Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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BACKING ASSEMBLY FOR USE IN Z-MILL TYPE ROLLING MILLS
SCOPE OF THE INVENTION
The present invention relates to metal working rolling mills, and more
particularly a cluster mill or Z-mill, which includes one or more backing
assemblies
having a lubricant delivery system for supplying high viscosity lubricating
fluids to mill
roller bearings, independently from rolling fluids.
BACKGROUND OF THE INVENTION
Z-mills, also known as cluster mills, 20 High Mills, or "Sendzimir" mills, are
well known for use in metal working applications. Figure 1 shows a
conventional Z-mill
construction, as for example is described in United States Patent No.
4,289,013 to
Hunke, the disclosure of which is incorporated herein by reference, and which
is used in
the rolling of metal strips 12.
The Z-mill 10 includes a pair of work rolls 14 which engage and work the metal
strip 12 as it is moved back and forth therebetween. The work rolls 14 are
supported by
four first intermediate rolls 16. The first intermediate rolls 16 are in turn,
supported by
six secondary intermediate rolls, each identified generally as 18, and which
include
driven rolls 18' and idler rolls 18". The second intermediate rolls 18 are
themselves
supported by eight backing assemblies 20 which are mounted within a
surrounding
housing 22 at positions ABCDEFG and H.
Figure 2 shows best a cross-sectional view of a conventional backing assembly
20 as including between four and eight roller bearings 24 which are rotatably
mounted
on a cylindrical backing shaft 26. The backing shaft 26 is mounted to the
housing 22 by
a series of longitudinally spaced saddle assemblies 28, which rotatably
support the shaft
26 in the housing 22 so as to be rotatable along an eccentric path, allowing
the shaft 26
and roller bearings 24 to reciprocally move vertically relative to the metal
strip.
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As the Z-mill 10 is operated in the rolling of the metal strip 12, rolling
fluid is
pumped from a reservoir and sprayed via nozzles 29 (Figure 1) onto the upper
and lower
surfaces of the sheet 12 as it travels between the work rolls 14.
Concurrently, rolling
fluid is pumped under pressure via a supply line 30 into a hollow bore 32
which extends
axially down the centre of the backing shaft 26, flowing outwardly therefrom
through a
series of holes 34, to provide lubrication to each roller bearing 24.
Typically, rolling fluids are low viscosity oils or emulsions of water and
oil. In
particular, to achieve proper rolling of the steel sheet 12, rolling fluids
are selected from
low viscosity fluids having viscosities of about ISO 4 VG (viscosity grade) or
less.
Conventional Z-mills 10 suffer a disadvantage in that heretofore, large
volumes of
rolling fluid are required to ensure adequate lubrication of the roller
bearings 24. In
particular, the use of conventional low viscosity rolling fluids to lubricate
the roller
bearings 24 necessitates that the lubricating fluid be supplied to the backing
shaft 26 in
volumes of up to 1000 litres per minute, with up to 35% by volume of the total
rolling
fluid used in the Z-mill being diverted into the mill roller bearings 24.
Although it is
known to recirculate rolling fluid in Z-mills for reuse, the loss of rolling
fluids associated
with prior art constructions results in increased manufacturing costs and
inefficiencies.
Prior art Z-mills suffer a further disadvantage in that the flooding of the
backing
assembly roller bearings 24 with high volumes of rolling fluids tends to
increase the
amount of heat generated, producing a corresponding loss of power. In addition
to
increased manufacturing costs associated with higher power consumption rates,
the
increased temperatures accelerate the degradation of the lubricating
properties of the
rolling fluid, increasing further overall rolling fluid consumption.
As a result of their lower viscosities and in the case of emulsions, high
water
content, rolling fluids are therefore poorly suited to lubricate the backing
assembly
bearings. The applicant has appreciated that preferably, roller bearings
should be
lubricated with high viscosity lubricants having viscosities of greater than
about ISO 150
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VG (viscosity grade - average viscosity at 40 C mm2/S), and more preferably
about ISO
100 VG, which are less susceptible to thermal degradation.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a system for
lubricating the roller bearings of a Z-mill backing assembly with high
viscosity
lubricating fluids, and more preferably lubricating fluids containing oils
having
viscosities of greater than about ISO 50 VG, preferably greater than about ISO
80 VG,
and most preferably about ISO 100 VG.
Another object of the invention is to provide a backing assembly for a Z-mill
which includes a lubricant supply assembly operable to continuously supply a
gas/oil
lubricant mixture to each backing assembly roller bearing, while the backing
assembly
shaft is rotated in eccentric movement.
