Material removing tool for road milling mining and trenching operations

Abstract

An improved tool is described that has a generally cylindrical slotted shank with a radially bulbous or extending portion adjacent a distal end of the shank, sized to interfere with a bore in which the shank is to be inserted. The dimension of the extending portion can be sized to change the retention force between the shank and the bore as desired. A top of the tool includes a metal carbide-metal disk-metal carbide diamond coated tip sandwich that is bonded inside a bore in the top of the tool.

Description

TECHNICAL FIELD

This disclosure relates generally to road milling, mining and trenching equipment and, more particularly, to replaceable hardened tip tools or bits that are utilized at the leading edge of such equipment where material removal initially takes place.

BACKGROUND

Tools or bits have historically been selectably removably retained in tool holders, base blocks, and the like. When they are worn out, they may be driven from their mountings and replaced by new or reconditioned such tools. Such a tool with a hardened tip can be found in applicant's prior U.S. Pat. No. 6,739,327. For some time, such cutting tools have had hardened tips, preferably made of tungsten carbide.

More recently, the use of diamond material, either industrial or manmade, as coatings or layers on the tips of the inserts, preferably still made of tungsten carbide, have found their way into material removing equipment. Tungsten carbide tipped tools have generally been rotatable in their bit holders or base blocks. The use of longer lasting diamond tipped inserts has for some operations given way to a one piece tool-bit holder combination, sometimes called a pick. With such a pick, the diamond tipped insert is integrally formed at the top of the bit holder which, in turn, is selectably removeably mounted in a base block.

The additional working life of the diamond tipped inserts has meant that generally longer use life could be had without needing rotatability of the tools. However, at present, the layering or coating of such diamond material on insert bases has proven not to be usable in all such material removing instances. While such diamond tipped tools may be usable to remove the top of long stretches of straight highway materials, such diamond tipped tools have not been so successful in removing material from concrete surfaces. This has necessitated changing the entire set of picks (or bit/holder combinations) from a drum when removing portions of certain stretches of highway segments. Aside from changing out the picks on an entire drum, which include potentially hundreds of picks, there also exists the potential of maintaining multiple drums, some having diamond tipped inserts mounted on the drums and others having tungsten carbide tipped inserts mounted on the drums. The added costs in downtime, changing picks, and/or in capital in maintaining multiple drums is substantial.

A need has developed for improved cutting tools or bits, especially diamond tipped cutting tools, that may be more easily and quickly removed and changed out of drums or endless chains utilized for mounting such tools thereon.

SUMMARY

This disclosure relates generally to bit assemblies for road milling, mining, and trenching equipment. One implementation of the teachings herein is a tool that includes a metal body and a generally cylindrical shank depending therefrom, the shank including a bulbous portion adjacent a distal end thereof, a slot in the shank extending axially upwardly from the distal end substantially through the bulbous portion thereof and inwardly from a side wall thereof toward a maximum diametrical dimension of an inner bore in the shank.

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

BRIEF DESCRIPTION OF THE DRAWINGS

The various features, advantages, and other uses of the apparatus will become more apparent by referring to the following detailed description and drawings, wherein like reference numerals refer to like parts throughout the several 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.

FIG. 1 is an exploded perspective view of a first embodiment of the bit having a reverse taper shank constructed in accordance with the present disclosure;

FIG. 2 is an exploded side elevational view of the bit as shown in FIG. 1;

FIG. 3 is a front elevational view of the bit shown in FIG. 1 assembled with its steel plug intact;

FIG. 4 is a front elevational view of the bit showing its steel plug reduced to a thin disc;

FIG. 5 is a front elevational view of a completely assembled bit;

FIG. 6 is a front elevational view of a second embodiment of the bit of the present disclosure;

FIG. 7 is a fragmentary elevational view of a first modification of the shank distal end showing a convex bulbous feature; and

FIG. 8 is a fragmentary elevational view of a second modification of the shank distal end showing a forward taper bulbous feature.

DETAILED DESCRIPTION

Referring to FIGS. 1 and 2, a first embodiment of a tool or bit 10, constructed in accordance with the present disclosure, suitable for use in road milling, mining and trenching operations, includes a steel body 11, an annular tungsten carbide shield 12 mounted on a generally cylindrical upper or top portion 13 of the body, a tungsten carbide plug 14, a steel plug 15 (to be modified as disclosed hereafter), and a hardened tip 16. In this first embodiment, the hardened tip 16 has a diamond material layer or coating 17 and a tungsten carbide substrate or base 18. The diamond material may be polycrystalline diamond (PCD), industrial diamond, or a solid or layered thermally stable polycrystalline diamond (TSP).

