Polishing-grindstone mount base assembly

A polishing-grindstone mount base assembly has a mount cassette formed of hard rubber. The mount cassette includes a wedge-shaped rib, having a dove-tail-shape in cross-section for engaging the arm of a conveyor-type plane polisher. The mount cassette is fixed to the mount base with bolts of a synthetic resin which will break on excessive impact, allowing the base for separate from the mount to prevent damage to the base. The base has an abrasive layer on the bottom surface, and protective layers of synthetic resin on each side of the abrasive layer to prevent breaking of the abrasive layer.

INFORMATION DISCLOSURE STATEMENT 
Conventionally, the mount base for a polishing grindstone, which is used 
with a conveyor-type plane polisher for polishing the stones to be used as 
building construction material, comprises a tool in which a metallic base 
has a diamond abrasive grain layer attached on the bottom surface thereof, 
and the base is to be fixed directly to a rigid mount cassette made of 
synthetic resin with metallic bolts. The mount cassette is then to be 
fixed to the arm of a polisher. Because of this construction, it somewhat 
frequently happens that, if the tool touches the corner or other portion 
of the stone while the polisher is rotating, the cassette is destroyed due 
to the shock applied, and the abrasive grain layer attached on the base is 
broken. 
The conventional tool of this type using pulverized diamond as abrasive 
grain is expensive and the tool, once broken, is not reusable. 
SUMMARY OF THE INVENTION 
The present invention relates generally to a polishing-grindstone mount 
base assembly for use with a conveyor-type plane polisher, and is more 
particularly concerned with a polishing-grindstone mount base including 
protective layers, and shear pins for attaching the base to the arm of the 
polisher. 
The present invention has an object to overcome the above-mentioned 
drawbacks of the conventional techniques by providing a 
polishing-grindstone mount base assembly of which a base having an 
abrasive grain layer formed thereon and a mount cassette are separated 
from each other when the tool touches the corner or the like of a stone 
being worked, so that the cassette will not be broken, and also providing 
a polishing-grindstone base having formed thereon an abrasive grain layer 
which will not be broken even with such shock mentioned above. 
According to one aspect of the present invention, a polishing-grindstone 
base is provided, comprising a rectangular base body having formed as 
swollen in the central area of the rectangular bottom surface thereof an 
abrasive grain layer made of a sintered mixture of pulverized diamond and 
abrasive grain and also as circularly swollen on the bottom surface 
thereof on either side of the abrasive grain layer a protective layer made 
of a synthetic resin. 
According to a second aspect of the present invention, a 
polishing-grindstone mount base assembly is provided, comprising a mount 
cassette made of a rigid rubber to be fitted in a fitting recess formed on 
the top of above-mentioned base body, having a wedge-like rib formed on 
the top thereof and a dovetail-like surface along either side and 
longitudinally of the rib, the base body and mount cassette being fixed 
integrally to each other with bolts made of a synthetic resin.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
In the drawings, the reference numeral 1 indicates a rectangular base body 
made of a synthetic resin such as phenolic resin, polyvinyl chloride (PVC) 
or the like, having an abrasive grain layer 2 of a predetermined thickness 
and made of a sintered mixture of abrasive grain and pulverized diamond 
formed as swollen on an abrasive grain layer receiving surface 1a in the 
central area of the bottom thereof, and a resin layer 3 for protection of 
the abrasive grain layer 2, the resin layer 3 being formed as circularly 
swollen on each side 1b of the abrasive grain layer 2. Further, the base 
body 1 has formed on the top thereof a fitting recess 4 in which a 
plurality of screw holes 5 for bolts is formed along the centerline 
thereof. The reference numeral 7 indicates a mount cassette made of rigid 
rubber which is to be fitted into the fitting recess 4 and has formed 
therein screw holes 6 corresponding to the screw holes 5 in the fitting 
recess 4. The rectangular base body 1 and the mount cassette 7 are fixed 
to each other by bolts 8 made of a synthetic resin, the bolts 8 being 
received in the screw holes 5 and 6, thereby forming a 
polishing-grindstone mount base assembly 9. The bolts 8 will be broken 
when more than a predetermined load is applied. 
