surface 216 extends from the bottom of the tire portion 214 to a rear flange 218, which may be generally annular. The back flange 218 includes a pair of horizontal slots 220 (one shown in fig. 20-22) generally perpendicular to the longitudinal axis of the drill bit holder 200, one on either side of the back flange 218. The

horizontal slots

220 and 220 are adapted to receive a pair of bifurcated tines insertable between the base of the nose 204 of the bit holder 200 and the third embodiment of the base block 202 into which the shaft 206 of the bit holder 200 is inserted and retained by an outward radial force in use to the third embodiment of the base block 202. Other base block configurations may be used without departing from the concept of this design.

The shaft 206 includes an elongate first slot 222 extending axially upward or forward from a distal end 224 (e.g., a generally annular distal end) of the shaft 206 to an upper terminal end 226 near an upper or forward end of the shaft 206. In another embodiment, the shaft 206 may also include an internally oriented second groove (not shown) positioned approximately 180 degrees around the annular shaft 206 relative to the first groove 222. This second slot may be parallel to the first slot 222 and may be an internal slot having a rearward terminal end (not shown) facing inwardly adjacent the distal end 224 of the shaft 206 and a forward terminal end (not shown) longitudinally and axially generally coincident with the upper terminal end 226 of the first slot 222.

In the embodiment shown here, the shaft 206 also includes a lower or first tapered portion 228 that extends axially from a stepped shoulder 230 near the distal end 224 of the shaft 206. The stepped shoulder 230 increases or rises as it extends axially from the distal end portion 232 of the shaft 206 near the distal end 224 of the shaft 206 to the lower tapered portion 228. The lower tapered portion 228 extends upwardly or axially from a stepped shoulder 230 of the shaft 206 and terminates longitudinally in the generally central groove 222. The shaft 206 also includes an annular shoulder 234 separating the lower tapered portion 228 from an upper or second tapered portion 236, the upper or second tapered portion 236 extending from the shoulder 234 to generally adjacent the top of the shaft 206. The annular shoulder 234 is disposed between the first tapered portion 228 and the second tapered portion 236. The diameter of the annular shoulder 234 decreases or decreases as it extends axially from the first tapered portion 228 to the second tapered portion 236. The generally cylindrical top portion 238 of the shaft 106 extends from a location near the second tapered portion 236 toward the back flange 218 representing the base or bottom of the nose 204 of the bit holder 200. The top of the shaft 206 may include a rounded junction 240 (fig. 21 and 22) between the top portion 238 of the shaft 206 and the back flange 218 of the nose 204 of the drill bit holder 200 to avoid sharp corners that may provide areas where stress cracks initiate. In other embodiments, the shaft 206 may comprise a different configuration, for example, the lower portion 228 and/or the upper portion 236 of the shaft 206 may comprise a generally cylindrical shape, an outward taper, a slight draft angle, or a slight draft angle.

The central bore 242 extends axially from the top 210 of the drill bit holder 200 to the distal end 224 of the shaft 206. The central bore 242 is adapted to receive the shaft of a drill bit (not shown). The central bore 242 and the slot 222 allow the generally C-shaped annular sidewall of the shaft 206 to radially contract when the shaft is installed in the bore 250 (fig. 20 and 21) of the base block 202.

The base block 202 includes a base or mounting portion 244 and a shortened front end or bit holder receiving portion 246 opposite a base 248 of the base block 202. The shortened front end or receiving portion 246 may have an annular or generally cylindrical shape, or in a first modification of the third embodiment of the base block 202, the shortened front end or receiving portion 246 may include relatively flat sides (not shown). The base 248 may be flat or slightly recessed to fit a canister or additional mounting plate, stand-offs, or risers on which a plurality of base blocks may be mounted. In this exemplary embodiment, the length of the shortened receiving portion 246 is approximately 1-1/2 inches or more from the front face 252 of the base block 202, which also corresponds to the front face of the shortened receiving portion 246, to the back face 254 of the shortened receiving portion 246, which provides increased access space of approximately 7/8 inches from the back face 254 of the shortened receiving portion 246 to the back 256 of the base block 202. The receiving portion 246 includes a base block aperture 250 that is symmetrical with the shaft 206 along a centerline, and in this exemplary implementation has a central nominal 1-1/2 inch diameter. In this exemplary implementation, the bore 250 is tapered and includes a counter bore 258 adjacent the front face 252 of the base block 202. In other embodiments, the bore 250 may be cylindrical, generally cylindrical, inwardly tapered, outwardly tapered, or any combination thereof.

