Stone working – Sawing – Rotary
Reexamination Certificate
2002-07-23
2003-09-09
Rose, Robert A. (Department: 3723)
Stone working
Sawing
Rotary
C451S542000
Reexamination Certificate
active
06615816
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates in general to a rotary cutting saw which is used for cutting, parting or grinding a stone, a concrete, an asphalt, a brick, a ceramic or other hard work material.
2. Discussion of the Related Art
There is known a rotary cutting saw
30
, as illustrated in
FIG. 3
, consisting principally of a base disk
31
and a plurality of abrasive segments
32
which are fixed to an outer circumferential surface of the base disk
31
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
31
each of which is located between adjacent ones of the abrasive segments
32
, there are formed cutouts or slits
33
each of which extends inwardly in the radial direction of the base disk
31
from the outer circumferential surface of the base disk
31
. Each abrasive segment
32
, which is referred to also as a segment chip, consists of a small piece including diamond abrasive grains or other abrasive grains which are held together with a metal bond or other bonding agent. This rotary cutting saw
30
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 or parting a stone, a concrete, an asphalt, a brick, a ceramic or other hard work material.
During a parting or cutting operation with the rotary cutting saw
30
, the rotary cutting saw
30
is rotated and is moved relative to a work material in a cutting direction that is perpendicular to an axis of the cutting saw
30
. The slits
33
facilitate evacuation of cutting chips (that are produced at the cutting point) from a slot being currently formed in the work material, thereby making it possible to improve the cutting or parting performance of the rotary cutting saw
30
. In this instance, a relatively large amount of load is applied to each of axially opposite end portions of the abrasive segment
32
(which portions constitute portions of respective axially opposite end surfaces of the cutting saw
30
) in a direction opposite to the cutting direction, while a relatively small amount of load is applied to an axially intermediate portion of the abrasive segment
32
in the direction opposite to the cutting direction. Therefore, each of the axially opposite end portions of the abrasive segment
32
tends to be worn in a larger amount, than the axially intermediate portion of the abrasive segment
32
.
In view of such a drawback, there have been proposed various rotary cutting saws or grinding wheels, as disclosed in JP-Y2-S53-13991 (publication of examined Japanese Utility Model Application laid open in 1978), JP-U-S47-6491(publication of unexamined Japanese Utility Model Application laid open in 1972), JP-A-S57-83372 (publication of unexamined Japanese Patent Application laid open in 1982) and JP-Y2-S60-12694 (publication of examined Japanese Utility Model Application laid open in 1985), in the interest of minimizing a local wear of the working or grinding surface of the cutting saw or grinding wheel.
Specifically described, JP-Y2-S53-13991 discloses a grinding wheel which includes an abrasive layer bonded to an outer circumferential surface of a base disk. The abrasive layer of this grinding wheel consists of an intermediate portion and opposite end portions located on respective opposite sides of the intermediate portion as viewed in an axial direction of the grinding wheel, wherein each of the axially opposite end portions has a higher degree of density of abrasive grains than the axially intermediate portion. JP-U-S47-6491 discloses a grinding wheel in which the abrasive layer consists of an axially intermediate portion and axially opposite end portions, wherein each of the axially opposite end portions has a higher degree of bonding strength for bonding the abrasive grains than the axially intermediate portion. JP-A-S57-83372 discloses a rotary cutting saw having a plurality of abrasive segments each consisting of main grinding layers and auxiliary grinding layers which are alternately arranged as viewed in an axial direction, wherein opposite end portions of each abrasive segment are provided by the main grinding layers. Each of the main grinding layers has a higher degree of density of abrasive grains than each of the auxiliary grinding layers. JP-Y2-S60-12694 discloses a rotary cutting saw having a plurality of abrasive segments each consisting of a body portion and cylindrical portions which are embedded in the body portion. Each of the cylindrical portions has a lower degree of density of abrasive grains than the body portion, or alternatively, the abrasive grains or bonding agent of each cylindrical portion has a lower degree of hardness than that of the body portion.
However, in each of the above-described cutting saws or grinding wheels in which the abrasive layer or segment is constituted by a plurality of portions different from each other in characteristics or properties, the abrasive layer or segment in its entirety is easily worn, making it impossible to satisfactorily reduce amount of wear in the axially opposite end portions of the abrasive layer or segment. In view of such a drawback of the conventional cutting saws or grinding wheels, the present applicant invented a rotary cutting saw including a base disk and a plurality of abrasive segments which are fixed to an outer circumferential surface of the base disk, wherein each abrasive segment has a larger thickness than the base disk so that each of opposite end portions of each abrasive segment is projects from the corresponding side surface of the base disk outwardly as viewed in an axial direction of the base disk. Each of the opposite end portions of the abrasive segment includes not only abrasive grains but also wear-resistant grains having substantially the same size of the abrasive grains, such that each of opposite side surfaces of the abrasive segment is provided by a wear-resistant surface on which the wear-resistant grains as well as the abrasive grains dispersively exposed. This rotary cutting saw is disclosed in JP-B2-H7-12592 (publication of examined Japanese Patent Application laid open in 1995). This rotary cutting saw is capable of maintaining a flatness or uniformity of the working surface of each abrasive segment more satisfactorily than the above-described conventional tools, and reducing amount of wear in the axially opposite end portions of each abrasive segment.
However, even this rotary cutting saw disclosed in JP-B2-H7-12592 has a technical problem to be solved. In this rotary cutting saw, a ratio of a sum of cross sectional areas of the wear-resistant grains exposed on the side surface of each abrasive segment with respect to an area of the entirety of the side surface is 3-20%. Since the wear-resistant grains are dispersed or distributed at random on the side surface, a spacing distance between each adjacent pair of the wear-resistant grains is not constant. As a result, a sufficient degree of wear resistance can not be obtained, particularly, in local portions of the side surface in which a density of the wear-resistant grains is relatively low. Further, a recess or groove is likely to be formed in each of such local portions as a result of their wear. The formation of the groove impedes flows of cutting (cooling) fluid or cutting chips, thereby making it difficult to distribute the cutting fluid evenly over the entirety of the side surface of each abrasive segment, and making it difficult to satisfactorily improve the cutting performance and prolong the service life.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a rotary cutting saw having abrasive segments each of which has, in its opposite side surfaces, wear-resistant surfaces in which wear-resistant grains are distributed in an improved manner, for thereby effectively reducing amount of wear of each wear-resistant side surface while maintaining an
Noritake Co., Limited
Oliff & Berridge PLC.
Rose Robert A.
LandOfFree
Rotary cutting saw having abrasive segments in which... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Rotary cutting saw having abrasive segments in which..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Rotary cutting saw having abrasive segments in which... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3025449