Title of Invention	A METHOD OF MANUFACTURING GRINDING ROLLER FOR RAYMOND TYPE PULVERIZERS AND GRINDING ROLLER FORMED THEREOF WITH GRINDING BITS
Abstract	This invention relates to a method of manufacturing grinding roller for coal pulverizing in Raymond type pulverizers with replaceable grinding bits, grinding roller formed thereof and grinding bits comprising the steps of forming grinding bits (05) of high wear resistant material fitted onto a base material of low carbon steel/cast iron, drilling holes (06) on the soft portion of the bits, forming inner base (01) of the roller by casting or by fabricating of plate and machined both on the outside and inside and provided with tapped holes (02) at both sides, the inside surface of the bits having contour in matching relationship with the outside surface of the base (01), being assembled by connecting 2 to 3 rows of bits by stud rods (09) through tapped holes (02) of the base, the complete roll is formed by assembling the said rows of grinding bits (05) on the base roll (01) by fastening the rows of bits to the base roll with the help of clamping plates (11), screws (08) and nut (10).

Title of Invention

A METHOD OF MANUFACTURING GRINDING ROLLER FOR RAYMOND TYPE PULVERIZERS AND GRINDING ROLLER FORMED THEREOF WITH GRINDING BITS

Abstract

This invention relates to a method of manufacturing grinding roller for coal pulverizing in Raymond type pulverizers with replaceable grinding bits, grinding roller formed thereof and grinding bits comprising the steps of forming grinding bits (05) of high wear resistant material fitted onto a base material of low carbon steel/cast iron, drilling holes (06) on the soft portion of the bits, forming inner base (01) of the roller by casting or by fabricating of plate and machined both on the outside and inside and provided with tapped holes (02) at both sides, the inside surface of the bits having contour in matching relationship with the outside surface of the base (01), being assembled by connecting 2 to 3 rows of bits by stud rods (09) through tapped holes (02) of the base, the complete roll is formed by assembling the said rows of grinding bits (05) on the base roll (01) by fastening the rows of bits to the base roll with the help of clamping plates (11), screws (08) and nut (10).