A further aspect of the invention is to provide a Z-mill which incorporates
one or
more backing assemblies which include a lubricant supply apparatus which is
operable to
supply a substantially water-free lubricating fluid to backing rollers,
independently from
the rolling fluid used in metal rolling operations.
Another object of the invention is to provide a Z-mill which incorporates one
or
more backing assemblies in which the assembly roller bearings are
independently
lubricated with a lubricating oil supplied as part of an all-loss system using
smaller
quantities of oil, and without requiring the recirculation and filtration of
lubricating
fluids.
To at least partially overcome some of the difficulties associated with prior
art
devices, the present invention provides for a backing assembly for use in a Z-
mill, a
cluster mill, 20 High Mill or Sendzimir mill (hereinafter generally referred
to as a Z-
mill). The backing assembly includes a lubricant supply assembly and an
elongated
backing shaft which includes a number of longitudinally spaced bearing support
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surfaces, each configured to rotatably support a cylindrical roller bearing
thereon.
Preferably, the backing shaft is elongated along a central axis having a
longitudinal
length selected to support a number, and most preferably between 4 and 8
roller bearings
thereon, although fewer or greater numbers of roller bearings may be used. The
backing
shaft is adapted to be rotatably secured to a Z-mill housing by one or more
saddle
assemblies. The saddle assemblies may be of a conventional design and include
saddle
bearings which support the backing shaft so as to be rotatably movable
relative to the
housing along a generally eccentric path. Most preferably, saddle bearings
support the
backing shaft so as to be reciprocally movable in a direction relative to said
metal strip,
selected at between about 0.5 and 5 mm, and preferably about 3 mm.
A series of lubricant feed channels are formed along at least part of the
interior of
the bearing shaft, and permit the flow of bearing lubricating fluid therealong
to outlets
adjacent to each bearing support surface. Although not essential, most
preferably each
lubricant feed channel is formed as a discrete channel which extends from a
channel inlet
formed in one end of the bearing shaft, axially through the shaft, to an
outlet which
opens directly into a respective bearing mounting surface to which each roller
bearing is
secured.
The lubricant supply assembly is provided to supply a lubricating fluid under
pressure to the lubricant feed channels as the backing shaft is eccentrically
moved. In a
simplified construction, the lubricant supply assembly communicates with or
includes a
pressurized source of a gas such as air, a pressurized oil source and
optionally, a supply
manifold downstream and in fluid communication with the gas and oil sources.
The
supply manifold preferably includes internal valving, such as one or more
needle valves,
which are operable to regulate the volume and timing of gas and oil flow
therethrough.
In this manner, the supply manifold may be used to regulate and supply a
pressurized
gas/oil mixture of lubricating fluid into each channel inlet of the lubricant
feed channels,
in operation of the Z-mill.
In a preferred construction, the supply manifold is provided in fluid
communication with a bearing assembly which fluidically couples the lubricant
supply
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assembly to the backing shaft. The bearing assembly is downstream from the
supply
manifold and includes a bearing plate which is fixed against rotation relative
to the
housing, in which are provided one or more lubricant outlet ports fed via the
manifold.
The bearing plate is configured for juxtaposed placement with the channel
inlets formed
in a selected adjacent end of the backing shaft. Preferably, the outlet ports
and channel
inlets are formed with complementary shapes selected to maintain at least
partial fluidic
coupling therebetween, as the adjacent end of the backing shaft eccentrically
moves
relative to the bearing plate. One or more sealing members, such as a rotary
seal, a
labyrinthine type seal or a compressible 0-ring are preferably also provided
to maintain
substantially fluid sealing contact between the bearing plate and at least
part of the
adjacent end of backing shaft 26, to prevent the movement of lubricant fluid
therebetween as the backing shaft 26 is rotated.
Although not essential, the bearing plate may be axially movable from a first
position spaced towards and in engaging juxtaposition with at least part of
the adjacent
end of the backing shaft, and a second position moved remote therefrom. One or
more
biasing members, such as a resiliently compressible or extensible springs, gas
struts or
pistons or other resiliently compressible member may be provided to
resiliently bias the
bearing plate to the first position against the shaft end.