The back face 254 of the shortened receiving portion 246 in this embodiment includes a semi-cylindrical corner groove 260 at the radially outermost portion of the base block bore 250. The angular slot 260 allows increased space for a floating pin or tool (not shown) to operate to drive a drill bit (not shown). The portion 262 of the base block 202 includes an extension of the arcuate section 264 of the bore 250 that extends from the back face 254 of the shortened receiving portion 246 to a location near the rear 256 of the base block 202. In this exemplary embodiment, the arcuate section 264 of the tapered bore 250 has a reduced radius relative to the radius of the bore 250. The bore 250 of the base block 202 is adapted to receive the shaft 206 of the drill bit holder 200, and the bore 242 of the drill bit holder 200 is adapted to receive the shaft of a drill bit (not shown). Alternatively, the bore 250 of the base block 202 is adapted to receive the shaft 106 of the fifth embodiment of the bit holder 100, as shown in fig. 23-25.

Seventh illustrated embodiment of a drill bit holder

Referring to fig. 26-29, a seventh embodiment of a drill bit holder 300 is shown. The bit holder 300 includes a nose or bit holder body 302, and a generally cylindrical hollow shaft 304 that depends axially from the bottom of the nose 302. The shaft 304 of the drill bit holder 300 of the seventh embodiment is shorter than the approximately 2-3/4 inch generally standard length shaft of a standard drill bit holder, in this exemplary embodiment the length of the shaft 304 of the drill bit holder 300 is approximately nominally 1-3/4 inches. This design can also be successfully implemented with shafts of various lengths. In this exemplary implementation of the seventh illustrated embodiment, the nose 302 is generally annular in shape and includes a frustoconical portion 306 extending axially from a top surface 308 (e.g., a flat annular top surface), and a generally cylindrical tire portion 310 extending axially from the frustoconical portion 306. A chamfered surface 312 extends from the bottom of the tire portion 310 to a rear flange 314, which may be generally annular.

The shaft 304 includes an elongate first slot 316 extending axially upward or forward from a distal end 318 (e.g., a generally annular distal end) of the shaft 304 to an upper terminal end 320 near an upper or forward end of the shaft 304. In another embodiment, the shaft 304 may also include an internally oriented second groove (not shown) positioned approximately 180 degrees around the annular shaft 304 relative to the first groove 316. This second slot may be parallel to the first slot 316 and may be an internal slot having a rearward terminal end (not shown) facing inwardly adjacent the distal end 318 of the shaft 304 and a forward terminal end (not shown) longitudinally and axially generally coincident with the upper terminal end 320 of the first slot 316.

In this illustrated embodiment, the shaft 304 also includes a lower or first outwardly tapered portion 322, shown at interior angle a in fig. 26, adjacent to the distal end 318 of the shaft 304. A lower outwardly tapered portion 322 extends upwardly or axially from near the distal end 318 of the shaft 304 and terminates longitudinally in a generally central groove 316. The shaft 304 also includes an annular shoulder 324 separating the lower outwardly tapered portion 322 from an upper or second portion 326, the upper or second portion 326 extending from the shoulder 324 to generally adjacent the top of the shaft 304. An annular shoulder 324 is disposed between the first outwardly tapered portion 322 and the second portion 326. The diameter of the annular shoulder 324 decreases or decreases as it extends axially from the first outwardly tapered portion 322 to the second portion 326. The second portion 326 of the shaft 304 extends from a location near the annular shoulder 324 toward the back flange 314 representing the base or bottom of the nose 302 of the bit holder 300. The top of the shaft 304 may include a rounded junction 328 between the second portion 326 of the shaft 304 and the back flange 314 of the nose 302 of the drill bit holder 300 to avoid sharp corners that may provide an area where stress cracks initiate. In other embodiments, the shaft 304 may comprise a different configuration, for example, the lower portion 322 and/or the upper portion 326 of the shaft 304 may comprise a generally cylindrical shape, an outward taper, an inward taper, a slight stretching angle, or a slight pulling angle.