Full Text	-2- FIELD OF THE INVENTION: The present invention relates to a method of manufacturing grinding rollers for Raymond type pulverizers and grinding roller formed thereof with grinding bits. More particularly the present invention relates to the methods of manufacture and replacement of grinding roller of frustum-conical shape used to grind coal in vertical spindle mills of Raymond design, BACKGROUND OF THE INVENTIN WITH PRIOR ART DIFFICULTES: In bowl mill raw coal is fed through center feed pipe. Coal falls at the center of the rotating bowl. Bowl is lined with replaceable hard liners called bull ring segments. Due to centrifugal force, the coal starts moving towards the bowl periphery in a spiraling fashion. In the existing process the bowl mill is adopted in such a manner that coal comes between the grinding roll and bull ring segments and gets crushed. The crushed coal is then carried by the hot air under pressure to the classifier section for further transportation to the boiler for firing. For imparting the grinding pressure required, spring assembly is provided which presses down the grinding roll on to the bull ring segments. There are three rolls kept 120 degrees apart. Similarly there are 3 spring assemblies to press them down. There is provision -3- in these mills to adjust the gap between grinding roller and bull ring segments by moving the grinding roller down and forward. Due to abrasive nature of the coal, both grinding rollers and bull ring segments get worn out and gap between them widens. Approximate life ranges of the bowl mill is from 2000-4000 hours depending on the material of the wearing elements and abrasiveness of the coal. Grinding rollers and bull ring segments are replaced periodically. Grinding rollers for Vertical Pulverizing mills are generally made from White cast iron outer layer and a soft core of grey/nodular iron. In this process, which is centrifugal casting, first the white cast iron is poured at temperature of around 1280 Deg C and immediately after that grey/nodular iron is poured to form a metallurgical bond. White cast iron is very hard, which gives wear resistant properties. Ductile cast iron/nodular iron gives toughness to withstand the impact and it is easy to machine to match the outside diameter of the housing. However, rollers made from this method result in a distinct collar (hump) formation at bigger or smaller or on both ends during the operation of these rollers. This means that only the center part wears leaving the edges without much wear. This prevents proper adjustment of gap between the grinding roller and bullring segments, resulting in improper grinding. In vertical spindle mills of Raymond type there is provision to adjust the gap between the grinding roll and bullring segments by lowering -4- or raising the grinding roller. But the pattern of the wear is such that uniform gap cannot be maintained, In the conventional roller replacement process, 3 Journal Opening Cover (door) which give access to the rollers are opened and entire Journal assembly is taken out and the grinding roller is replaced, which process is much time consuming. Another disadvantage of the prior art is that with the passage of time due to wear action of the coal, the outer surface of the roller becomes smooth. This leads to slippage of the roller and leads to the fall in the grinding efficiency. Another disadvantage of the rollers made from the conventional casting process (either centrifugally cast or static cast), is that the entire set of 3 rollers is replaced with a new set. The worn out, which is thrown, roller weighs approximately between 500 Kilograms to 1200 Kilograms, depending upon the size, of cast/nodular iron with some amount of nickel or high chrome material stili in it. This leads to great wastage of natural resources. The present invention has proposed to remove the difficulties of the aforesaid prior art disadvantages. -5- DESCRIPTION OF THE INVENTION: One object of the Invention is to propose a method of manufacture of grinding roiis through mechanically fastened grinding bite, replacing worn out bits and making the roller new and efficient again. Another object of the invention is to provide grinding bits arrangement such that there is soft metal portion between the two bits, which soft metal portion gets worn out faster than the very hard grinding bits, to enable the grinding bits project out with gap between them so that these projecting bits act like gear teeth and bite Into and plough in the coal thus vastly improving the grinding process. An yet another object of the invention is to provide removable mechanical fastening means for fixing of bits of high wear resistant material on the top surface of the base roller with clamping plates, screws or by welding. With the rollers made form the grinding bits, the entire roller can be used as It is, after replacing the worn out bits with new bits. Replacement of the conventional rollers takes about 2 to 3 shifts with 3 to 4 men working. This entails removal of the Journal Opening Covers, removal of roller assemblies or tilt out roller assemblies. -6- This method of replacement entails handling of heavy paits with cranes, hoists etc. Replacement of grinding bits according to the invention would take a fraction of that time of conventional grinding roll for replacement, thus vastly improving the availability of mills for power generation. The present invention has developed grinding rollers and method of producing the grinding rollers for Raymond type pulverizers in a new approach by forming grinding bits of high wear resistant: material of sintered earbide or high chrome or equivalent material, with formed holes In the bits to fix fastening means, forming the base of the roller through casting or fabrication of plate, tapped holes at both sides of the rollers, providing clearance/tapped holes in the bits and maintaining inside surface of the bits having contour in matching relationship with the conical face of the base, connecting 2 or 3 rows of bits through stud rods and fastening to the base roller through clamp plates and screw arrangement through the formed holes in the grinding bits. The grinding bits produced according to the invention have soft metal portions on the outside face of their periphery and have hard metal portions at the center. The proposed invention will be better understood from the following description with reference to the accompanying drawings in which -16- means comprising of clamping plates (11), screws (08) and nut (10) to constitute the completed roll and thus securing easy and faster replacement of worn out grinding bit/s only on releasing the fastening means. 