Optimally, the applicant has discovered that a lubricant fluid consisting of a
gas
and oil mixture may be used to lubricate the roller bearings independently of
the low
viscosity rolling fluids used in rolling operations. More preferably, the
bearing lubricant
fluid used in the backing assembly to lubricate the roller bearings is
supplied as an "all
loss" lubricating system, whereby the lubricating fluid is supplied in volumes
of less than
about 4 litres per hour, so as to be fully consumed in the operation of the Z-
mill. Most
preferably, the lubricant fluid consists of air/oil droplet lubricant
mixtures, with the oil
selected from high pressure oils having a viscosity of at least about ISO 50
VG,
preferably at least about ISO 75 VG, and most preferably about ISO 100 VG. The
high
viscosity oil is most preferably selected so as to be compatible with the mill
rolling fluid,
where excess oil enters the rolling fluid reservoir.
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Accordingly, in one aspect the present invention resides in a backing assembly
for a Z-mill type rolling mill, the assembly comprising,
a backing shaft being elongated in a longitudinal direction along a shaft axis
and
extending from a first shaft end to a second shaft end, the backing shaft
defining a
plurality of longitudinally spaced cylindrical bearing mounting surfaces, and
further
including a plurality of lubricant feed channels extending axially through
said shaft, each
of said feed channels providing fluid communication between an associated
channel inlet
open to said first shaft end and a respective lubricant outlet orifice
disposed in an
associated one of said bearing mounting surfaces,
a plurality of bearings, each of the bearings including a cylindrical bore
having a
radial diameter selected marginally greater than a radial diameter of the
bearing
mounting surfaces, each said bearing being mounted on a respective bearing
mounting
surface so as to be rotatable thereon relative to said backing shaft,
a saddle assembly for supporting said shaft in rotational movement with said
first
shaft end being movable along a generally eccentric path, the saddle assembly
including
at least one saddle bearing surface engaging said backing shaft at a location
spaced from
said bearing mounting surfaces,
a lubricant supply assembly for supplying a lubricant under pressure to each
said
channel inlet as said first shaft end moves along said eccentric path, said
supply
assembly including a fluid flow assembly and a bearing member, the bearing
member
having an end face configured for juxtaposed contact with at least part of
said backing
shaft first end, the bearing member being movable in a generally axial
direction between
a first position where said end face is moved into substantially juxtaposed
contact with at
least part of said backing shaft first end, and a second position spaced
rearwardly
therefrom,
a biasing member for resiliently biasing the bearing member to the first
position,
the fluid flow assembly providing fluid communication between at least one
fluid
supply and a lubricant outlet port disposed in said bearing surface, the
outlet port being
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positioned for at least partial fluid communication with at least one feed
channel inlet
when the bearing member is moved to the first position.
In another aspect, the present invention resides in a backing assembly for a
rolling mill comprising,
a backing shaft being elongated in a longitudinal direction along a shaft
axis, and
extending from a first shaft end to a second shaft end,
the backing shaft defining a plurality of longitudinally spaced cylindrical
bearing
mounting surfaces, and further including a plurality of lubricant feed
channels extending
axially along an interior portion of said shaft, each of said lubricant feed
channels
providing fluid communication between an associated channel inlet open to said
first
shaft end and a channel outlet disposed in a respective one of said bearing
mounting
surfaces,
an associated cylindrical roller bearing rotatably mounted on each of said
bearing
mounting surface,
a saddle assembly rotatably supporting said first shaft end in movement along
a
generally eccentric path, the saddle assembly including at least one saddle
bearing
surface engaging said backing shaft intermediate an adjacent pair of said
bearing
mounting surfaces,
the first shaft end further including a seating surface extending annularly
about
said channel inlets,
a lubricant supply assembly for supplying a lubricant fluid under pressure to
each
said channel inlet,
said lubricant supply assembly including a bearing plate having a lubricant
fluid
outlet port and a fluid flow assembly, the fluid flow assembly providing fluid
communication between at least one fluid supply and an outlet port formed in
said
bearing plate, the bearing plate being movable in a generally axial direction
into
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juxtaposed contact with the first shaft end to provide at least partial fluid
communication
between the outlet port and the channel inlets,
an annular seal member disposed on said bearing plate and extending radially
about said outlet port, the seal member being movable together with the
bearing plate
into sealing contact with said seating surface to substantially prevent the
movement of
lubricant fluid therebetween as said backing shaft is rotated.