A central bore 330 extends axially from the top surface 308 of the bit holder 300 to the distal end 318 of the shaft 304 and includes a counterbore 332 adjacent the top surface 308 of the bit holder 300. In the illustrated embodiment, the central bore 330 tapers outwardly as it extends from the generally central second portion 326 toward the distal end 318 of the shaft 304. In this exemplary embodiment, the taper of the bore 330 is at an angle B relative to the centerline 334 of the central bore 330. The interior angle a of the outwardly tapered portion 322 is an acute angle greater than the centerline 334 of the central bore 330. The internal angle a and the angle B may be approximately the same value in this exemplary embodiment. The central bore 330 is adapted to receive the shaft of a drill bit (not shown). The central bore 242 and the slot 222 allow the generally C-shaped annular sidewall of the shaft 206 to radially contract when the shaft is installed in the bore 250 (fig. 20 and 21) of the base block 202 and become proximate and/or generally cylindrical at the distal end 318 of the shaft 206, the shaft 304 of the drill bit holder 300 being inserted into the distal end 318 of the shaft 206 and retained therein by an outward radial force when in use. Other base block configurations may be used without departing from the concept of this design.

Eighth illustrated embodiment of a drill bit holder

Referring to fig. 30-33, an eighth embodiment of a drill bit holder 400 is shown. The bit holder 400 includes a nose or bit holder body 402, and a generally cylindrical hollow shaft 404 that depends axially from the bottom of the nose 402. Shaft 404 of drill bit holder 400 of the eighth embodiment is shorter than the approximately 2-3/4 inch generally standard length shaft of a standard drill bit holder, in this exemplary implementation, the length of shaft 404 of drill bit holder 400 is approximately nominally 1-3/4 inches. This design can also be successfully implemented with shafts of various lengths. In this exemplary implementation of the eighth illustrated embodiment, the nose 402 is generally annular in shape and includes a frustoconical portion 406 extending axially from a top surface 408 (e.g., a flat annular top surface), and a generally cylindrical tire portion 410 extending axially from the frustoconical portion 406. A chamfered surface 412 extends from the bottom of the tire portion 410 to a rear flange 414, which may be generally annular.

The shaft 404 includes an elongate first slot 416 extending axially upward or forward from a distal end 418 (e.g., a generally annular distal end) of the shaft 404 to an upper terminal end 420 near an upper or forward end of the shaft 404. In another embodiment, the shaft 404 may also include an internally oriented second slot (not shown) positioned approximately 180 degrees around the annular shaft 404 relative to the first slot 416. This second slot may be parallel to the first slot 416 and may be an internal slot having a rearward terminal end (not shown) facing inwardly adjacent the distal end 418 of the shaft 404 and a forward terminal end (not shown) longitudinally and axially generally coincident with the upper terminal end 420 of the first slot 416.

In the embodiment shown here, the shaft 404 also includes a lower or first tapered portion 422 that extends axially from a stepped shoulder 424 near the distal end 418 of the shaft 404. The stepped shoulder 424 increases or rises as it extends axially from the distal end portion 424 of the shaft 404 near the distal end 418 of the shaft 404 to the lower tapered portion 422. The lower tapered portion 422 extends upwardly or axially from a stepped shoulder 424 of the shaft 404 and terminates longitudinally in a generally central slot 416. The shaft 404 also includes an annular shoulder 428 that separates the lower tapered portion 422 from the second tapered portion 430. An annular shoulder 428 is disposed between the first tapered portion 422 and the second tapered portion 430. The diameter of the annular shoulder 428 decreases or decreases as it extends axially from the first tapered portion 422 to the second tapered portion 428. The second tapered portion 430 of the shaft 404 extends from a location near the annular shoulder 428 toward the rear flange 414 representing the base or bottom of the nose 402 of the bit holder 400. The top of the shaft 404 may include a rounded junction 432 between the second tapered portion 430 of the shaft 404 and the back flange 414 of the nose 402 of the drill bit holder 400 in order to avoid sharp corners that may provide areas where stress cracks initiate. In other embodiments, shaft 404 may comprise different configurations, for example, lower portion 422 and/or upper portion 430 of shaft 404 may comprise a generally cylindrical shape, an outward taper, an inward taper, a slight stretching angle, or a slight pulling angle.