9. The grinding bits of high wear resistant material as formed according to method of claim 1 to constitute a grinding roller for coal pulverizing. Dated this 15th day of May 2007 (P.D.GUPTA) OF L.S. DAVAR&CO. Applicant's Agents -7- Figure 1 and 2 show in perspective view base roller with tapped holes at both sides of the roller, according to the invention. Figures 3 &4 show perspective view of both sides of the roll showing machined top surface of the base roll, according to the invention. Figure 5 shows a perspective view of a grinding bit with holes according to the invention. Figure 6 shows another perspective view of a grinding bit according to the invention. Figure 7 shows yet another perspective view of a grind bit according to the invention. Figure 8 shows further perspective view or a grinding bit covering the entire length of a base roll according to the invention. Figure 9 shows in perspective view a completed assembled roller on the base roll with 3 rows of grinding bits according to the invention. Figure 10 shows another perspective view showing form other end of the complete assembled roll according to the invention. Figure 11 shows in perspective two rows of assembled grinding bits over the base roll according to the invention. -8- Figure 12 shows in perspective taken from another end the two rows of bits assembled over the base roll. Figure 13 shows a perspective view of completely assembled roll with 2 rows of bits according to the invention. Figure 14 shows another perspective view taken from another side of the roll showing two rows of assembled grinding bits. Figure 15 shows a plan view of a base roll with dovetailed slots. Figure 16 shows a plan view representing the grinding bit to be engaged in dovetailed sbts of a base roil according to the invention. Figure 17 shows schematically the pattern of wear of the conventional grinding roller made from centrifugally cast white cast iron material. Figure 18 show haif cross sectional view of the complete assembled roll with grinding bits and base roll according to the invention. In conventional grinding roller the wear pattern of roller made from centrifugally cast white cast iron material is shown in Figure 17. The figure 17 shows the center part of the roller wears leaving the edges without much wear. This uneven wear of the roller leads to fall in throughput and fall in the quality (finesses required) of output. This -9- defect leads to coal reject through reject spout, thus wasting the precious coal. The present Invention has developed a roller wherein the grinding bits of a roller are made of high wear resistant material like sintered carbide or high chrome or other high wear resisting material. The said grinding bits are shown in figurers 5 to 8 wherein the grinding bits as one row is shown by reference numeral (05) having clamp plate (11). These bits are then connected metallurgically to base material of low carbon steel/cast Iron. Holes (06) are drilled on the soft portion of the bits (05). Figures 1 and 2 show the inner base (01) of the roller produced through either a casting process made of nodular iron or fabrication through weldabie mild steel plates. The said base of the roller is then machined both on the outside and inside to have conical surface. The said base roll (01) has tapped hole (02) at both sides through which the grinding bits (05) are fastened with base roll by clamping plate (11) and screws (08), grinding bits (5) have clearance/tapped holes (06) in them, as shown in figures 5# 6, 7 & 8. Inside surface of the said bits have contour in register relationship to match with the conical face of the base. 2 rows or 3 rows of bits are connected through stud rods (09) and with the help of clamping plate (11), nut (09) and screws (08) are fastened to the base roller (01). This fastening means is shown in figure 18. The complete assembled rolls with 3 rows and 2 rows are shown in figures 9 to 14. -10- In another embodiment of the grinding roller manufacture: 1. The bits (05) are made of high wear resistant like sintered carbide or high chrome or some such material. There are holes (06) in these bits for fixing. (Figures 5,6, 7,8) 2. The base (01) of the roller is then manufactured through either a casting process or fabrication through plate method. 3. Then the top surface of the base is machined to obtain a 8, 10, 12 or more number of flat faces. (Figure 3 &4) 4. Base roller has got tapped holes (02) on both sides. (Figure 2) 5. Bits have got clearance/tapped holes (06) in them. (Ref. Figures 5, 6, 7 & 8). Inside surface of the bits is flat to match with the base and outside surface is conical. 6. 2 rows or 3 rows of bits (05) are connected through stud rods (09) and these are in turn fastened to the base roller through clamp plates (11) and screws (08) arrangement. -11- In another embodiment of manufacture of grinding roller; 1. The bits (05) are made of high wear resistant material like sintered carbide or high chrome or some such material. Bits are then shrunk fitted onto the carbon steel bit. 2. Inner base (01) of the roller is then manufactured through either a casting process or fabrication through plate method. 3. Then the top surface of the inner base is machined to obtain a 8, 10, 12 or more number of flat faces 04 (Figure 3) or it is conical. 