In a further aspect, the present invention resides in a Z-mill type rolling
mill
comprising,
a housing,
a plurality of backing shafts mounted in said housing, each of said backing
shafts
being elongated along a longitudinal axis and extending from a first shaft end
to a second
shaft end, and defining at least two longitudinally spaced cylindrical bearing
mounting
surfaces, a plurality of lubricant feed channels extending axially along a
portion of said
shaft, said feed channels providing fluid communication between an associated
inlet
open to said first shaft end and a lubricant outlet disposed in a respective
one of said
bearing mounting surfaces, the first shaft end including a generally flat
seating surface
extending as an annular surface about said feed channel inlets generally
normal to said
shaft axis,
an associated cylindrical bearing rotatably mounted on each of said bearing
mounting surface,
a plurality of saddle assemblies rotatably supporting said shaft in said
housing
with said first shaft end being movable along a generally eccentric path, each
saddle
assembly including at least one saddle bearing surface engaging said backing
shaft,
a manifold fixed against rotation relative to said housing and for regulating
the
supply of a lubricant fluid under pressure to each said associated channel
inlet,
a bearing member provided for juxtaposed contact with the first shaft end, the
bearing member including a bearing plate having a plurality of outlet feed
holes formed
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therein, the manifold being in fluid communication with a fluid supply and the
outlet
feed holes disposed in said bearing member,
the bearing member being movable in a generally axial direction between a
sealing position wherein the bearing plate is moved into juxtaposed contact
with at least
part of said first shaft end to fluidically communicate the at least one of
the feed holes
with a selected feed channel inlet so as to permit the flow of said lubricant
therein, and a
second position moved a distance therefrom,
an annular seal member disposed on said bearing plate radially about said feed
holes, the bearing plate being axially displaceable between a sealing position
wherein
said annular sealing member is in sealing contact with a biasing member, for
resiliently
biasing the bearing plate towards the sealing position, and
wherein the lubricant fluid comprises a mixture of air and high viscosity oil.
BRIEF DESCRIPTION OF THE DRAWINGS
Reference may now be had to the following detailed description taken together
with the accompanying drawings in which:
Figure 1 illustrates schematically a cross-sectional view of the roller
configuration used in a conventional Z-mill;
Figure 2 illustrates a cross-sectional view of a conventional backing assembly
used in the Z-mill of Figure 1;
Figure 3 illustrates a partial cross-sectional side view of a backing assembly
for
use in a Z-mill in accordance with a preferred embodiment of the invention;
Figure 4 illustrates an exploded cross-sectional plan view of the backing
assembly shown in Figure 3;
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Figure 5 illustrates schematically an exploded partial perspective view of the
backing assembly of Figure 3 showing a lubricant supply assembly used to
supply high
viscosity lubricating fluids to a backing shaft and backing roller bearings in
accordance
with a preferred embodiment of the invention;
Figure 6 illustrates an enlarged partial cross-sectional view showing the
engagement of the lubricant supply assembly shown in Figure 4 in the backing
assembly
shaft; and
Figures 7 to 12 illustrate schematically the positioning of the outlet feed
holes of
the lubricant supply assembly relative to the inlet openings of the lubricant
feed
channels, as the end of the backing shaft is moved eccentrically.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Figure 3 illustrates schematically a backing assembly 40 for use in a Z-mill
type
rolling mill 10 of the type shown in Figure 1, in accordance with a preferred
embodiment
of the invention. It is to be appreciated that in assembly, the backing
assembly 40 of
Figure 3 may be substituted for one or more of the conventional backing
assemblies 20
shown in Figure 1, to engage and support the intermediate rolls 18 in the
operation of the
Z-mill 10. In use of the present invention, rolling of the metal strip 12 is
effected in
essentially the same manner as prior art devices, with low viscosity rolling
fluid sprayed
onto the upper and lower strip surfaces by way of spray nozzles 29 (Figure 1),
while a
high viscosity, high temperature air/oil lubricant fluid mixture being fed to
each backing
assembly 40, independently from the rolling fluid.
Unlike conventional Z-mills, the air/oil lubricant fluid mixture used to
lubricate
components of the backing assembly 40 of the present invention consists of a
mixture of
about 96 to 99% by volume air and 4 to 1% by volume high viscosity oil, and
most
preferably about 99% by volume air and 1% by volume oil. The oil has a
preferred
viscosity of about ISO 100 VG. Suitable oils may therefore include gear oils,
petroleum
based oils and/or oils containing sulphur and/or phosphorous as extreme
pressure
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additives. Most preferably, the oil is present in the air/oil mixture in the
form of
individual droplets having a mean droplet size selected at between about .005
to .2 mm
and more preferably about.01 to .05 mm.