The main body 11 of the tool 10, that in this first embodiment is preferably made of steel, includes the generally cylindrical top portion 13 that has an annular uppermost surface 20 with a central bore 21 extending therein part way along the length of the top of the generally cylindrical top portion 13. A frustoconical base 22 of the top portion 13 extends downwardly and outwardly forming the inside of an annular trough 23 in what would be termed a tire portion 24, or washer portion, i.e., the largest outer diameter portion of the tool or bit 10. The annular trough 23 has a substantially flat annular bottom in this first embodiment. The tire portion 24 also includes a vertical annular wall 25. The tire portion 24 or base is generally solid and extends downwardly to a chamfer 26 (FIG. 2) defining the outside of a rear annular flange 27.

Descending from the rear annular flange 27 is a generally cylindrical shank 28, about 25/32 inch in diameter, although variations in shank diameters are found, 1½ inch on the low end, and larger on mining and trenching equipment. The shank 28 is solid along an upper portion of same and has, adjacent a distal end 30 of the shank 28, generally a bulbous portion. In this first embodiment, the shank 28 includes a reverse taper or expanding skirt portion 31 adjacent the distal end 30, with the generally annular distal end 30 of the shank 28 being slightly smaller than the widest bottom portion 31a of the skirt portion 31. The shank 28 further includes a bore 32 extending generally inwardly of the distal end 30 thereof, up through the reverse taper or skirt portion 31 of the tool 10. The bore 32 is contiguous with a slot 33 (FIGS. 3-5) extending to the outer surface of the reverse taper or skirt portion 31 of the shank 28.

The interference fit provides a shank to bore connection that prevents bit rotation during use, but still allows for a manual rotation by gripping the outer diameter of the tire portion 24 with a pipe wrench type of tool (not shown) to cover an index of the bit. An index of 180 degrees of the PCD bit tip 16 will present an unused diamond tip surface portion to contact the material to be removed.

In this first embodiment of the tool or bit 10, the outer diameter of the washer or tire portion 24 is about 2 inches and is larger than the diameter of the nose of a bit holder (not shown) into which the tool or bit 10 is inserted. The shank 28 has an overall length approximating 1⅝ inches and the reverse taper portion 31 is about ¾ inch in vertical length or height.

The protective member, shield or shroud 12 positioned or mounted adjacent the top of the bit or tool upper portion 13, is an annular tungsten carbide shroud. In this first embodiment, the annular tungsten carbide shroud 13 includes an annular bottom flange 34 having a vertical side surface 35, a curved inwardly extending side wall 36 upwardly thereadjacent, and a hollow cylindrical upper portion 37. The hollow upper portion 37 is defined by a bore 38 centrally therethrough and adjacent the bottom of the bore 38 is a hollow frustoconical portion 40. This hollow portion, the bore 38 and the hollow frustoconical portion 40, is matingly complementary to the upper portion 13 of the tool body 11 above the washer or tire portion 24. The bottom flange 34 of the protective member 12 fits in the annular trough 23 of the washer or tire portion 24 of the tool 10.

As shown in FIGS. 1 and 2, the tungsten carbide shield or shroud 12 is sized to be fitted on and brazed to the upper portion 13 of the tool body 11. The generally cylindrical tungsten carbide plug 14, positioned above the annular tungsten carbide shroud 12 as shown, is sized to be complementarily fitted (brazed) into the bore 21 extending axially inwardly from the top 20 of the generally cylindrical upper portion 13 of the tool body 11, to be discussed in more detail below. This tungsten carbide plug 14 provides added stiffness to the upper portion 13 of the bit or tool body 11 while also adding strength and toughness to the central part of the upper portion 13 of the tool body 11.

Additionally, this generally cylindrical tungsten carbide plug 14 is less expensive to make than would be a bit tip or insert with a hardened coating or layer positioned on top thereof that had a cylindrical body of the length of the combined bit tip with the tungsten carbide plug. Therefore, the hardened insert or tip 16 utilized can be a commercially available product.

The generally cylindrical steel plug 15 is positioned between the insert or bit tip 16, with the hardened layer or coating 17 on top of the tungsten carbide generally cylindrical base 18 and the tungsten carbide plug 14, as shown in FIG. 1. This generally cylindrical steel plug 15 will be utilized during the assembly of the components of the tool 10 and will be modified as to be discussed in more detail below.