4. There are holes (06) in the carbon steel portion of the bits for fixing (Figures 5, 6, 7, 8). Inside profile of the bits matches with the outside profile of the base. 5. 2 rows or 3 rows of bits are connected through stud rods (09) and these are in turn fastened to the base roller through clamp plates (11) and screws arrangement (08). -12- In another embodiment of method of manufacture of grinding roller: 1. Dovetailed slots (12) are milled on the base roller (01). (fig.15). The top surface of which could be conical or having 8 to 10 flats surfaces. 2. Bits (07) (fig. 16) are pushed in these dovetailed slots. 3. These bits are fixed through clamp plates (11) from sides, which are fixed with screw (08) to the inner base roll (01). (Figure 9, 10, 11, 12,13 & 14) The invention as herein above described should not be read and construed in a restrictive manner as various modifications, alterations and adaptations are possible within the scope and ambit of the invention as defined in the encompassed appended claims. -13- WE CLAIM: 1. A method of manufacturing grinding roller for coal pulverizing In Raymond type pulverizes with replaceable worn out grinding bits comprising the steps of forming grinding bits (05) of high wear resistant material fitted onto a base material of low carbon steel/cast iron, drilling holes (06) on the soft portion of the bits, forming inner base (01) of the roller by casting or by fabricating of plate and machined both on the outside and inside and provided with tapped holes (02) at both sides, the inside surface of the bits having contour in matching relationship with the outside surface of the bases (01), being assembled by connecting 2 to 3 rows of bits by stud rods (09) through tapped holes (02) of the base, the complete roll is formed by assembling the said rows of grinding bits (05) on the base roll (01) by fastening the rows of bits to the base roll with the help of clamping plates (11), screws (08) and nut (10). 2. A method of manufacturing grinding roller as claimed in claim 1 wherein only the worn out grinding bits are replaced by a fresh grinding bit/s by releasing the fastening means of assembled rows of grinding bits in much lesser time. -14- 3. A method of manufacturing grinding roller as claimed in claim 1 wherein the grinding bits have soft metal portion on the outside face along the periphery of the bits and have hard metal portion at the center of the bits or have metal strips inserted between the hard grinding bits, the soft metal portion between the two bits while in operation gets worn out faster than the very hard grinding bits to enable grinding bits project out with gap between them so that these projecting bits act like gear teeth and bite into and plough In the coal, thus securing undisturbed grinding process. 4. A method of manufacturing grinding roller as claimed in the preceding claims wherein inner base (01) of the roller on machining is maintained with conical surface or the top surface of the base is maintained with multiple numbers of flat faces. 5. A method of manufacturing grinding roller as claimed in the preceding claims wherein grinding bits are formed on the base roll (01) by milling dovetailed slots (12) and pushing grinding bits (07) in the dovetailed slots and fixed through clamping plates (11) from sides with the help of screw (08) to the inner base roll (01) and assembled to form complete grinding roll. -15- 6. A method of manufacturing grinding roller as claimed in the preceding claims wherein grinding bits are made of sintered carbide or high chrome or equivalent high resistant wear material, the bits being shrunk fitted onto the carbon steel bit to form the final bit. 7. A method of manufacturing grinding roller as claimed in the preceding claims wherein inside surface of the bits is flat to match with the base and outside surface is conical. 8. A grinding roller for coal pulverizing in Raymond type pulverizer with replaceable worn out grinding bits comprising grinding bits (05) of high wear resistant material fitted onto a base material of low carbon steel/cast iron, drilled holes (6) on the soft portion of the bits, inner base (01) formed by casting or fabricating of plate being machined both on the outside and inside and having tapped holes (02) at both sides, the inside surface of the bits and outside surface of the base (01) is in register relationship within them, the grinding bits (05) are connected in 2 to 3 rows lengthwise by stud rods (09) through tapped holes (02) of the base, the rows of bits being assembled over the base roll (01) by fastening -16- means comprising of clamping plates (11), screws (08) and nut (10) to constitute the completed roll and thus securing easy and faster replacement of worn out grinding bit/s only on releasing the fastening means. 9. The grinding bits of high wear resistant material as formed according to method of claim 1 to constitute a grinding roller for coal pulverizing. Dated this 14th day of May 2007 This invention relates to a method of manufacturing grinding roller for coal pulverizing in Raymond type pulverizers with replaceable grinding bits, grinding roller formed thereof and grinding bits comprising the steps of forming grinding bits (05) of high wear resistant material fitted onto a base material of low carbon steel/cast iron, drilling holes (06) on the soft portion of the bits, forming inner base (01) of the roller by casting or by fabricating of plate and machined both on the outside and inside and provided with tapped holes (02) at both sides, the inside surface of the bits having contour in matching relationship with the outside surface of the base (01), being assembled by connecting 2 to 3 rows of bits by stud rods (09) through tapped holes (02) of the base, the complete roll is formed by assembling the said rows of grinding bits (05) on the base roll (01) by fastening the rows of bits to the base roll with the help of clamping plates (11), screws (08) and nut (10).