A central bore 434 extends axially from the top surface 408 of the bit holder 400 to the distal end 418 of the shaft 404, and includes a counter bore 436 adjacent to the top surface 408 of the bit holder 400. In this illustrated embodiment, the central bore 434 tapers outward as it extends from the generally central second portion 428 toward the distal end 418 of the shaft 404, similar to the taper shown in fig. 26. The central bore 434 is adapted to receive the shaft of a drill bit (not shown). The central bore 434 and slot 416 allow the generally C-shaped annular sidewall of the shaft 404 to radially contract when the shaft is installed in the bore of the base block and become approximately and/or generally cylindrical at the distal end 418 of the shaft 404 and retained by an outward radial force when in use. Other base block configurations may be used without departing from the concept of this design.

Ninth illustrated embodiment of a drill bit holder

Referring to fig. 34-37, a ninth embodiment of a drill bit holder 500 is shown. The bit holder 500 includes a nose or bit holder body 502, and a generally cylindrical hollow shaft 504 that depends axially from the bottom of the nose 502. The shaft 504 of the drill bit holder 500 of the ninth embodiment is shorter than the approximately 2-3/4 inch generally standard length shaft of a standard drill bit holder, in this exemplary embodiment the length of the shaft 504 of the drill bit holder 500 is approximately nominally 1-3/4 inches. This design can also be successfully implemented with shafts of various lengths. In this exemplary implementation of the ninth illustrated embodiment, the nose 502 is generally annular in shape and includes a frustoconical portion 506 extending axially from a top surface 508 (e.g., a flat annular top surface), and a generally cylindrical tire portion 510 extending axially from the frustoconical portion 506. A chamfer 512 extends from the bottom of the tire portion 510 to a rear flange 514, which may be generally annular.

Shaft 504 includes an elongate first slot 516 that extends axially upward or forward from a distal end 518 (e.g., a generally annular distal end) of shaft 504 to an upper terminal end 520 near the upper or forward end of shaft 504. In another embodiment, shaft 502 may also include an internally oriented second slot (not shown) positioned approximately 180 degrees about annular shaft 504 relative to first slot 516. This second slot may be parallel to first slot 516 and is an internal slot having a rearward terminal end (not shown) facing inwardly adjacent distal end 518 of shaft 504 and a forward terminal end (not shown) longitudinally and axially generally coincident with upper terminal end 520 of first slot 516.

In this illustrated embodiment, the shaft 504 also includes a lower or first outwardly tapered portion 522 that extends axially from a stepped shoulder 524 near the distal end 518 of the shaft 504. The stepped shoulder 524 increases or rises as it extends axially from the distal end portion 526 of the shaft 504 near the distal end 518 of the shaft 504 toward the lower, outwardly tapered portion 522. A lower outwardly tapered portion 522 extends upwardly or axially from a stepped shoulder 524 of shaft 504 and terminates longitudinally in a generally central groove 516. Shaft 504 also includes an annular shoulder 528 that separates lower outwardly tapered portion 522 from an upper or second tapered portion 530, which upper or second tapered portion 530 extends from shoulder 528 to generally near the top of shaft 504. An annular shoulder 528 is disposed between the first outwardly tapered portion 522 and the second tapered portion 530. The diameter of the annular shoulder 528 decreases or decreases as it extends axially from the first outwardly tapered portion 522 to the second tapered portion 530. A generally cylindrical top portion 532 of the shaft 504 extends from a location near the second tapered portion 530 toward a rear flange 514 representing the base or bottom of the nose 502 of the bit holder 500. The top of the shaft 504 may include a rounded joint 534 (fig. 34, 36, and 37) between the top portion 532 of the shaft 504 and the back flange 514 of the nose 502 of the drill bit holder 500, in order to avoid sharp corners that may provide areas where stress cracks initiate. In other embodiments, shaft 504 may comprise different configurations, for example, lower portion 522 and/or upper portion 530 of shaft 504 may comprise a generally cylindrical shape, an outward taper, an inward taper, a slight draft angle, or a slight draft angle.

