Note: Descriptions are shown in the official language in which they were submitted.
~:~ 2, ~
Docket BV-2399
PULPSTONE
DAN D. BACIC
32 Goldcrest Drive
Stoney Creek, Ontario L8G 4T9
Canada
TECHNICAL FIELD
This invention relates to an improved pulpstone
or grinding wheel having an abrasive periphery that is
filled with a concrete core and the method of making the
5 pulpstone. More particularly it is concerned with a novel
structure for holding the abrasive segments of a pulpstone
together whereupon they are then used as a form for molding
the concrete core that is poured into the assembled annulus
of segments for completing the attachment of the segments
10 to the periphery of the core.
Background and Information Disclosure Statement
The following U.S. Patents arP representative of
the most relevant prior art known to the applicant at the
time of the filing of this application.
U.S. Patents
933,603 Wagg September 7, 1909
2,369,639 Ball et al. February 20, 1945
2,453,748 Fisher et al, November 16, 1948
2,887,276 Minarik May 19, 1959
4,351,486 Schmoller et al. ~eptember 28, 1982
The conventional pulpstone is usually made by
assembling a plurality of abrasive segments that are then
filled with a concrete core whereby to form an abrasive
periphery integral with a central core made of concrete, or
25 in some instances it has been proposed to assemble such
segments on the periphery of another form of a rigid body
like a cylindrical metal annulus. The segments are
frequently provided with integral studs extending radially
inwardly toward the center of the pulpstone, which segments
30 are assemblecl together with a concrete core by means of
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these studs being bolted to the reinforcing cage of the
concrete core, the studs subsequently becoming permanently
bonded and sealed within the center core.
The patent to Fisher et al. is of general
5 interest only in showing an abrasive grinding wheel for the
surface finishing of glass plates wherein the grinding
wheel means is constructed with abrasive segments bolted to
a circular supportin~ ring means. The grinding wheel of
this disclosure utilizes the exposed ends of the segments
10 for grinding the glass sheet being polished as
distinguished from the periphery of the wheel as with a
pulpstone used for grinding logs to make a wood pulp. As
the segments of the glass plate grinding means wear down,
the successive rings that support the segments may be
15 removed to provide a continuing support for the remaining
portions of the abrasive segments forming the wheel.
The remaining patents cited above all show
grinding wheels for usP in making wood pulp. Wagg and
~inarik each show a bolting arrangement for attaching a
20 plurality of abrasive elements to a centrally disposed
metal cylinder or ring. The Wagg patent teaches the use of
a molten filler flowed into place between the segments and
the mounting means therefore to preclude any movement of
the segments relative to it's metal support ring when the
25 wheel is in use. The Minarik disclosure uses an eye-bolt
with each segment, the eye-bolt being carried on a crossrod
that passes through the center of each of the indi~idual
segments of a pulpstone to fasten the individual segments
to the surface of a cylindrical cast iron drum. In this
30 construction the individual segments are mounted on the
drum with spaces between all sides of the individual
segments to make passages available for the circulation of
a fluid from the cylinder through the spaces to the
grinding surface of the stone to assist in the grinding
35 process.
Ball et al. provides a wheel wherein a unitary
solid annulus constitutes the grinding element of a
pulpstone, as distinguished from a pulpstone fabricated
2~2~2~2
with a plurality of individual segments assembled together
on the periphery of the grinding stone to form the grinding
surface of the pulpstone structure. This Ball et al.
disclosure provides for the attachment of the annulus to a
5 metal ring positioned concentrically within the annulus and
threaded spokes that have one end integrally attached to
the respective side walls of the annulus that are used to
tension the annulus around the metal ring to prestress the
abrasive ring against the stresses produced by the grinding
10 process. The central opening in the Ball et al. annulus is
filled with concrete after the annulus has been mounted on
the metal ring and the nuts 11 by which the tension in each
of the respective spokes is adjusted then become
permanently sealed within the concrete core.
Schmoller et al. disclose several systems for
mounting abrasive segments on the periphery of pulpstones.
