FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
(Se section 10, rule 13)
INSTALLATION OF LINERS IN A TUBE MILL, TUBE MILL PROVIDED
WITH LINERS'
We, AIA Engineering Ltd., of 115, G.V.M.M. Estate, Odhav Road, Ahmedabad - 382 410, India;
The following specification particularly describes and ascertains the invention and the manner in which it is to be performed.
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INSTALLATION OF LINERS IN A TUBE MILL, TUBE MILL PROVIDED WITH LINERS
ABSTRACT
The invention relates to a tube mill provided with liners fastened to a shell. The invention also relates to a method for installing liners in a tube mill.
Prior art
A large number of tube mills used for grinding and pulverizing applications have drilling pattern with a pitch of 250mm in longitudinal direction and 314mm in circumferential direction. This standard has been adopted all over the world as a DIN standard. However, there are some mills, most of which are old mills, which are termed as non-DIN standard mills having drilling pattern in many different varieties. Installation of DIN standard liners in such mills posses many problems. Fitting and fastening the liners in the mill requires liners to be designed separately for each mill. It is an aim of the invention to provide an arrangement for enabling installation of DIN standard liners of boltless configuration in non-DIN standard mills.
Object of invention
To this end the tube mill in accordance with the invention is characterized in that the tube mill is provided with an adaptor plate, the adaptor plate being provided with a first pattern of drilling holes in a DIN pattern and a second pattern of drilling holes in a non-DIN pattern wherein the adaptor plate is fastened to the shell via one or more of the holes of the second patterns and a number of liners is fastened to the adaptor plate via one or more holes of the first pattern. The method of installation of liners is characterized in that an adaptor plate provided
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with a first pattern of drilling holes in a DIN pattern and a second pattern of drilling holes in a non-DIN pattern, liners are attached to the adaptor plate via one or more holes of the first pattern and the adaptor plate is attached to the shell via one or more holes of the second pattern.
In some embodiments, the first and the second patterns do not have any hole in common. Preferably, after fixing of at least two rows of bolted liners, rows of unbolted liners are installed.
Brief description of the drawings
These and other advantageous aspects of the invention will be described in more detail using the following figures.
FIG. 1 and illustrate a typical arrangement of a tube mill comprising DIN Liners
FIG. 2 3D representation of installation of DIN liners on DIN shell
FIG. 3 illustrates a shell of a tube mill provided with an adaptor plate according to
the invention
FIG. 4 illustrates the installation of one bolted row of DIN liners in a tube mill
having non DIN drilling, using the adaptor plate.
The figures are not drawn to scale. Generally, identical components are denoted by the same reference numerals in the figures.
Detailed description of embodiments of the invention
All the tube mills used for grinding and pulverization of minerals such as clinker or coal are fitted with liners. The liners have the function of protecting the shell and of distributing the grinding media in the mill so that crushing efficiency is improved. These liners are affixed on the shell using fastening devices.
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Installation of liners without use of fasteners is also common and a variety of arrangements are used. Installation of liners without fasteners has many advantages over liners installed with fasteners. Loosening/breakage of fastener can cause displacement of the liners from its position and consequent damage in the mill. The fasteners have to be retightened at regular intervals at least at the beginning of the campaign with new liners which is not required in case of liners without fasteners. There is always chance of leakage of ground material in the case of liners with fasteners causing environmental damage. There is less chance of breakage of liners without bolt-holes. Due to these operational and process advantages, present invention proposes in an embodiment a system to install boltless liners as per DIN standard on a shell with non-DIN drilling.
Figures 1 and 2 illustrate a typical arrangement of DIN liners 1 on a shell 2. The shell 2 is provided with holes 4, and the liner with holes 3. Through the holes 3 in the liners bolts, here not shown, are provided. The threaded bolts are fastened with a nut and washer from outside the shell.
In the case of DIN standard mills, installation of boltless liners is well standardized and production of boltless liners is much easier with DIN standard mills. However, boltless liners have to be designed separately for each non-DIN standard mill. Present invention has removed this limitation. The adaptor plate provides for a convenient, easy and safe way of installing DIN-type liners in a non-DIN standard mill.
Installation of DIN standard boltless liners on non DIN standard shell requires installation of one bolted row each at the two ends of mill chamber in circumferential direction and at least two bolted liner rows in longitudinal direction. The arrangement for installation of bolted row in non-DIN mill is shown in figure 3. The figure 3 shows the shell 2 of the mill with holes 4' with a pitch of one foot (non-metric) in longitudinal direction. An adaptor plate 5 is mounted on the shell and has a pattern of holes 6 with a drilling pitch of one foot.
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The plate has a second pattern of threaded hole 7 arrangement at 250 mm pitch, i.e. at DIN pitch.
Bolted liners are installed on the adaptor plates as shown in figure 4. The figure shows cross section at one foot pitch and cross section at 250 mm pitch. A mill may require either two or more such rows in longitudinal direction (two rows at 180 degrees, three rows at 120 degrees and so on) in order to support the boltless liners between these bolted rows.
After two or more such bolted rows in longitudinal direction and first and last bolted rows have been installed, installation of boltless liners can proceed.
Examples
In one 3.048 M dia mill, the longitudinal pitch is 380 mm. In this mill boltless liners as per DIN standard design were installed using an adaptor plate with a pattern of holes with a longitudinal non-DIN pitch of 380 mm and a pattern of threaded holes with a DIN pitch of 250 mm as illustrated above. The mill installed for the purpose of reasonable trial and experimentation has completed 1000 hours of operation and continues to run satisfactorily with normal output till date.
Another 3.4 M dia mill with a longitudinal pitch of 378 mm was fitted with boltless liners using an adaptor plate with a pattern of holes with a longitudinal non-DIN pitch of 378 mm and a pattern of threaded holes with a DIN pitch of 250 mm as illustrated above. The mill installed for the purpose of reasonable trial and experimentation has completed 1000 hours of operation and continues to run satisfactorily with normal output till date.
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WE CLAIM:
1. A tube mill provided with liners (1) fastened to a shell (2), characterized in
that the tube mill is provided with an adaptor plate (5), the adaptor plate being provided with a first pattern of drilling holes (7) in a DIN pattern and a second pattern of drilling holes (6) in a non-DIN pattern wherein the adaptor plate is fastened to the shell via one or more of the holes of the second patterns and a number of liners is fastened to the adaptor plate via one or more holes of the first pattern.
2. A method for installing liners in a tube mill, characterized in that an adaptor plate provided with a first pattern of drilling holes in a DIN pattern and a second pattern of drilling holes in a non-DIN pattern liners are attached via the holes of the first pattern and the adaptor plate is attached to the shell via one or more holes of the second pattern.
3. A method as claimed in claim 2, characterized in that, after fixing of at least two rows of bolted liners, rows of unbolted liners are installed.
4. A tube mill provided with liners fastened to a shell substantially as herein above described and with reference to the accompanying drawings.
5. A method for installing liners in a tube mill substantially as herein above described and with reference to the accompanying drawings.
Dated this 2nd day of May, 2007
G. Deepak Sriniwas
Of K&S Partners
Agent for the Applicants.
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Abstract:
A tube mill is provided with liners (1) fastened to a shell (2). Tube mill is provided with an adaptor plate (5). The adaptor plate is provided with a first pattern of drilling holes (7) in a DIN pattern and a second pattern of drilling holes (6) in a non-DIN pattern. The adaptor plate is fastened to the shell via one or more of the holes of the second patterns and a number of liners is fastened to the adaptor plate via one or more holes of the first pattern.
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