The backing assembly 40 is shown best in Figures 3 and 4 as including a
cylindrical backing shaft 46 along which are rotatably mounted a number of
cylindrical
roller bearings 44, and a lubricant supply assembly 42 which in operation
supplies an
air/oil droplet mixture as a roller bearing lubricating fluid to the bearing
shaft and each of
the roller bearings 44.
In the embodiment shown, the backing shaft 46 is longitudinally elongated
along
a central shaft axis As-As (Figure 4), extending from a first shaft end 45
which is
proximate to the lubricant supply assembly 42 to a second shaft end 47 remote
therefrom. The backing shaft 46 is generally cylindrical and defines a number
of axially
spaced cylindrical bearing mounting surfaces 48a,48b,48c,48d.
Figure 3 shows best each of the roller bearings 44a,44b,44c,44d as having a
cylindrical central bore 50 formed therethrough. The cylindrical bores 50 are
formed
with a diameter which is marginally greater than that of a corresponding
mounting
surface 48a,48b,48c,48d, allowing the rotational mounting of the bearings
44a,44b,44c,44d in alignment respectively therewith on the shaft 46.
The backing shaft 46 is in turn rotatably mounted in the Z-mill housing 22 by
a
series of axially spaced saddle assemblies 28a,28b,28c,28d,28e. The saddle
assemblies
28a,28b,28c,28d,28e each include at least one saddle bearing 54 which
rotatably engages
the backing shaft 46 at locations spaced from the roller bearings
44a,44b,44c,44d, so as
to effect movement of the shaft 46 along an eccentric path. Most preferably,
the saddle
bearings 54 support the backing shaft 46 in eccentric movement, so as to be
reciprocally
displaceable in a direction towards and away from the metal strip 12 (Figure
1).
Depending on the mounting location ABCDEFGH (Figure 1), the saddle assemblies
28
typically movably support the backing shaft 46 with the first shaft end 45 so
as to be
movable in a horizontal plane relative to the feed direction of the metal
strip 12 a
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distance of between about I and 6 mm. In particular, the backing shafts 46
mounted at
outboard positions ADEH are typically mounted so as to be vertical
displaceable by a
distance of about 3.3 mm. The backing shafts 46 positioned at inboard
locations BCFG
are frequently movable in a horizontal plane generally parallel to the feed
direction by a
distance of between about I and 6 mm, and typically with a displacement of
about 5.4
mm. In addition, the saddle bearings 54 further define the lateral extent of
the bearing
mounting surfaces 48a,48b,48c,48d and assist in maintaining the roller
bearings
44a,44b,44c,44d in alignment therewith, as the Z-mill 10 is operated.
Figures 3 and 4 shows best four discrete lubricant feed channels
60a,60b,60c,60d
as being formed along the interior of the backing shaft 46 which as will be
described,
communicate the roller bearing lubricant from the lubricant supply assembly 42
to each
bearing mounting surface 48a,48b,48c,48d. Each lubricant feed channel
60a,60b,60c,60d has a minimum average diameter of about 0.5 to 7 mm, and
preferably
about 4 mm, and extends along an interior of the backing shaft 46 generally
parallel to
axis As-As. The feed channels 60 extend from a respective inlet opening
62a,62b,62c,62d (Figure 5) open to the first shaft end 45, to a respective
outlet orifice
64a,64,64c,64d, permitting fluid flow thereto. The outlet orifices
64a,64b,64c,64d are
open respectively into each bearing mounting surface 48a,48b,48c,48d. Although
not
essential, each outlet orifice 64a,64b,64c,64d is most preferably formed
having three
axially spaced radially extending aperture passages 68 which each fluidically
communicate with a bottom portion of an associated radially extending groove
70
formed about a periphery of the shaft 42.
Figure 5 illustrates best the inlet openings 62a,62b,62c,62d of each lubricant
feed
channel 60a,60b,60c,60d. The inlet openings 62 are provided as opposing pairs
of
radially extending recesses 60a,60b and 60c,60d which extend about the shaft
axis As-
As. Each of the inlet openings 62a,62b,62c,62d extend about the axis As-As a
radial arc
selected at between about 90 and 175 and most preferably between about 140
and
170 . Although not essential, most preferably the pairs of inlet openings
62a,62b and
62c,62d are offset relative to the shaft axis As-As from each other at
approximately 90
for simplified manufacture. The first opposing pair of openings 62a,62b is
provided at a
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first radial distance D, (Figure 7) spaced from the shaft axis As-As, with the
second pair
of openings 62c,62d spaced radially outwardly from the axis As-As by a
distance D2
(Figure 7).