For assembling the cassette, a dovetail-like rib 10 having a wedge-like 
surface as indicated at 13 along each lateral side thereof is 
longitudinally formed on the top of the mount cassette 7, and a dovetail 
groove 12 having a wedge-like wall at either side thereof is formed in the 
mount arm 11 of the polisher. The dovetail-like rib 10 is inserted into 
the dovetail groove 12 from one end thereof and fixed as force-fitted due 
to the wedge-like surfaces 13 formed longitudinally on the dovetail-like 
rib 10 and the wedge-like walls of the dovetail groove 12. 
Next, the function of the polishing-grindstone mount base assembly 
according to the present invention will be described below. First, by 
inserting the dovetail-like rib 10 formed on the top of the mount cassette 
7 of the polishing-grindstone mount base assembly 9 into the dovetail 
groove 12 formed in the bottom of the mount arm 11 of the polisher from 
the narrow end of the wedge-like surface 13, the mount cassette 7 is 
securely fixed to the mount arm 11 under the action of the wedge-like 
surfaces 13. 
In this condition, a stone (not shown) is polished while the 
polishing-grindstone mount base assembly 9 is being rotated with the 
bottom surface of the mount base assembly 9 being forced against the stone 
surface. 
However, even if a part of the mount base assembly 9 is put in contact with 
a corner or the like of the stone by mistake during polishing, the 
protective resin layer 3 bears against the stone to protect the abrasive 
grain layer 2 from damage. The protective resin layers 3 at opposite sides 
of the abrasive grain layer 2 will be only slightly injured as the case 
may be. Further, when the mount base assembly 9 strongly hits the corner 
or the like of the stone and so is applied with a large load, the bolts 8 
of synthetic resin which join together the lowest base body 1 and the 
mount cassette 7 will be ruptured with a predetermined load, so that the 
base body 1 will be separated from the mount cassette 7. This means that 
the mount cassette fitted in the mount arm will not be damaged, and the 
base body 1, which carries the abrasive grain layer 2, has not been broken 
and can be fixed to the cassette 7 with new bolts 8 for reuse. 
As has been described above, since the polishing-grindstone base according 
to the present invention has a protective resin layer formed as circularly 
swollen on either side of the abrasive grain layer attached in the central 
area of the bottom surface thereof, the abrasive grain layer can be 
prevented from being destroyed when the base body touches a stone or a 
like material being worked by the polishing-grindstone. Also since the 
polishing-grindstone mount base assembly according to the present 
invention is of such a structure that the base body, having an abrasive 
grain layer formed thereon, and the mount cassette, which is to be fitted 
into the mount arm, are joined together with bolts made of a synthetic 
resin which will be ruptured on application of a predetermined load, if 
the polishing grindstone is applied with a larger contact shock than 
necessary when put into contact with a stone to be worked, the fixing 
bolts made of the synthetic resin are ruptured, resulting in separation of 
the base body and mount cassette from each other. Thus, the mount cassette 
can be prevented from being broken. Since the mount cassette is made of a 
rigid rubber, it absorbs the vibration applied during polishing, 
withstands the shock and thus will not be broken. So the mount cassette 
and base body can be reused when joined together with new bolts. 
Furthermore, since the mount cassette is made of the rigid rubber, if made 
in somewhat larger size, it can be securely fitted in the dovetail groove 
in the mount arm. Thus, it can be used for a long term. 
It will of course be understood by those skilled in the art that the 
embodiment of the invention here presented is by way of illustration only, 
and is meant to be in no way restrictive; therefore, numerous changes and 
modification may be made, and the full use of equivalents resorted to, 
without departing from the spirit or scope of the invention as outlined in 
the appended claims.