Bit holders and bit blocks for road milling, mining and trenching equipment
An improved bit holder with its mating bit block is disclosed utilizing a slight taper in the bit block bore, and a tapered shank on the bit holder that includes a second larger diameter tapered distal segment that combines with an axially oriented slot through the side wall of the bit holder shank to allow a substantially larger interference fit between the distal tapered shank segment and the bit block bore than previously known. When inserting the bit holder in the bit block bore, the distal first tapered segment resiliently collapses to allow insertion of that segment into the bit block bore. A second shank tapered portion axially inwardly of the first distal tapered portion. The dual tapered shank allows the insertion of the bit holder in the bit block with an interference fit that provides a secure mounting of the bit holder in the bit block.
This application is a divisional of Ser. No. 09/500,983 filed Feb. 15, 2000, now U.S. Pat. No. 6,371,567, which is a continuation in part of Ser. No. 09/273,690 filed on Mar. 22, 1999, now U.S. Pat. No. 6,364,420.
This invention relates generally to road surface removal or reclaimer-stabilizer equipment and mining equipment, and more particularly, to cutter bit holders and bit blocks used in such road milling, mining, and trenching equipment.
BACKGROUND OF THE INVENTIONCutter bits are utilized in road, off-road and mining machinery on the perimeter and across the width of a rotary drum or on the outside of a continuous chain or the like where the bits are moved through an orbit which is intercepted by the face of the material being removed or recycled. Road milling equipment removes the defective surface of a road and smooths the top of all or selected portions of the road surface. The bits include a tip and a shank. The shank is received and may axially rotate in a bit holder which is secured onto a bit block that, in turn, is mounted on the drum. Each of the bits has a hardened tip, preferably made of tungsten carbide or such other hardened material that acts to remove a portion of the surface it contacts. By using a sufficient number of these bits around the outer surface of a rotating drum, a large amount of surface may be worked. Any surface being worked generally has a hardness which can be measured or anticipated prior to the removal operation. However, such road surfaces, or surfaces being removed have hardened irregularities running therethrough. The toughness or hardness of the irregularities may result in the breakage of the bits and holders as they are being run over such irregularities.
Additionally, a need has developed for providing ease of removability of bits in their bit holders, especially when the bit becomes worn and in need of replacement. U.S. Pat. No. 5,374,111 discloses an undercut flange at the bottom of a base of a bit that allows a pry bar to be wedged between that flange and the top of the bit block (no bit holder in this patent) to help remove a bit from a bit block. It would be desirable to provide a more efficient means for allowing the removal of a bit from a bit holder or a bit block.
Additionally, tightening a small fastener on the bottom of a bit holder to hold it in the bit block concentrates friction forces on a small area of the nut top face and the bottom of the bit block. It would be desirable to spread those friction forces over a larger area and avoid the use of a nut to retain the bit holder on the bit block.
Further, a need has developed for a truly quick-change type of bit holder that may easily and quickly be both inserted in the bit block and removed therefrom.
It is, therefore, an object of the present invention, generally stated, to provide an improved means for quickly mounting and/or removing a bit holder from its associated bit block.
Another object of the present invention is the provision of an improved means for mounting a bit holder in a bit block without the use of retaining nuts, clips or the like.
A further object of the invention is the provision of retaining a bit holder in a bit block by means of a resilient interference fit between the holder and the block.
Another object of the invention is the provision of an improved means for providing for breakage of inexpensive replaceable parts when road resurfacing equipment and mining equipment bits encounter very hard irregularities in the surface being milled or mined.
The features of the present invention which are believed to be novel are set forth with particularity in the attached claims. The invention may best be understood by reference to the following description taken in conjunction with the accompanying drawings in which like numerals refer to like parts, and in which:
Referring to
Referring to
The bit holder 22, constructed in accordance with the present invention, includes a generally flat annular leading surface 31 on which the rear side of the bit flange 28 rests when inserted therein. Adjacent the annular leading surface 31 is a middle or tapered portion 32 that ends in an enlarged flange portion 33. In the preferred embodiment of the invention, a plurality of notches, flats or indents 32a-d extend radially inwardly of the middle tapered portion from top surface 31 toward the flange 33. The back side 34 of flange 33 is an annular flat surface which rests on the bit block 23 when mounted thereon, and includes one aspect of the present invention to be discussed below. Rearwardly adjacent the flange portion 33 is a reduced diameter cylindrical shank portion 35 and a shoulder portion 36 which may vary in length depending on its function, an undercut portion 37 is next to the shoulder portion 36, and the bit holder terminates in a threaded portion 38 adjacent the distal end 44 thereof. If the nose 26 of bit 21 hits a hard discontinuity, bit 21 will fail first, the bit holder in this embodiment may be engineered to fail next across reduced diameter section 37. The configuration allows the bit holder to tumble out of bit block bore 49 after failure.