Referring to FIGS. 3-5, the assembly of the components shown in FIGS. 1 and 2 is shown in greater detail. In step 1, shown in FIG. 3, the body 11 of the bit or tool 10 has the generally annular tungsten carbide shroud 12 fitted over the generally cylindrical upper portion 13 of the body 11 and has a brazing ring (not shown) positioned in the trough 23 of the washer or tire portion 24 of the tool 10. The tungsten carbide plug 14 is positioned in the bore 21 through the top 20 of the upper portion 13 of the body 11 of the tool 10 and has a first brazing disk 42 positioned on a bottom 41 of the bore 21. The steel plug 15 is positioned in the top of the bore 21 and further includes a second brazing disk 43 positioned between the bottom of the steel plug 15 and the top of the tungsten carbide plug 14. In FIG. 3, the steel plug 15 extends outwardly of the bore 21 of the upper portion 13 of the bit or tool body 11 when initially inserted therein.

The entire assembly, as shown in FIG. 3, minus the bit tip or insert 16, is heated to a temperature of about 1,800 degrees Fahrenheit (“F”), wherein the brazing material melts or becomes a liquid and adheres the separate components together in a unitary structure.

It should be noted that the use of the steel plug 15, being brazed to the top of the tungsten carbide plug 14, provides a greater adherence thereto than if the tungsten carbide plug 14 would be brazed to the bottom of the tungsten carbide base 18 of the bit tip or insert 16. After the assembly of the parts in step 1 is completed, the entire tool is heat treated to a hardness of RC 40-50.

Referring to step 2 in FIGS. 4 and 5, the steel plug 15 at the top of the tool or bit 10 upper portion 13 is thereafter largely removed from the tool 10, by cutting, boring or otherwise removing most of the steel plug 15 until only approximately a 0.030 inch thick disk 15a (FIG. 5) remains brazed to the top of the tungsten carbide plug 14. Thereafter, the commercially obtainable insert or tip 16 which, in this embodiment includes the generally cylindrical tungsten carbide substrate 18 with the PCD or diamond coating or layer 17 positioned on the top thereof with a flat, rounded or cone shaped leading surface, is combined with a third brazing disk 44 to braze same on top of the now 0.030 inch thick steel disk 15a. This provides a tungsten carbide-steel-tungsten carbide sandwich which, when brazed together, is stronger than would be the combination of brazing the tungsten carbide plug 14 to the tungsten carbide base 18 of the hardened tip 16.

Also, in order to maintain the integrity of the coating or layer 17 on the top of the tip or insert 16, this additional brazing operation is carried out at a lower temperature than the initial brazing operation by cooling the tool body to a temperature below that which would cause harm to the diamond impregnated material on the impact tip. This additional brazing operation of the hardened tip 16 is carried out at approximately 1,300 degrees F. or less.

FIG. 5 discloses the final product of the tool body with the annular shroud 12 brazed to the top of the outside of the upper portion 13 thereof and the tungsten carbide plug 14 brazed to the inside of the bore 21 of the upper portion 13, with about a 0.030 inch thick steel disk 15a brazed on the top of the tungsten carbide plug 14 and, in turn, brazed to the base 18 of the coated tip or insert 16.

The combination sandwich of the tungsten carbide plug 14, the steel disk 15a and the tungsten carbide substrate 18 with the preferably diamond material coated tip 17 of the tip or insert 16, provides not only a stronger central portion of the upper portion 13 of the tool 10, but also provides a structure which is substantially less expensive by utilizing a commercially obtainable insert 16 with the tungsten carbide plug 14. If an tip or insert were to be formed having the total height of the sandwich shown in FIG. 5, it would be substantially more expensive than the present structure.

An additional benefit is obtained utilizing the steel disk 15a in the tungsten carbide-steel-tungsten carbide sandwich in that the steel disk 15a has an expansion ratio (i.e., coefficient of expansion) that is higher than tungsten carbide so when the bit or tool 10 is utilized in service, the operating temperature of the tool 10 will rise when frictionally removing material to about 700-800 degrees F. With this increase in temperature, the steel disk 15a expands radially outwardly at about 150 percent of the rate of the tungsten carbide plug 14 and tungsten carbide substrate 18, thus providing not only greater brazing adherence in the sandwich, but also a tighter axial stiffness between the carbide plug 14, the steel disk 15a and the PCD insert 16 at the upper portion 13 of the tool body 10.