In Figs. 1-~ a very general disclosure sets forth a bolting
arrangement for supporting such segments on a concrete core
and in Figs. 6-11 the segments are shown mounted on a steel
20 ring or cylinder. In each instance the segments are each
provided with nut means situated within the segments that
are simply threaded onto bolts extending outwardly from a
support cylinder to hold the several segments onto their
support means, there being no detailed discussion of the
25 particulars of the bolting system except as the bolt
structures are modified to promote the circulation of water
to the surface of th~ pulpstones through the segments which
are made somewhat porous or are spaced apart to permit the
water to flow outwardly to the surface of the pulpstone.
30 Brief Description of This Invention
- An improved bolting arrangement and method of
completing the assembly of a pulpstone is shown herein for
mounting a plurality of abrasive segments on the periphery
of a pulpstone. The invention is concerned with the
35 mounting of the individual segments on the concrete core of
an otherwise conventional type of such pulpstones and makes
use of the internal reinforcing means of the core for
supporting the segments.
2 ~ ~
In the practice of this invention, the plurality
of segments that are to be carried on the periphery o* the
stone, are f~rmed into an annular or a circular assembly of
the segments that resembles a "chimney". This chimney is
5 constructed by first using a number of appropriately shaped
abrasive segments to form a ring or circular assembly and
then another circular assembly of the segments is built up
on the first ring and so forth to finally assemble all of
the segments into the cylindrical chimney of a desired
10 height. Then certain of the reinforcing rings for the
concrete core that is to be subsequently poured into the
chimney and cured to form the support core for the
segments, are fitted concentrically within the chimney.
Each one of the several segments in the chimney
15 are provided with a plurality of bolt holes extending from
their grinding surfaces radially inwardly to receive bolt
means. Suitable seating means are provided in each hole
and either the head of the bolt or the nut means for the
bolt is engaged on the seat with a somewhat plastic or
20 deformable washer fitted between the seat and the engaged
element. The shank of the bolt extends radially inwardly
so that the inner end of the bolt can be supported from the
reinforcing rings.
After the chimney has been built and the bolt and
25 nut means have been assembled together with the reinforcing
rings and drawn up to the proper tension, the remaining
reinforcing structure is built up within the center of the
chimney and the concrete is poured into the mold thus
formed. When the concrete is cured the wheel structure may
30 be finished.
The preliminary molding of the green segments
with the holes for the bolts for securing the segments to
the reinforcing rings makes it possible to improvs the
firing process for the initial fabrication of the segments
35 themselves. The production of a finished segment with
such bolt holes also simplifies the assembly process for
completing the wheel structure. Since the green molded
segments are processed with a plurality of bolt holes
2 ~ ~ 3 .d ~ 2~
extending entirely through the mass of the segment, when
the abrasive grains and the bond mixture for the segments
is fired to produce the ultimate abrasive segment, the burn
can be completed in a shorter time and with the expectation
5 that a better quality of product will result since the heat
to cure the segment can blow more rapidly and evenly
throughout the mass being fired. As will be made more
fully evident from the discussion below, these fired
segments can be more easily and quickly assembled together
10 with the reinforcing rings of the core means as compared
with the procedure heretofore required to complete the
assembly of conventional pulpstones and with a saving in
time needed for the production of the known product.
In the Drawings
Figure 1 is a vertical sectional view partly
broken away,-~showing one of the several bolt means and
reinforcing ring assemblies used for mounting an abrasive
segment on the periphery of a pulpstone, included in the
showing is the broken away segment mounted on a cured
20 concrete core;
Figure 2 is a detailed vertical side view taken
at 90 with re ~ ct to the view in Fig. 1 showing a side
view of the nut means for cooperating with the bolt as
shown in Fig. l; and
Figure 3 is a vertical sectional view like Fig. 1
showing an alternate form of bolt and nut arrangement.