Full Text

-2-
FIELD OF THE INVENTION:
The present invention relates to a method of manufacturing grinding
rollers for Raymond type pulverizers and grinding roller formed
thereof with grinding bits. More particularly the present invention
relates to the methods of manufacture and replacement of grinding
roller of frustum-conical shape used to grind coal in vertical spindle
mills of Raymond design,
BACKGROUND OF THE INVENTIN WITH PRIOR ART
DIFFICULTES:
In bowl mill raw coal is fed through center feed pipe. Coal falls at the
center of the rotating bowl. Bowl is lined with replaceable hard liners
called bull ring segments. Due to centrifugal force, the coal starts
moving towards the bowl periphery in a spiraling fashion. In the
existing process the bowl mill is adopted in such a manner that coal
comes between the grinding roll and bull ring segments and gets
crushed. The crushed coal is then carried by the hot air under
pressure to the classifier section for further transportation to the
boiler for firing.
For imparting the grinding pressure required, spring assembly is
provided which presses down the grinding roll on to the bull ring
segments. There are three rolls kept 120 degrees apart. Similarly
there are 3 spring assemblies to press them down. There is provision

-3-
in these mills to adjust the gap between grinding roller and bull ring
segments by moving the grinding roller down and forward. Due to
abrasive nature of the coal, both grinding rollers and bull ring
segments get worn out and gap between them widens. Approximate
life ranges of the bowl mill is from 2000-4000 hours depending on
the material of the wearing elements and abrasiveness of the coal.
Grinding rollers and bull ring segments are replaced periodically.
Grinding rollers for Vertical Pulverizing mills are generally made from
White cast iron outer layer and a soft core of grey/nodular iron. In
this process, which is centrifugal casting, first the white cast iron is
poured at temperature of around 1280 Deg C and immediately after
that grey/nodular iron is poured to form a metallurgical bond. White
cast iron is very hard, which gives wear resistant properties. Ductile
cast iron/nodular iron gives toughness to withstand the impact and it
is easy to machine to match the outside diameter of the housing.
However, rollers made from this method result in a distinct collar
(hump) formation at bigger or smaller or on both ends during the
operation of these rollers. This means that only the center part wears
leaving the edges without much wear. This prevents proper
adjustment of gap between the grinding roller and bullring segments,
resulting in improper grinding.
In vertical spindle mills of Raymond type there is provision to adjust
the gap between the grinding roll and bullring segments by lowering

-4-
or raising the grinding roller. But the pattern of the wear is such that
uniform gap cannot be maintained,
In the conventional roller replacement process, 3 Journal Opening
Cover (door) which give access to the rollers are opened and entire
Journal assembly is taken out and the grinding roller is replaced,
which process is much time consuming.
Another disadvantage of the prior art is that with the passage of time
due to wear action of the coal, the outer surface of the roller
becomes smooth. This leads to slippage of the roller and leads to the
fall in the grinding efficiency.
Another disadvantage of the rollers made from the conventional
casting process (either centrifugally cast or static cast), is that the
entire set of 3 rollers is replaced with a new set. The worn out, which
is thrown, roller weighs approximately between 500 Kilograms to
1200 Kilograms, depending upon the size, of cast/nodular iron with
some amount of nickel or high chrome material stili in it. This leads
to great wastage of natural resources.
The present invention has proposed to remove the difficulties of the
aforesaid prior art disadvantages.

-5-
DESCRIPTION OF THE INVENTION:
One object of the Invention is to propose a method of manufacture of
grinding roiis through mechanically fastened grinding bite, replacing
worn out bits and making the roller new and efficient again.
Another object of the invention is to provide grinding bits
arrangement such that there is soft metal portion between the two
bits, which soft metal portion gets worn out faster than the very hard
grinding bits, to enable the grinding bits project out with gap
between them so that these projecting bits act like gear teeth and
bite Into and plough in the coal thus vastly improving the grinding
process.
An yet another object of the invention is to provide removable
mechanical fastening means for fixing of bits of high wear resistant
material on the top surface of the base roller with clamping plates,
screws or by welding.
With the rollers made form the grinding bits, the entire roller can be
used as It is, after replacing the worn out bits with new bits.
Replacement of the conventional rollers takes about 2 to 3 shifts with
3 to 4 men working. This entails removal of the Journal Opening
Covers, removal of roller assemblies or tilt out roller assemblies.