A central bore 536 extends axially from the top surface 508 of the bit holder 500 to the distal end 514 of the shaft 504 and includes a counter bore 538 adjacent to the top surface 508 of the bit holder 500. In this illustrated embodiment, central bore 536 tapers outwardly as it extends from generally central second portion 530 to distal end 518 of shaft 504, similar to the taper shown in fig. 26. The central bore 536 is adapted to receive a shaft of a drill bit (not shown). The central bore 536 and the slot 516 allow the generally C-shaped annular sidewall of the shaft 504 to radially contract when the shaft is installed in the bore of the base block, causing the shaft 504 and the bore 536 to become approximately and/or generally cylindrical and retained by an outward radial force when in use. Other base block configurations may be used without departing from the concept of this design.

Seventh illustrated embodiment of a bit holder and fourth illustrated embodiment of a base block

Referring to fig. 38-41, a seventh embodiment of a drill bit holder 300 and a fourth embodiment of a base block 600 as described above are shown. A fourth embodiment of a pedestal block 600 includes a pedestal mounting portion 602 that includes a pedestal 604, which pedestal 604 may be flat (as shown) or slightly recessed to fit over a cylindrical barrel (not shown), or mounted to a pedestal or riser mounted on the barrel; and a generally annular and/or cylindrical bit holder receiving portion 606 adjacent to the base mounting portion 602 that holds the base block 600 on the barrel. The receiving portion 606 includes a central aperture 608 that extends axially from a front face 610 of the receiving portion 606 to a recess 612 near the base 604 of the base mounting portion 602 of the base block 600. Bore 608 includes a counterbore 614 adjacent front face 610. The bore 608 of the base block 600 is adapted to receive the shaft 304 of the drill bit holder 300 into which the shaft 304 of the drill bit holder 300 is inserted and retained by outward radial forces when in use, as shown in fig. 39, and the bore 330 of the drill bit holder 300 is adapted to receive the shaft 616 of the drill bit 618. Other base block configurations may be used without departing from the concept of this design.

When in use, the central bore 330 and the slot 316 allow the generally C-shaped annular sidewall of the shaft 304 to radially contract when the shaft is installed in a bore of a base block (such as the bore 608 of the base block 600), as shown in fig. 40 and 41. As shown in fig. 40, the ability of the slotted shaft 304 to change its shape enables a more complete surface fit or contact between the shaft 304 and the hole 608 of the base block 600. Thus, the bit holder 300 remains tightly mounted in the bore 608 of the base block 600 and the service life of the bit assembly 620 (fig. 39) is extended. Referring to fig. 41, after the drill bit holder 300 is inserted into the bore 608 of the base block 600, the central bore 330 becomes less tapered outward toward the distal end 318 (shown at J, K and L in fig. 41) and becomes generally cylindrical and/or annular in shape.

As used in this application, the term "or" is intended to mean an inclusive "or" rather than an exclusive "or". That is, unless specified otherwise, or clear from context, "X comprises a or B" is intended to mean any of the natural inclusive permutations. That is, if X contains A; x comprises B; or X comprises A and B, then "X comprises A or B" is satisfied under any of the foregoing instances. Further, "X comprises at least one of a and B" is intended to mean any natural inclusive permutation. That is, if X contains A; x comprises B; or X comprises A and B, then "X comprises at least one of A and B" is satisfied under any of the foregoing instances. The articles "a" and "an" as used in this application and the appended claims should generally be construed to mean "one or more" unless specified otherwise or clear from context to be directed to a singular form. Moreover, the use of the term "an embodiment" or "one embodiment" throughout is not intended to refer to the same embodiment, aspect, or embodiment unless so described.