Also shown in
The bit block 23 consists of a base portion 45 that mounts to a drum, chain, or track (not shown) and an angled bit holder mounting portion 46 extending from the base 45 that includes a top face 47, and a bottom recessed slot 48 which provides the opposing ends for a bore 49, which may be tapered, and a reduced bridging portion 51 extending from a bottom of bore 49 to the recessed slot 48. Bore 49 is sized to receive the cylindrical shank 35 of the bit holder 22 with the annular flat surface 34 on the bottom of the flange portion 33 resting on the top surface 47 of the bit block mounting portion 46. In one important aspect of the present invention, the surface area of contact between flange bottom 34 and bit block top 47 is much greater than the surface area of contact between the top 52a of nut 52 and nut contacting surface on slot 48 and will be discussed in greater detail below. The threaded portion 38 adjacent the distal end 44 of bit holder 22 extends through the reduced passageway 51 where a nut 52 may be threaded thereon by rotating the bit holder until its top surface 52a engages the surface of the recessed slot 48 to retain the bit holder 22 on the bit block 23.
Referring to
Referring to
Referring to
Flange 66 is annular in that a bore 71 runs axially through the bit holder in a more straight forward hollow cylindrical manner than the bore 40 which extends through the bit holder 22 of the first embodiment. The leading edge of bore 71 includes a countersink 72 adjacent the flat annular leading surface 62 of the bit holder to receive a similarly shaped shank portion 25 on the bit 21 shown in
In an important aspect of the present invention, a slot 81 extends through the sidewall of the shank portion from the rear semi-annular face 77 to a rounded front slot termination 82. An interference fit between the outside of tapered shank portion 73 and the like tapered bore 80 of the bit block 61 is greater than the standard interference or press fit possible if slot 81 was not in the shank portion. For example, a 1½ inch diameter shank without a slot would ordinarily have about 0.001-0.003 inch standard interference. With slot 81, the same size shank may have about 0.005-012 0.012 inch interference in the portion including the slot 81. As the distal end 77 of the shank portion 68 is positioned in the tapered bore 80 of bit block 61, the slot allows the now C-shaped portion of the shank to contract its outer diameter radially to ease the insertion of the bit holder in the bit block bore 80. This slotted portion of the shank 81 allows the C-shaped portion of the shank to act as a very strong radial spring, similarly to a hollow spring steel roll pin. The portion of shank 68 forward of slot 82 provides a 360 degree radial interference fit with the bit block bore 80, and may be greater than, equal to, or less than an interference fit at the portion of the shank at 101. The length of the slot 81 with respect to the length of the shank portion 68 may be varied depending upon the application proposed for the bit, bit holder and bit block assembly in order to optimize the operation of same. The slot 81 may, when desired, extend all the way to the rear annular flange back side 67 of the front tapered shank portion of the bit holder 60. The longer the slot, the less spring action force of shank 68. A smaller width slot provides a greater spring force. The taper for the shank 73 and bore 80 is preferably 1 degree on each side, but may be more or less, such as 2 to 4 degrees per side or ¼ to ¾ degree per side, if desired. The smaller taper such as 1 degree has a longer length of interference fit engagement and produces more radial pressure for the same axial force exerted upon it than a two degree taper for the same press fit values.
Referring to
Referring to
Referring to
The shank portion 100 is also tapered as is the shank portion 68 in
Identical smaller tapers give a longer taper contact at each end of the shank. If the angle of the taper at portion 100 is greater than the angle of the taper at portion 101, the axial length of contact between taper portion 100 and bore 80 of block 61 will be lessened. Also, a convex surface may be substituted for the tapers 100 and 101 with the result being less surface contact between the holder shank 100, 101 and block bore 80.
The shoulder 102 assures that the portion of the front taper 100 immediately adjacent the shoulder 102 does not touch the bore 80 of the bit block 61 as the bit holder is driven into the bit block. As the bit holder is further driven into the bit block and the diameter of front taper 100 increases until interference contact is made adjacent the forward end of taper 100 where the 100 percent circumferential surface is located The slot 108 decreases in width mostly in press fit zone 101 to allow the bit holder to be driven into the bit block. The position at which the front taper 100 achieves an interference fit with the bit block bore 80 is approximately that position shown in
Referring to
Referring to
In operation, the semispherical distal tip 134 is 10 positioned on the central bore 107 of the bit holder 90 at a countersink 77a (
Referring to
While four embodiments of the present invention have been shown and described, it will be apparent to those skilled in the art that changes and modifications may be made without departing from the true spirit and scope of the present invention. It is the intent of the appended claims to cover all such changes and modifications which fall within the true spirit and scope of the invention.
Claims
1. In an assembly for use in road milling, trenching and mining equipment including a bit, said bit holder and a bit block, said bit being mountable in a first bore through said bit holder and said bit holder being mountable in a second bore through said bit block, said bit holder and bit block, in combination, comprising:
- a generally frustoconical bit holder front portion terminating at an annular flange and a generally cylindrical bit holder shank portion extending axially rearwardly from said annular flange defining an annular sidewall, an elongate slot radially through said sidewall extending axially from a distal end of said shank and terminating between said distal end and said front portion defining a C-shape portion of said shank, an outer surface of said C-shape portion providing interference with said second bore on said bit block sufficient to maintain said bit holder on said bit block during use.