Description of the Preferred Embodiments
The present invention is concerned with the
mounting of a plurality of abrasivs segments on the
30 periphery of the more popular types of pulpstones having a
concrete core generally similar to the structurPs shown in
the above mentioned patents to Minarik and Schmoller et
al., Figs. 1-5. Such plupstones are cylindrical in shape
and may have a diameter falling within a range of from 50"
35 to 75" or more and a length of from 27" to 90" or more.
The present invention makes use of a poured center core of
reinforced concrete and the abrasive blocks are supported
in part from certain of the reinforcing rings centered in
,
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the core to hold the segments on the periphery of the core
to produce a pulpstone adapted to be rotatably driven in
the known type of pulp grinding machine to convert logs
into a pulp for the manufacture of paper products and the
5 like.
The abrasive segments can be of any known shape
having side edges that can be interfitted to completely
cover the peripheral surface and usually the edges of the
individual segments are angularly related to produce the
10 best grinding relationship between the ultimate abrasive
surface of the pulpstone and the wood being ground. The
preferred segments used on this pulpstone are roughly 7" by
12" and are about 5" thick. None of these dimensions,
however, are critical.
The segments used in this invention are formed of
a known abrasive mix and ceramic bond that is first molded
in the usual manner. The specified mix is pressed into the
proper shape and is provided with a plurality of holes for
the bolts as will be explained more fully below, said holes
20 extending radially inwardly from the grinding face of the
segment. The molded segment having a plurality of holes
therein extending through the body of the segment is then
fired and because the plurality of holes extend entirely
through the body it may be fired in the conventional
25 process and the heat will be distri~uted more rapidly and
evenly throughout the body of the mass being fired. This
makes for a more uniform and faster firing process.
Referring to the drawings, a segment 10 that is
shown partly broken away is provided, which segment
30 preferably has two or more spaced apart holes to receive
bolts as will appear more fully below, one of which holes
is shown in Fig. 1. The hole is perpendicular to the
grinding surface 12 and is disposed to extend radially
inwardly from that surface. The hole has an upper section
35 with a larger diameter 14 at its top end referring to Fig.
1 that is provided for the purpose of receiving the head 16
of a bolt that has a shank portion 18 that fits neatly into
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the lower section 20 of the hole, which section has a
smaller diameter than the upper section 14.
These segments are made to have the conventional
shapes whereby to be assembled in the usual pattern in a
5 chimney for making a pulpstone and thus a plurality of
these segments may be fitted together by forming a ring of
the end segments in a fixture for holding the segments in a
precise position and spaced apart with a conventional
rubber-cork gasket or similar compressible material between
10 all the adjacent sides of the abutting segments. When the
first ring has been assembled, a second ring of segments is
laid precisely on top of the completed ring and the gasket
material is put in place between all of the abutting side
faces of the segments in that ring. Succeeding rings are
15 similarly precisely aligned with the other segments with
the usual gaskets between the segments until the desired
pulpstone wheel length has been assembled. This precision
assembly of segments may then be fired or baked or
otherwise treated to cure the gasket material, to complete
20 the chimney that is then ready for further processing.
When the chimney-like assembly has been baked or
otherwise solidified, the outer reinforcing rings for the
concrete center that is to be subsequently poured into the
center of the chimney, are assembled within the annulus
25 formed by the segments. The outer cage of these
reinforcing rings is supported on suitable straps, fixtures
or other known means (not shown), two of which rings 24 and
26 are shown spaced on the opposite sides of the nut means
and the bolt hole shown in Fig. 1. These rings are held
30 concentrically spaced within the annulus of the assembly of
segments and the reinforcing rings are positioned to
cooperate with the bolts that are fitted into the plurality
of holes in each of thP segments. For this reason the
reinforcing rings in the outer cage of the reinforcing
35 rings are mounted on their supporting means in closely
spaced pairs such as 24 and 26, with the two rings of each
of the respective pairs spaced closely to but on the
2~3.~
opposite sides of each of the vertical center lines that
extend through the centers of all of the holes 14-20.