As shown best in Figure 5, the portion of shaft end 45 which extends radially
about the second pair of inlet openings 62c,62d is preferably formed as a
substantially
smooth seating surface 65. Most preferably, the seating surface 65 is oriented
normal to
and extends radially from the axis As-As by a distance at least equal to, and
preferably
greater than, the distance between the major and minor axis of the elliptical
path along
which the shaft end 45 travels.
Figure 5 illustrates best a peripheral edge of the end 45 of backing shaft 46
as
having a gear tooth profile 70 which extends about the entirety of the shafts
46 used in
positions ADEH (Figure 1). It is to be appreciated that depending on the
positioning of
the backing assembly 42, the gear tooth 70 could extend only in a partial
radial path,
where for example the backing assembly 42 is provided in positions BCFG. The
gear
tooth profile 70 is engageable with a drive gear and/or a rack and hydraulic
cylinder (not
shown) in all or selected positions in the operation of the Z-mill 10 to drive
the shaft 46
in rotation about the shaft axis As-As.
Figures 4 to 6 show the lubricant supply assembly 42 used to regulate the flow
of
the air/oil lubricating fluid mixture from a pressurized air source 72 and
pressurized oil
source 74 into the lubricant feed channels 60a,60b,60c,60d of the backing
shaft 46. As
shown best in Figure 5, the lubricant supply assembly 42 includes a supply
manifold 76,
conduit tubing 78 which fluidically couples the air source 72 and oil source
74 to the
manifold 76, and a thrust bearing assembly 80. As will be described, the
thrust bearing
assembly 80 is used to maintain fluid communication with the backing shaft 46
as it
eccentrically moves to maintain a steady supply of lubricating fluid thereto.
The supply manifold 76 includes an air/oil injector block housing 82 which is
provided immediately downstream from the infeed ends of the conduit tubing 78.
A
needle valve assembly 84 is housed within the injector block housing 84. The
needle
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valve assembly 84 is provided with valving which is operable to independently
regulate
the flow of air and oil into and through the lubricant supply manifold 76. In
a preferred
mode of operation, the needle valve assembly 84 is operable to provide a
lubricant fluid
mixture which consists of 99 % by volume air and about 1% by volume high
viscosity
oil, at an output flow rate being regulated through the manifold 76. Most
preferably the
needle valve assembly 84 is operable to regulate the air/oil mixture flow,
with oil
injection into the mixture being provided intermittently, at preferred flow
rates as
follows:
Backing bearing outside Oil flow rate
diameter Lubrication/Bearing
D Oil
mm cm3/h
120 0.9to1.5
160 to 165 1.5 to 2.1
220 to 225 2.1 to 3.6
260 2.4 to 3.9
300 to 300.02 3.6 to 6.0
The applicant has appreciated that the aforementioned construction permits the
operation of the Z-mill 10 with bearing lubricating fluids supplied
independently of
rolling fluids. As such, traditional rolling fluids may be used to effect
rolling of the metal
strip 12 at conventional rolling rates.
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Table: Rolling fluid flow rates for Steel Strip
Backing bearing outside Rolling fluid flow rate
diameter Per bearing
D
Mm l itre/m i nute
120 5to7
160 to 165 10 to l 5
220 to 225 15 to 25
260 20to35
300 to 300,02 30 to 60
from 406 55 to 80
Figures 4 and 5 show the positioning of a series of four axially elongated
injector
guide tubes 86a,86b,86c,86d downstream from the needle valve assembly 84
within the
injector block housing 82.
The four injector guide tubes 86 are each fluidically coupled to the air/oil
supply
lines 78 by way of the needle valve assembly 84, so as to be independently
supplied with
the air/oil lubricant under a positive supply pressure. Most preferably, the
oil pressure
from the source 74 supplies oil to the valve assembly 84 at a supply pressure
selected at
less than about 700 psi, and most preferably about 400 and 600 psi. The valve
assembly
84 includes two injectors (not shown) communicating with each tube 86 for
enhanced
redundancy in supplying the lubricating oil droplets thereto. Each injector
tube 86 is
formed as a cylindrical tube having a radial diameter of between about I and 4
cm, and
an axial length of between about 3 and 10 cm. The relatively larger diameter
of the
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injector tubes 86 assists in the formation of discrete oil droplets within the
air/oil
lubricant mixture.
