Stone working – Sawing – Rotary
Reexamination Certificate
2000-06-26
2002-06-25
Eley, Timothy V. (Department: 3723)
Stone working
Sawing
Rotary
C125S022000, C451S547000
Reexamination Certificate
active
06408838
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates in general to a rotary cutting saw which includes a base disk and a plurality of abrasive segments bonded to the outer circumferential surface of the base disk and which is used for cutting, parting or grinding an asphalt, a concrete, a building material or other work material. More particularly, the invention is concerned with such a cutting saw having slits formed in the outer circumferential surface of the base disk and located between the abrasive segments.
2. Discussion of the Related Art
There is known a rotary cutting saw
110
, as shown in
FIG. 6
, consisting principally of a base disk
111
which is made of a tool steel or other metallic material, and a plurality of abrasive segments
112
which are bonded to the outer circumferential surface of the base disk
111
so as to be circumferentially spaced apart from each other at a constant angular interval therebetween. In portions of the outer circumferential surface of the base disk
111
each of which is located between adjacent ones of the abrasive segments
112
, there are formed cutouts or slits
113
each of which extends inwardly in the radial direction of the base disk
111
from the outer circumferential surface of the base disk
111
, and also in the axial direction of the base disk
111
over the entire axial length of the base disk
111
. Each abrasive segment
112
, which is referred to also as a segment chip, consists of a small piece including diamond abrasive grains or other super abrasive grains which are held together with a metal bond or other bonding agent. This rotary cutting saw
110
is a tool which is generally referred also to as a cutting blade, a rotary blade, a cutting grindstone or a grinding wheel, and which is generally used for cutting, parting or grinding an asphalt, a concrete, a building material or other work material, for example.
Each slit
113
is defined by a pair of opposed side surfaces
113
a
,
113
b
and a part-cylindrical surface
113
c
. The side surfaces
113
a
,
113
b
are opposed to each other and parallel to the radial direction of the base disk
111
. The part-cylindrical surface
113
c
defines a part of a cylinder having an axis which is parallel to the axial direction of the base disk
111
and which lies on a center plane between the side surfaces
113
a
,
113
b
. The part-cylindrical surface
113
c
connects radially inner end portions of the respective side surfaces
113
a
,
113
b
. The slits
113
facilitate dissipation or radiation of a heat generated when the abrasive segments
112
are bonded to the base disk
111
, thereby preventing the base disk
111
from being affected by the heat. The slits
113
permit, during a cutting or parting operation with the rotary cutting saw
110
, a cutting fluid to be easily applied to a cutting point at which the work material is cut by the abrasive segments, and also permit cutting chips that are produced at the cutting point to be removed from a groove being currently formed in the work material, thereby improving the cutting or parting performance of the rotary cutting saw
110
.
The rotary cutting saw
110
suffers from a drawback, particularly, when used in successive or repeated operations for cutting or parting the work materials. That is, the cutting chips produced in the cutting operations tend to be concentrated in a “neck” portion of the rotary cutting saw
110
, i.e., a radially outer end portion of the base disk
111
which is radially adjacent to the abrasive segments
112
, whereby the neck portion is worn and thinned due to rubbing thereof against the cutting chips, possibly causing breakage of the abrasive segments
112
.
In view of the above drawback, there has been proposed a rotary cutting saw, as disclosed in JP-Y-56-36967 and JP-Y-01-31422, which includes wear-resistant chips made of a cemented carbide or ceramic material having a high degree of wear resistance. Each wear-resistant chip is bonded to one of the opposed side surfaces of the corresponding slit, in the interest of reducing wear of the neck portion of the rotary cutting saw.
There has been also proposed a rotary cutting saw, as disclosed in JP-A-59-110563 and JP-U-05-5355, which includes wear-resistant chips having respective lengths different from each other, and slits having respective depths or radial lengths different from each other. Each wear-resistant chip, which is made of cemented carbide or ceramic material, is bonded to one of the opposed side surfaces of the corresponding slit whose radial length corresponds to the length of the wear-resistant chip. This construction prevents flows of the cutting chips along a single circle having a given radius, namely, prevents the cutting chips from being concentrated at a single radial portion of the base disk, and facilitates the cutting chips to be dispersed so as to be distributed into a plurality of radial portions of the base disk, e.g., a plurality of mutually concentric circles having different radii, so that amount of wear of the neck portion of the rotary cutting saw is reduced.
However, in each of the above-described conventional rotary cutting saw in which the wear-resistant chip is bonded to one of the opposed side surfaces of each slit, a plurality of small turbulent or eddy flows of the cutting chips are generated in each slit during a cutting operation, due to the presence of a stepped or protruding portion in the inner surface of the slit, thereby impeding entrance of the cutting chips into the slits and accordingly causing the cutting chips to stay in the groove being currently formed in the work material. A portion of the base disk which portion is adjacent to the wear-resistant chip, i.e., the neck portion of the rotary cutting saw is still likely to be somewhat worn by the cutting chips staying in the currently formed groove of the work material. That is, the wear in the neck portion is not satisfactorily prevented even in the above-described known cutting saw. Further, the wear-resistant chip bonded to one of the side surfaces of the slit inevitably reduces a spacing between the side surfaces. The reduced spacing between the side surfaces of the slit causes a reduced efficiency of discharge of the cutting chips from the currently formed groove and a reduced efficiency of application of the cutting fluid to the cutting point, thereby resulting in a reduced cutting efficiency or a reduced durability of the cutting saw.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a rotary cutting saw constructed to reduce an amount of wear of its neck portion without deteriorating its cutting performance.
Various studies conducted by the present inventors under the above-described situation revealed that the wear of the neck portion of the cutting saw is reduced by suitably designing the shape of each slit formed in the outer circumferential surface of the base disk of the cutting saw. For example, the inventors found a fact that the wear of the neck portion is advantageously reduced where the opposed side surfaces of the slit are connected at their respective radially inner end portions to the part-cylindrical surface which has an inside diameter larger than a circumferential distance between the radially inner end portions of the opposed side surfaces, such that one of the side surfaces is smoothly connected to the part-cylindrical surface without a stepped or protruding portion therebetween.
It is assumed that, in a cutting operation with the conventional cutting saw, a plurality of small eddy flows of the produced cutting chips with a cutting (cooling) fluid are generated within each slit, and the time for which the cutting chips stay in the slit is generally reduced due to turbulent flows occurring as a result of mutual collisions of the small eddy flows. That is, the turbulent flows tend to undesirably cause movements of the cutting chips out of each slit, so that most of the cutting chips are likely to be discharged from each slit, before a certain amou
Makihara Hitoshi
Ogata Seiya
Eley Timothy V.
Noritake Diamond Industries Co., Ltd.
Oliff & Berridg,e PLC
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