-6-
This method of replacement entails handling of heavy paits with
cranes, hoists etc.
Replacement of grinding bits according to the invention would take a
fraction of that time of conventional grinding roll for replacement,
thus vastly improving the availability of mills for power generation.
The present invention has developed grinding rollers and method of
producing the grinding rollers for Raymond type pulverizers in a new
approach by forming grinding bits of high wear resistant: material of
sintered earbide or high chrome or equivalent material, with formed
holes In the bits to fix fastening means, forming the base of the roller
through casting or fabrication of plate, tapped holes at both sides of
the rollers, providing clearance/tapped holes in the bits and
maintaining inside surface of the bits having contour in matching
relationship with the conical face of the base, connecting 2 or 3 rows
of bits through stud rods and fastening to the base roller through
clamp plates and screw arrangement through the formed holes in the
grinding bits.
The grinding bits produced according to the invention have soft metal
portions on the outside face of their periphery and have hard metal
portions at the center.
The proposed invention will be better understood from the following
description with reference to the accompanying drawings in which

-16-
means comprising of clamping plates (11), screws (08) and nut
(10) to constitute the completed roll and thus securing easy and
faster replacement of worn out grinding bit/s only on releasing the
fastening means.
9. The grinding bits of high wear resistant material as formed
according to method of claim 1 to constitute a grinding roller
for coal pulverizing.
Dated this 15th day of May 2007
(P.D.GUPTA)
OF L.S. DAVAR&CO.
Applicant's Agents

-7-
Figure 1 and 2 show in perspective view base roller with tapped holes
at both sides of the roller, according to the invention.
Figures 3 &4 show perspective view of both sides of the roll showing
machined top surface of the base roll, according to the invention.
Figure 5 shows a perspective view of a grinding bit with holes
according to the invention.
Figure 6 shows another perspective view of a grinding bit according
to the invention.
Figure 7 shows yet another perspective view of a grind bit according
to the invention.
Figure 8 shows further perspective view or a grinding bit covering the
entire length of a base roll according to the invention.
Figure 9 shows in perspective view a completed assembled roller on
the base roll with 3 rows of grinding bits according to the invention.
Figure 10 shows another perspective view showing form other end of
the complete assembled roll according to the invention.
Figure 11 shows in perspective two rows of assembled grinding bits
over the base roll according to the invention.

-8-
Figure 12 shows in perspective taken from another end the two rows
of bits assembled over the base roll.
Figure 13 shows a perspective view of completely assembled roll with
2 rows of bits according to the invention.
Figure 14 shows another perspective view taken from another side of
the roll showing two rows of assembled grinding bits.
Figure 15 shows a plan view of a base roll with dovetailed slots.
Figure 16 shows a plan view representing the grinding bit to be
engaged in dovetailed sbts of a base roil according to the invention.
Figure 17 shows schematically the pattern of wear of the
conventional grinding roller made from centrifugally cast white cast
iron material.
Figure 18 show haif cross sectional view of the complete assembled
roll with grinding bits and base roll according to the invention.
In conventional grinding roller the wear pattern of roller made from
centrifugally cast white cast iron material is shown in Figure 17. The
figure 17 shows the center part of the roller wears leaving the edges
without much wear. This uneven wear of the roller leads to fall in
throughput and fall in the quality (finesses required) of output. This

