Mining or in situ disintegration of hard material – Cutter tooth or tooth head – Percussive tooth or bit
Reexamination Certificate
1999-10-27
2001-07-10
Bagnell, David (Department: 3673)
Mining or in situ disintegration of hard material
Cutter tooth or tooth head
Percussive tooth or bit
C299S037300, C175S414000
Reexamination Certificate
active
06257673
ABSTRACT:
TECHNICAL FIELD
The present invention relates to percussion tools, or hammer tools, used in connection with lifting equipment, particularly boom mounted hammers. More particularly, the present invention relates to an improved hammer tool with a forward striking mass portion that is larger in diameter and shorter in longitudinal length than prior art percussion tools in order to provide equal or greater striking mass to the work surface, yet reduce risk of stress fractures.
BACKGROUND OF THE INVENTION
Percussion tool bits, or hammers tools, are commonly used in the construction/demolition/quarry industry. Tool bits having various striking faces, for example, blunt, moil, or chisel striking faces, are chosen for a particular application. Blunt tool bits, which have a flat striking face, are particularly useful for breaking up rocks in quarries. Moils or chisels, which have a generally pointed striking face, may be used in quarries to break up a large rock into smaller pieces or for trenching.
These tool bits can be quite large, typically having a shank diameter of 5-8½ inches and a weight of many hundreds of pounds or more. As such, they are generally used in connection with a hydraulic hammer that is boom mounted. These tools are quite costly, often starting at $1000.00 or more.
The prior art hammer tool
2
, as shown in
FIG. 1
, typically includes an elongated cylindrical body
4
having a shank portion
6
at one end of body
4
and a forward portion
8
at the other end of the body
4
. At the distal end
10
of the forward portion
8
is an integral striking face
12
(a blunt face is shown). The shank portion
6
of the hammer tool
2
is received into a chuck housing (not shown) of a power hammer
14
, (which is shown in phantom). Much of the body
4
, including the forward portion
8
and the striking face
12
, extends externally and downwardly of the power hammer
14
, below a lower chuck housing face
16
. In use, the power hammer is raised and lowered over a work surface (not shown) in order to bring the striking face into striking contact with the work surface, typically in a force range from 800-15,000 foot pounds (depending on the hammer class).
As shown in
FIG. 1
, the shank portion
6
and the forward portion
8
have a substantially uniform diameter d
pa
along a longitudinal length L
opa
of the entire tool. Below lower chuck housing face
16
, the diameter of the tool d is uniform along the overall longitudinal length of the forward tool portion L
pa
, which is the longitudinal length of the forward tool portion to the distal end
10
. Thus, the portion of the hammer tool extending below the power hammer has to be of a length relative to the diameter of the tool to impart a sufficient force, determined essentially by the hammer manufacturer and force class.
When new, the tool bit is at its maximum longitudinal length. During use, the longitudinal length slightly decreases. Also during use, the length of the tool bit extending below the hammer can tend to flex during rough handling. Such flexing can generate small stress fractures, of which can lead to ultimate catastrophic failure. Ultimate catastrophic failures often occur within the first 24 hours of use of a new tool bit.
An objective of the present invention is to maintain or increase the life of these expensive tool bits by decreasing the length of the tool that extends below the hammer, yet still provide the same or more striking mass.
DISCLOSURE OF THE INVENTION
The present invention relates to a percussion tool or hammer tool bit including a substantially cylindrical rearward shank portion of a first diameter and substantially uniformly cylindrical forward tool portion, which is axially aligned with the shank portion. The forward tool portion has a diameter that is approximately 15-20% greater than the diameter of the shank portion. The shank portion is of a size and shape to be received into a socket, or chuck housing, of a boom mounted power hammer. The forward tool portion further includes a distally positioned striking face. The forward tool portion extends forwardly of the shank portion of a longitudinal length that, when the tool is received into the socket of the hammer and the striking face makes striking contact with a work surface (such as a pile of rocks in a quarry), the longitudinal length will not flex when the tool is operated by the hammer.
In a preferred embodiment of the present invention, the longitudinal length of the forward tool portion is 35-40% of the overall longitudinal length of the percussion tool bit. According to one embodiment, the striking face is no greater than 28 inches. Thus, the forward tool length is such that the tool will not flex, but the increased diameter of the forward tool portion provides the same or more mass as the prior art with each striking contact.
In another embodiment of the present invention, the tool may further include an integral transition section between the shank portion and the forward tool portion. The transition section includes a proximal end and a distal end such that the proximal end of the transition section is adjacent and integral with the shank portion and includes the same diameter as the shank portion. The distal end of the transition section slopes radially outwardly such that the distal end the sloping section of the transition section is adjacent, integral, and includes the same diameter as the forward tool portion. According to one embodiment, the longitudinal length of the forward tool portion and striking face is no greater than 23 inches with the addition of the transition section.
The hammer tool of the present invention can have various striking faces. In one embodiment, the striking face is a blunt surface. In another embodiment, the striking face is a moil point. In yet another embodiment, the striking face is a chisel.
According to another aspect of the present invention, the percussion tool bit of the present invention is an improvement over the prior art percussion tool bit. The prior art percussion tool bit includes a combined longitudinal rearward shank portion and forward tool portion, where the rearward shank portion and the forward tool portion include a substantially cylindrically uniform and integral diameter. The prior art percussion tool bit's forward tool portion further includes a striking face longitudinally opposite the rearward shank portion. The improvement of the present percussion tool bit includes an increased forward tool portion diameter over the rearward shank diameter in the range of 15-20%, and a decreased combined longitudinal length over the combined percussion tool bit of the prior art of 5-10%. The forward tool portion length of the present invention may be in the range of 35-40% of the overall tool length of the present percussion tool bit. The striking face of the present percussion tool bit may be a blunt, moil, or chisel, as discussed above.
These and other advantages, objects, and features will become apparent from the following best mode description, the accompanying drawings, and the claims, which are all incorporated herein as part of the disclosure of the invention.
REFERENCES:
patent: 2533555 (1950-12-01), Canales
patent: 2629588 (1953-02-01), Neamand
patent: 3027953 (1962-04-01), Coski
patent: 3258295 (1966-06-01), Ives et al.
patent: 3336081 (1967-08-01), Ericsson
patent: 3900058 (1975-08-01), McArdle
patent: 4144868 (1979-03-01), Heitbrink
patent: 5188187 (1993-02-01), Mumper
patent: 5647447 (1997-07-01), Jones
patent: 5884978 (1999-03-01), Bell et al.
patent: 357 980 (1929-03-01), None
patent: 926 614 (1973-05-01), None
patent: 271684 (1914-03-01), None
patent: 1813174 (1993-04-01), None
Annals des mines de Belgique No. 6, p. 596 XP002106257, undated.
Blackburn William D.
Markham David J.
Bagnell David
Petrich Kathleen T.
Ramco Construction Tools Inc.
Singh Sunil
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