While the disclosure has been described in connection with certain embodiments and measurements, it is to be understood that the disclosure is not limited to the disclosed embodiments and measurements, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the scope of the appended claims, which scope is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures as is permitted under the law.

Claims

1. A drill bit holder, comprising:

a body portion including a body axial length;

a generally cylindrical hollow shaft depending axially from a bottom of the body portion, the shaft including a shaft axial length that is longer than the body axial length; and

an outer surface of a first portion of the shaft adjacent a distal end of the shaft tapers radially outward as it extends toward the distal end.

2. A drill bit holder according to claim 1, further comprising:

a slot through a sidewall of the shaft, the slot extending from the distal end of the shaft.

3. A drill bit holder according to claim 2, further comprising:

an upper terminal end of the slot disposed adjacent to a front end of the shaft.

4. A drill bit holder according to claim 1, further comprising:

a slot through a sidewall of the shaft, the slot extending from a rearward position adjacent the distal end of the shaft to a forward position adjacent a forward end of the shaft.

5. A drill bit holder according to claim 1, further comprising:

a bore extending axially from a front end of the body portion to the distal end of the shaft.

6. A drill bit holder according to claim 1, further comprising:

a length of the shaft comprising one of a standard length and a shortened length, the shortened length being shorter than the standard length.

7. The drill bit holder of claim 6, wherein the standard length is nominally 2-3/4 inches and the shortened length is nominally 1-3/4 inches.

8. A drill bit holder according to claim 5, further comprising:

a portion of the bore comprising a radially outward taper as the portion extends toward the distal end of the shaft.

9. A drill bit holder according to claim 1, further comprising:

a second portion of the shaft adjacent the first portion, the second portion comprising a radially inward taper as the second portion extends toward the first portion.

10. A drill bit holder according to claim 5, wherein the length of the shaft is based on the diameter of the bore.

11. A combined drill bit holder and base block, comprising:

a drill bit holder, comprising:

a body portion including a body axial length;

an outer surface of a first portion of the shaft adjacent a distal end of the shaft that tapers radially outward as it extends toward the distal end; and

a base block, comprising:

a base mounting portion including a bottom surface;

a device receiving portion integrally extending from the base mounting portion opposite the bottom surface; and

a base block bore extending through the device receiving portion, the base block bore adapted to receive the shaft of the bit holder.

12. The combined drill bit holder and base block of claim 11, further comprising:

13. The combined drill bit holder and base block of claim 12, further comprising:

14. The combined drill bit holder and base block of claim 11, further comprising:

15. The combined drill bit holder and base block of claim 11, further comprising:

a bit holder bore extending axially from a front end of the body portion to the distal end of the shaft.

16. The combined drill bit holder and base block of claim 11, further comprising:

17. The combined bit holder and base block of claim 16, wherein the standard length is nominally 2-3/4 inches and the shortened length is nominally 1-3/4 inches.

18. The combined drill bit holder and base block of claim 15, further comprising:

a portion of the bit holder bore comprising a radially outward taper as the portion extends toward the distal end of the shaft.

19. The combined drill bit holder and base block of claim 11, further comprising:

an axial length of the device receiving portion that is shorter than a length of the base mounting portion.

20. The combined drill bit holder and foot block of claim 19, the foot mounting portion comprising an extension of an arcuate section of the foot block bore that extends through a rear of the device receiving portion to a position adjacent to a rear of the foot mounting portion.

21. The combination drill bit holder and foot block of claim 20, the extension of the arcuate section of the foot block bore forming an interference fit with the first portion of the shaft, wherein the shaft length is nominally 2-3/4 inches.

22. The combined drill bit holder and base block of claim 19, further comprising:

an angular slot extending inwardly from the rear of the device receiving portion, the angular slot fitting within a sidewall of the device receiving portion at a location centered on a front of the device receiving portion and the rear of the device receiving portion.

23. The combined drill bit holder and base block of claim 11, further comprising:

24. The combination drill bit holder and pedestal block of claim 19, wherein the pedestal block bore comprises an axial length of about 1-1/2 inches and a nominal diameter of 1-1/2 inches.

25. The combined bit holder and base block of claim 15, wherein the length of the shaft is based on a diameter of the bit holder bore.