-9-
defect leads to coal reject through reject spout, thus wasting the
precious coal.
The present Invention has developed a roller wherein the grinding
bits of a roller are made of high wear resistant material like sintered
carbide or high chrome or other high wear resisting material. The
said grinding bits are shown in figurers 5 to 8 wherein the grinding
bits as one row is shown by reference numeral (05) having clamp
plate (11). These bits are then connected metallurgically to base
material of low carbon steel/cast Iron. Holes (06) are drilled on the
soft portion of the bits (05).
Figures 1 and 2 show the inner base (01) of the roller produced
through either a casting process made of nodular iron or fabrication
through weldabie mild steel plates. The said base of the roller is then
machined both on the outside and inside to have conical surface. The
said base roll (01) has tapped hole (02) at both sides through which
the grinding bits (05) are fastened with base roll by clamping plate
(11) and screws (08), grinding bits (5) have clearance/tapped holes
(06) in them, as shown in figures 5# 6, 7 & 8. Inside surface of the
said bits have contour in register relationship to match with the
conical face of the base. 2 rows or 3 rows of bits are connected
through stud rods (09) and with the help of clamping plate (11), nut
(09) and screws (08) are fastened to the base roller (01). This
fastening means is shown in figure 18. The complete assembled rolls
with 3 rows and 2 rows are shown in figures 9 to 14.

-10-
In another embodiment of the grinding roller manufacture:
1. The bits (05) are made of high wear resistant like sintered
carbide or high chrome or some such material. There are holes
(06) in these bits for fixing. (Figures 5,6, 7,8)
2. The base (01) of the roller is then manufactured through either
a casting process or fabrication through plate method.
3. Then the top surface of the base is machined to obtain a 8, 10,
12 or more number of flat faces. (Figure 3 &4)
4. Base roller has got tapped holes (02) on both sides. (Figure 2)
5. Bits have got clearance/tapped holes (06) in them. (Ref.
Figures 5, 6, 7 & 8). Inside surface of the bits is flat to match
with the base and outside surface is conical.
6. 2 rows or 3 rows of bits (05) are connected through stud rods
(09) and these are in turn fastened to the base roller through
clamp plates (11) and screws (08) arrangement.

-11-
In another embodiment of manufacture of grinding roller;
1. The bits (05) are made of high wear resistant material like
sintered carbide or high chrome or some such material. Bits are
then shrunk fitted onto the carbon steel bit.
2. Inner base (01) of the roller is then manufactured through
either a casting process or fabrication through plate method.
3. Then the top surface of the inner base is machined to obtain a
8, 10, 12 or more number of flat faces 04 (Figure 3) or it is
conical.
4. There are holes (06) in the carbon steel portion of the bits for
fixing (Figures 5, 6, 7, 8). Inside profile of the bits matches
with the outside profile of the base.
5. 2 rows or 3 rows of bits are connected through stud rods (09)
and these are in turn fastened to the base roller through clamp
plates (11) and screws arrangement (08).

-12-
In another embodiment of method of manufacture of
grinding roller:
1. Dovetailed slots (12) are milled on the base roller (01). (fig.15).
The top surface of which could be conical or having 8 to 10
flats surfaces.
2. Bits (07) (fig. 16) are pushed in these dovetailed slots.
3. These bits are fixed through clamp plates (11) from sides,
which are fixed with screw (08) to the inner base roll (01).
(Figure 9, 10, 11, 12,13 & 14)
The invention as herein above described should not be read and
construed in a restrictive manner as various modifications, alterations
and adaptations are possible within the scope and ambit of the
invention as defined in the encompassed appended claims.

-13-
WE CLAIM:
1. A method of manufacturing grinding roller for coal pulverizing
In Raymond type pulverizes with replaceable worn out grinding
bits comprising the steps of forming grinding bits (05) of high
wear resistant material fitted onto a base material of low
carbon steel/cast iron, drilling holes (06) on the soft portion of
the bits, forming inner base (01) of the roller by casting or by
fabricating of plate and machined both on the outside and
inside and provided with tapped holes (02) at both sides, the
inside surface of the bits having contour in matching
relationship with the outside surface of the bases (01), being
assembled by connecting 2 to 3 rows of bits by stud rods (09)
through tapped holes (02) of the base, the complete roll is
formed by assembling the said rows of grinding bits (05) on the
base roll (01) by fastening the rows of bits to the base roll
with the help of clamping plates (11), screws (08) and nut
(10).
2. A method of manufacturing grinding roller as claimed in claim 1
wherein only the worn out grinding bits are replaced by a fresh
grinding bit/s by releasing the fastening means of assembled
rows of grinding bits in much lesser time.