Referring to FIG. 6, a second embodiment of the bit or tool 50 of the disclosure is shown. The tool 50 includes a shank 51 having a reverse taper portion 51a, substantially similar to that shown in the first embodiment and a washer or tire portion 52 of the tool 50 being substantially similar to that shown in the first embodiment of the tool 10. However, an upper body portion 53 of the tool 50 generally has a larger diameter at a base 54 of the upper body portion 53 than the upper portion 13 of the tool 10 of the first embodiment, a smaller solid chamfer transition 55 than the frustoconical portion 40 of the tungsten carbide shield 12 of the tool 10 shown in the first embodiment, and a larger generally cylindrical solid upper body portion 53. The topmost portion of the upper body portion 53 thereafter transitions frustoconically to an annular top 56, similar to the diameter of the top 20 of the upper portion 13 of the tool 10 as shown in the first embodiment. Likewise, the second embodiment of tool 50 includes the sandwich of a tungsten carbide plug 57, a steel disk 58, and a hardened tip or insert 60 with a tungsten carbide substrate or base 71 with has a hardened material layer or coating 72 at the top thereof, similar to that shown in FIG. 5, which is coated with preferably a PCD or diamond material.

The generally annular protective tungsten carbide shroud 61 shown in the tool 50 of the second embodiment has a somewhat differing shape than that shown in the tungsten carbide shield 12 of the tool 10 of the first embodiment. It has an annular generally rounded profile top 62 and a tapering frustoconical side 63 extending downwardly and outwardly to the washer or tire portion 52 of the tool 50. The hollow interior 64 of the shroud 61 is shaped to complementarily conform to the shape of the upper body portion 53, which in this embodiment is made of steel, of the tool body. The tool 50 of the second embodiment of the present disclosure is assembled in the same manner as shown in FIGS. 3-5 with the tool 10 of the first embodiment.

Referring to FIGS. 7 and 8, a first modification 59 and a second modification 59a of the tool 10, 50 of the present disclosure include a generally bulbous reverse taper portion adjacent a distal end 65 of the shank 66, 66a, respectively. The shank 66 of the first modification 59, shown in FIG. 7, includes a convex shape bulbous portion 67 adjacent the distal end 65 of the shank 66. The shank 66a of the second modification 59a, shown in FIG. 8, includes an expanded top tapered portion 68 adjacent the distal end 65 of the shank 66a. The expanded top tapered portion 68, as shown in FIG. 8, turns out to be a normally tapered portion, but with the top extending outwardly of the rest of the shank 66a, in reverse to what would be considered a reverse taper portion 31 shown in the tool 10 of the first embodiment and the tool 50 of the second embodiment.

It should be noted that generally, heretofore, tools or bits have included an annular retainer (not shown) around the outside of the shank of the tool which, generally made of sheet metal, would be somewhat radially compressible in a reduced diameter or cutout section of the shank and by compressing same and putting same in a tool holder bore, would exert some outward pressure to maintain the tool within the tool holder bore (not shown). Those tools have heretofore been generally configured to be rotatable in the bit holder bore.

With the present disclosure, the dimension of the reverse taper portion 31, 51a of FIGS. 1-5 and 6, respectively, the convex shape bulbous portion 67 of FIG. 7, and what would be the outsized taper portion 68 of FIG. 8 may be variously dimensioned depending upon what amount of retention or diametrical force is desired between the bit or tool shank and the bit holder bore.

Generally, bit holder bores are nominally 25/32 inch in diameter with the shank being sized to be rotatable therein and restrained somewhat therein by a sheet metal retainer positioned around the outside of the shank. With the present disclosure, the outer diameter, especially of the largest portion of the reverse taper shank may approximate 0.80 to about 0.85 inch in diameter and provide sufficient radial force such that the tool does not rotate in the bit holder bore. This would be preferable as long as the coating or layer on the tip or insert is of PCD or industrial diamond material.

Likewise, the convex shape bulbous portion 67 configuration shown in FIG. 7 may have an outer diameter that retains the bit shank in the bit holder bore with an interference fit. Additionally, the skirt may be sized to be partly rotatable, that is, rotatable (perhaps in 90 degree increments) with a tool such as a channel lock or the like. Further, the skirt may be large enough to fit in that portion between the shank and the bit holder bore such that the tool would not rotate therein.

All these configurations are intended to be utilized with a conventional straight bit holder bore. Within the spirit of the disclosure, additional configurations of the bit holder bore may be found to be practical when utilized with the various modifications of the bit shank shown herein.