The thrust bearing assembly 80 includes a cylindrical bearing plate 90 which
extends in an axial direction along a plate axis AP-AP (Figure 4). Figure 5
shows the
bearing plate 90 as being slidably received within a downstream end of the
injector block
housing 82 so as to be reciprocally movable relative to the housing 82 in the
direction of
axis AP-AP. A retaining ring 92 is provided to limit the forward movement of
the bearing
plate 90 outwardly from the injector block housing 82. The bearing plate 90 is
formed
with four internal chambers 94a,94b,94c,94d (Figures 4 and 6) having a
cylindrical
profile and alignment which is selected complementary in shape and position of
each
respective injector tube 82. The chambers 94 have an axial length selected
preferably
greater than that of the injector tubes 86, so as otherwise not to interfere
with the axial
sliding movement of the bearing plate 90 in the direction of axis AP-AP
relative thereto.
Figure 5 illustrates best the injector tubes 86 as being open to and in fluid
communication with a respective chamber 94 allowing the substantially
unhindered flow
of the air/oil lubricant therein.
In the view shown in Figure 5, the thrust bearing assembly 80 is illustrated
best
as having an axial-most bearing surface 96 which extends normal to the plate
axis AP-AP.
One or more helical compression springs 95 (Figure 6) are provided to
resiliently bias
the bearing plate 90 axially forward, to move the bearing surface 96 towards
juxtaposed
engagement with the end 45 of the backing shaft 46.
A lubricant outlet port 98 is formed in the bearing surface 96. The outlet
port 98
consists of four separate arrays of feed openings l 00a, l 00b, l 00c, l 00d.
Each of the
arrays 100 consists of three circular openings or feed holes having a diameter
selected at
between about I and 3 mm. The feed holes of each array I 00a, I 00b, I 00c, I
00d
preferably each communicate directly through the bearing surface 96 with a
respective
chamber 94. Most preferably, the feed holes of each array 100 are arranged so
as to
extend at least generally in a radial direction about the plate axis AP-AP.
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The feed opening arrays 100a,100b are spaced respectively a radial distance d,
(Figure 8) on opposing sides of the plate axis AP-AP, and which generally
corresponds to
the distance DI, the radial inlet openings 62a,62b are spaced from the shaft
axis AS-As
(Figure 7). Similarly, the feed opening arrays 100c,100d are provided at
spaced
locations about the plate axis AP-Ap at about a 90 offset from the feed
opening arrays
100a,100b. The arrays 100c,100d are spaced from the plate axis AP-AP by a
radial
distance d2 (Figure 8) generally corresponding to the distance D2 of the inlet
openings
62c,62d spacing from the shaft axis As-As. In this configuration, the
applicant has
appreciated that as the first end 45 of the backing shaft 46 moves along its
elliptical path,
at least two feed holes of at least one or more different outlet arrays
1 OOa, l 00b,1 OOc, l 00d, are maintained in fluid communication with each of
the inlet
openings 62a,62b,62c,62d at all times. As a result, lubricating fluid is
supplied along the
feed channels 60 and from the outlet orifices with a downstream pressure to
the roller
bearings 44a,44b,44c,44d selected at less than about 50 psi, and most
preferably between
about 2 and 30 psi.
The bearing plate 90 of the thrust bearing assembly 80 furthermore includes a
resiliently compressible rubber 0-ring 110. The 0-ring 110 extends radially
about the
feed opening arrays 100a,100b,100c,100d and plate axis AP-AP. The rubber 0-
ring I 10
is sized and positioned for mated engagement with the smooth seating surface
65 formed
in the first end 45 of the backing shaft 46. In this manner the bearing plate
90 may be
secured against rotation within the mill housing 22 while being rotatably
engaged by the
backing shaft 46. Because the seating surface 65 of the shaft end 45 extends
radially a
distance greater than the path of eccentric movement of the shaft 46, the 0-
ring 1 10 is
maintained in sealing contact thereagainst, even while the shaft end 45 slides
vertically
relative thereto.
In assembly, the backing shaft 46 and lubricant supply assembly 42, are
positioned in the housing 22. The lubricant supply assembly 46 is oriented
with the plate
axis AP-AP parallel to the shaft axis As-As and generally aligned with the
centre of the
elliptical path along which the first end 45 of the backing shaft 46 moves.
The supply
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assembly 46 is positioned such that the bearing plate 90 is in juxtaposed
contact with the
shaft first end 45, and with the biasing springs 95 under partial compression.