-14-
3. A method of manufacturing grinding roller as claimed in claim 1
wherein the grinding bits have soft metal portion on the outside
face along the periphery of the bits and have hard metal
portion at the center of the bits or have metal strips inserted
between the hard grinding bits, the soft metal portion between
the two bits while in operation gets worn out faster than the
very hard grinding bits to enable grinding bits project out with
gap between them so that these projecting bits act like gear
teeth and bite into and plough In the coal, thus securing
undisturbed grinding process.
4. A method of manufacturing grinding roller as claimed in the
preceding claims wherein inner base (01) of the roller on
machining is maintained with conical surface or the top surface
of the base is maintained with multiple numbers of flat faces.
5. A method of manufacturing grinding roller as claimed in the
preceding claims wherein grinding bits are formed on the base
roll (01) by milling dovetailed slots (12) and pushing grinding
bits (07) in the dovetailed slots and fixed through clamping
plates (11) from sides with the help of screw (08) to the inner
base roll (01) and assembled to form complete grinding roll.

-15-
6. A method of manufacturing grinding roller as claimed in the
preceding claims wherein grinding bits are made of sintered
carbide or high chrome or equivalent high resistant wear
material, the bits being shrunk fitted onto the carbon steel bit
to form the final bit.
7. A method of manufacturing grinding roller as claimed in the
preceding claims wherein inside surface of the bits is flat to
match with the base and outside surface is conical.
8. A grinding roller for coal pulverizing in Raymond type pulverizer
with replaceable worn out grinding bits comprising grinding bits
(05) of high wear resistant material fitted onto a base material
of low carbon steel/cast iron, drilled holes (6) on the soft
portion of the bits, inner base (01) formed by casting or
fabricating of plate being machined both on the outside and
inside and having tapped holes (02) at both sides, the inside
surface of the bits and outside surface of the base (01) is in
register relationship within them, the grinding bits (05) are
connected in 2 to 3 rows lengthwise by stud rods (09) through
tapped holes (02) of the base, the rows of bits being
assembled over the base roll (01) by fastening

-16-
means comprising of clamping plates (11), screws (08) and nut
(10) to constitute the completed roll and thus securing easy and
faster replacement of worn out grinding bit/s only on releasing the
fastening means.
9. The grinding bits of high wear resistant material as formed
according to method of claim 1 to constitute a grinding roller
for coal pulverizing.
Dated this 14th day of May 2007

This invention relates to a method of manufacturing grinding roller
for coal pulverizing in Raymond type pulverizers with replaceable
grinding bits, grinding roller formed thereof and grinding bits
comprising the steps of forming grinding bits (05) of high wear
resistant material fitted onto a base material of low carbon steel/cast
iron, drilling holes (06) on the soft portion of the bits, forming inner
base (01) of the roller by casting or by fabricating of plate and
machined both on the outside and inside and provided with tapped
holes (02) at both sides, the inside surface of the bits having contour
in matching relationship with the outside surface of the base (01),
being assembled by connecting 2 to 3 rows of bits by stud rods (09)
through tapped holes (02) of the base, the complete roll is formed by
assembling the said rows of grinding bits (05) on the base roll (01)
by fastening the rows of bits to the base roll with the help of
clamping plates (11), screws (08) and nut (10).

Documents:

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Patent Number

255097

Indian Patent Application Number

751/KOL/2007

PG Journal Number

04/2013

Publication Date

25-Jan-2013

Grant Date

22-Jan-2013

Date of Filing

15-May-2007

Name of Patentee

BHARAT HEAVY ELECTRICALS LIMITED

Applicant Address

REGIONAL OPERATIONS DIVISION (ROD), PLOT NO: 9/1, DJBLOCK 3RD FLOOR, KARUNAMOYEE, SALT LAKE CITY, KOLKATA-700091, HAVING ITS REGISTERED OFFICE AT BHEL HOUSE, SIRI FORT, NEW DELHI-110049

Inventors:

#	Inventor's Name	Inventor's Address
1	SATISH GHATGE	BHEL, RAMACHANDRAPURAM, HYDERABAD-502032
2	BADUR KRISHNAN	BHEL, RAMACHANDRAPURAM, HYDERABAD-502032
3	J.G. KULKARNI	BHEL, RAMACHANDRAPURAM, HYDERABAD-502032

PCT International Classification Number

B02C4/30; B02C4/00

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1			NA