Another feature of the present disclosure is the provision of PCD, TSP or industrial diamond tips in hardened bits or tips of tools that may be more easily removable from drums or chains than is heretofore possible with integrally formed bit and bit holders. These are sometimes termed picks that are mountable in base block bores similarly to that of bit holders and which are non-rotatable by design. With prior art tools or bits, or with such picks, entire drums completely outfitted with PCD, TSP or diamond tip picks, have been heretofore utilized on straight portions of highways and the like, with separate drums completely outfitted with tungsten carbide bits used for more severe work such as concrete removal.

The tool or bit described in various embodiments of the instant disclosure enables one to quickly change from tungsten carbide tip bits to diamond tip tools on a single drum enabling quick transitions without substantial down time when removing material from different configurations of highways. Changes from tungsten carbide tip bits to PCD, industrial diamond, or TSP tip bits and vice versa, quickly, even multiple times during a day.

While the present disclosure has been described in connection with certain embodiments, it is to be understood that the disclosure is not to be limited to the disclosed embodiments 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 tool comprising: a metal body comprising a top that includes a bore extending axially inwardly from the top;a shank depending from a bottom of the metal body;a metal carbide plug positioned wholly within said bore and bonded in the bore;a metal disk bonded to a top of the metal carbide plug; andan impact tip being bonded to a top of the metal disk, the impact tip extending outwardly of the top of the metal body.

2. The tool as defined in claim 1, wherein bonded includes brazing.

3. The tool as defined in claim 1, wherein the metal disk starts out as a metal plug extending outwardly of the top of the metal body.

4. The tool as defined in claim 1, wherein the metal disk has a coefficient of expansion that is greater than that of the metal carbide plug, thereby providing greater rigidity to said metal body when in use.

5. The tool as defined in claim 1, wherein the metal disk is heat treated after the metal disk is bonded to the top of the metal carbide plug.

6. The tool as defined in claim 1, wherein the metal (steel) disk forms a sandwich structure with the metal carbide plug immediately below the metal disk and a metal carbide base of the impact tip above the metal disk on the tool.

7. The tool of claim 1, further comprising: a metal carbide shield mounted to the top of the metal body.

8. A method of making the leading end of a tool body comprising the steps of: bonding a metal carbide plug wholly within a bore in a top of the tool body;bonding a metal plug to a top of the metal carbide plug in the bore;heat treating the top of the tool body;removing a portion of the metal plug from the tool body, thereby leaving a residual disk in the bore; andbonding an impact tip to a top of the residual disk with the tip extending outwardly of the top of the tool body.

9. The method of claim 8, wherein said heat treating is carried out at a higher first temperature than bonding the impact tip to the top of the metal plug, wherein the bonding of the impact tip is carried out at a second temperature lower than the higher first temperature.

10. The method of claim 8, further comprising the step of: cooling said tool body to a temperature below that which would cause harm to a diamond impregnated material on the impact tip after the step of heat treating the top of the tool body.

11. The method of claim 8, further comprising: mounting a metal carbide shield to said top of the tool body before bonding the metal carbide plug in the bore in said top of the tool body.

12. A method of making the leading end of a tool body comprising the steps of: bonding a metal carbide plug wholly within a bore in a top of the tool body;bonding a metal plug to a top of the metal carbide plug in the bore;heat treating the top of the tool body;removing a portion of the metal plug from the tool body after heat treating the top of the tool body, thereby leaving a residual disk bonding an impact tip to a top of the residual disk with the tip extending outwardly of the top of the tool body.

13. The method of claim 12, wherein said bonding of at least one of the metal carbide plug, the metal plug, and the impact tip comprises brazing.

14. The method of claim 12, wherein removing comprises boring.

15. The method of claim 12, wherein removing comprises drilling.

16. The method of claim 12, wherein removing comprises cutting.

17. The method of claim 12 wherein said heat treating is carried out at a higher first temperature than bonding the impact tip to the top of the metal plug, wherein the bonding of the impact tip is carried out at a second temperature lower than the higher first temperature.

18. The method of claim 12 further comprising the step of: cooling said tool body to a temperature below that which would cause harm to a diamond impregnated material on the impact tip of the step of heat treating the top of the tool body.

19. The method of claim 12 further comprising: mounting a metal carbide shield to said top of the tool body before bonding the metal carbide plug in the bore in said top of the tool body.