2. The assembly as defined in claim 1 wherein said C-shape portion of said shank is resiliently collapsible diametrically for providing said interference with said bit block bore.
3. The assembly as defined in claim 1 wherein said C-shape portion of said shank is resiliently collapsible when said bit holder is mounted on said bit block for absorbing radial forces directed to said bit holder.
4. The assembly as defined in claim 1 wherein said shank outer diameter adjacent said front portion annular flange is smaller than said bit block axial bore adjacent a top face of said bit block for allowing resilient absorption of radial forces directed to said bit holder.
5. The assembly as defined in claim 1 wherein said interference is greater than a standard press fit.
6. A bit holder for use in road milling, trenching and mining equipment as part of an assembly including a bit, said bit holder and a bit block, said bit being mountable in a first bore through said bit holder and said bit holder being mountable in a second bore through said bit block, said bit holder comprising:
- a generally frustoconical front portion terminating at an annular flange and at least one generally cylindrical shank portion extending axially rearwardly from said annular flange defining an annular sidewall, an elongate slot radially through said sidewall extending axially from a distal end of said shank and terminating between said distal end and said front portion defining at least one angular segment of said shank being less than 360 degrees in circumferential length, an outer surface of said angular segment providing interference with said second bore on said bit block sufficient to maintain said bit holder in said bit block during use.
7. The bit holder as defined in claim 6 wherein said angular segment of said shank is resiliently collapsible diametrically for providing said interference with said bit block bore.
8. The bit holder as defined in claim 6 wherein said angular segment of said shank is resiliently collapsible when said bit holder is mounted on said bit block for absorbing radial forces directed to said bit holder.
9. The bit holder as defined in claim 6 wherein said shank outer diameter adjacent said front portion annular flange is smaller than said bit block axial bore adjacent a top face of said bit block for allowing resilient absorption of radial forces directed to said bit holder.
10. The bit holder as defined in claim 6 wherein said interference is greater than a standard press fit.
11. A bit holder for use in road milling, trenching and mining equipment as part of an assembly including a bit, said bit holder and a bit block, said bit being mountable in a first bore through said bit holder and said bit holder being mountable in a second bore through said bit block, said bit holder comprising:
- a generally frustoconical front portion terminating at an annular flange and a generally cylindrical shank portion extending axially rearwardly from said annular flange defining an annular sidewall, an elongate slot radially through said sidewall extending axially from a distal end of said shank and terminating between said distal end and said front portion defining a C-shape portion of said shank, an outer surface of said C-shape portion providing interference with said second bore on said bit block sufficient to maintain said bit holder in said bit block during use.
12. The bit holder as defined in claim 11 wherein said C-shape portion of said shank is resiliently collapsible diametrically for providing said interference with said bit block bore.
13. The bit holder as defined in claim 11 wherein said C-shape portion of said shank is resiliently collapsible when said bit holder is mounted on said bit block for absorbing radial forces directed to said bit holder.
14. The bit holder as defined in claim 11 wherein said shank outer diameter adjacent said front portion annular flange is smaller than said bit block axial bore adjacent a top face of said bit block for allowing resilient absorption of radial forces directed to said bit holder.
15. The bit holder as defined in claim 11 wherein said interference is greater than a standard press fit.
16. The bit holder as defined in claim 1, wherein said bit holder further includes a means disposed in said front portion of said bit holder beginning adjacent a front face thereof to enable quick removal of said bit.
17. The bit holder as defined in claim 16, wherein said means is at least one of one of a notch, flat and detent.
18. The bit holder as defined in claim 17, wherein said at least one of said one of a notch, flat and detent is a notch.
19. The bit holder as defined in claim 18, wherein said bit holder includes a predetermined plurality of notches.
20. The bit holder as defined in claim 19, wherein said predetermined plurality of notches is at least two.
21. The bit holder as defined in claim 19, where said predetermined plurality of notches is at least three.
22. The bit holder as defined in claim 21, wherein said three notches are positioned at about 120° apart.
23. The bit holder as defined in claim 19, where said predetermined plurality of notches is at least four.
24. The bit holder as defined in claim 23, wherein said four notches are positioned at from 90° apart.
25. The assembly as defined in claim 1 wherein said interference extends from about 0.005 to 0.012 inch in a portion of said shank including said elongate slot.
3865437 | February 1975 | Crosby |
4084856 | April 18, 1978 | Emmerich et al. |
4337980 | July 6, 1982 | Krekeler |
4844550 | July 4, 1989 | Beebe |
5088797 | February 18, 1992 | O'Neill |
5106166 | April 21, 1992 | O'Neill |
5302005 | April 12, 1994 | O'Neill |
5725283 | March 10, 1998 | O'Neill |
D420013 | February 1, 2000 | Warren et al. |
6176552 | January 23, 2001 | Topka et al. |
6244665 | June 12, 2001 | Bise et al. |
6331035 | December 18, 2001 | Montgomery |
Type: Grant
Filed: Nov 1, 2005
Date of Patent: Jan 7, 2014
Inventor: Phillip A. Sollami (Herrin, IL)
Primary Examiner: Sunil Singh
Application Number: 11/264,811
International Classification: E21C 35/18 (20060101);