The view shown in Fig. 1 shows a detailed view of
a bro~en away portion of a segment that is shown in its
5 assembled relationship on the periphery of the concrete
center core that has been poured and cured within the
annulus of abrasive segments. But before the concrete is
poured, and after the rings forming the outer cage of the
reinforcing have been set in position, the several bolts 1
10 can be inserted in their respective holes in each of the
segments from the outside of the annulus with a rigid
washer 30 and a deformable or compressible washer 32 under
the head of the bolt. Each bolt is pushed through the
several sections 14 and 20 of their respective holes so
15 that the inner end of the bolt may be screwed into a
cooperating nut means 34. The nut means shown in ~ig. 1
is a custom made shape having a central threaded body
portion to coact with the threaded bolt means and the body
of the nut means each of which has a pair of oppositely
20 facing saddle shaped wings 36 an 38. The wing 36 fits
under and is adapted to enga~e the under side of ring 24
when the bolt is tightened and the wing 3~ cooperates with
the ring 26 in a similar manner. The bolt shown in Fig. 1
is a cap screw type and may be hand tightened with an Allen
25 wrench that fits into the head of the bolt.
When all of the segments and their respective
bolt and nut means have thus been preliminarily assembled
together with the outer cage members 24 and 26 of the
reinforcing, the bolts can all be carefully torque
30 tightened to the same tension, preferably about 35 foot
pounds to produce a tensile stress of 3000 pounds in each
bolt. The remaining more centrally disposed reinforcing
elements can then be placed in their normal positions and
the wet concrete to complete the basic pulpstone structure
35 can then be poured and cured, whereupon the pulpstone is
ready for finishing and ultimate use in a pulp grinding
machine.
2 ~
Figs. 1 and 2 show a custom made nut means for
mounting thé several segme*ts on the reinforcing rings 24
and 26 but Fig. 3 shows a simpler assembly of bolt means,
washers, and conventional nut means. In this disclosure, a
5 standard bolt having a hex head 40 is shown. The bolt
engages a washer 42 that seats under the rings 24 and 26 of
the outer reinforcing cage. A nut means 44 cooperates with
this bolt, there being a washer 46 and a compressible or
deformable washer 48 between the nut and the seat in the
10 hole.
When either the nut and bolt means of Figs. 1 and
2 or the means shown in Fig. 3 is used, a much simpler
method of manufacturing a pulpstone is shown as compared
with the assembly procedure used heretofore. The herein
15 disclosed bolting system utilized most of the standard
techniques but simplifies the assembly operations by
eliminating the necessity for preassembly of bolting ~tuds
in the threaded holes molded in the bottom sides of the
conventionally used segments and the fixtures required for
20 the precision mounting of the studs in the segments, as
well as the curing of the cement used for bonding the
threaded ends of the studs in the threaded holes of the
segments and the necessity for the manufacture of the
custom made stud structures themselves. Not only are these
25 savings in the manufacturing procedures realized but there
is a saving in the manufacturing e~uipment needed, and the
custom manufacture of the studs. Furthermore, the herein
disclosed mounting means for the abrasive segments makes it
possible to correct the torque specifications in the wheel
30 on each segment after the concrete is cured, to assure the
correct compression stressing of the segments before the
pulpstone is put into use and even after it has been in
use. It is to be especially noted, that because the
threaded engagement of the studs in the molded threads of
35 the holes in the bottoms of the segments as used here-to-
fore has been entirely eliminated, a stronger attachment of
the segments of this invention to the core is achieved.
Also cracked or broken segments can be more easily replaced
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than is possible in pulpstones with concrete cores used
today.
This method of building a pulpstone permits
compression forces to be built up in the chimney structure
5 or core assembly by the torquing of the bolts before the
concrete is poured whereby a more precise adjustment of the
stresses in the rim of the wheel can be made. As mentioned
above, the proper prestressing of all of the abrasive
segments can be assured from time to time while the
10 pulpstone is in use.
While the above describes the preferred form of
this invention it is suggested that modifications thereof
may occur to those skilled in the art that will fall within
the scope of the following claims.