In this
configuration, the springs 95 resiliently urge the bearing plate 90 forwardly
towards
contact against the shaft end 45, ensuring fluid sealing contact between the 0-
ring 110
and seating surface 65.
Figures 6 to 11 illustrate the positioning of the inlet openings 62 relative
to the
feed hole arrays 100 as the backing shaft 46 is eccentrically rotated relative
to the
bearing plate 90. As the backing shaft 46 moves, each of the radially
extending inlet
openings 62a,62b,62c,62d are maintained in alignment and fluid communication
with at
least two feed openings of one or more of the arrays 1 OOa, l 00b, l 00c, l
00c. The
applicant has appreciated that this redundancy ensures that bearing lubricant
continues to
be supplied to each feed channel 60a,60b,60c,60d in the event one of the feed
openings
may become blocked or inoperable. With the present construction, the air/oil
lubricant is
therefore continuously fed from the supplies 74,76 via the valve assembly 84,
tubes 86
and chambers 94 outwardly from the arrays 100 and into the lubricant feed
channels 60
as the Z-mill 10 operates.
Because the present invention uses an air/oil droplet mixture as a bearing
lubricant, as contrasted with low viscosity oils or water/oil emulsions used
for rolling
fluids, the present system allows the operation of a Z-mill 10 with
significantly lower
volumes of roller bearing lubricants than compared to conventional systems. In
normal
operations, it is envisioned that the present system would therefore use
approximately
one gallon of bearing lubricating oil per day on an all or significant loss
basis. Although
not essential, it is most preferable to select a bearing lubricant oil which
is compatible
with the rolling fluid, in the event of contamination therewith.
In use of a Z-mill 10 incorporating one or more backing assemblies 40, the
rolling of metal strip 12 is performed by work rolls 14 in a conventional
manner. During
sheet rolling, low viscosity rolling fluid is sprayed via nozzles 29 (Figure
1) onto the
surfaces of the sheet 12 as it travels back and forth between the work rolls
14.
Concurrently, the air/oil lubricant mixture is fed from the air and oil
reservoirs 72,74 via
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the lubricant supply manifold 76 into the lubricant feed channels 60 via the
tubes 86,
chambers 94 and arrays 100. Most preferably, the air/oil mixture is fed into
each
lubricant feed channel 60a,60b,60c,60d under a pressure of about 2 and 6 psi
so as to
flow outwardly into the radial grooves 70 formed about each bearing mounting
surface
48a,48b,48c,48d.
Although the preferred embodiment of the invention illustrates the bearing
plate
90 as including arrays 100 of individual feed holes as supplying lubricating
fluid to the
channel inlet openings 60, the invention is not so limited. It is to be
appreciated that the
bearing plate 90 could be provided with a lubricant feed port having a variety
of different
configurations and/or shapes. These would include, without restriction, a
single or
multiple elongated and/or oval lubricant ports, or alternately as lubricant
outlet holes of
equal or different sizes in a selected arrangement.
Although the preferred embodiment illustrates the lubricant feed channels 60
as
including a three port outlet orifice 64, the applicant has appreciated that
while the
redundancy of the outlet port construction advantageously minimizes the
possibility of
blockage, other lubricant outlet constructions may also be used.
While the preferred embodiment describes the preferred roller bearing
lubricant
as including high viscosity oils having a viscosity of about ISO 100 VG, other
low
viscosity oils with viscosities of less than about ISO 20 VG may also be used.
In addition, although Figures 7 to 12 illustrate the construction of the
manifold
bearing plate ports whereby at least two feed holes are provided in continuous
connection with each channel inlet for redundancy in the event of blockage,
the invention
is not so limited. In an alternate simplified construction, the arrays 100 may
include
outlets formed as elongated grooves or as enlarged diameter circular openings
configured, to substantially maintain fluid contact with at least one fluid
infeed channel
inlet as the backing shaft is rotated.
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Although the preferred embodiment of the invention illustrates the backing
assembly 40 of Figure 3 as including four roller bearings 44a,44b,44c,44d, it
is to be
appreciated that the present invention could equally be constructed with
either a fewer or
greater number of roller bearings 44, with a corresponding decrease or
increase in the
number of lubricant feed channels 60 being formed through the shaft 42.
Although the detailed description describes and illustrates various preferred
embodiments, the invention is not so limited. Many modifications and
variations will
now occur to persons skilled in the art. For a definition of the invention,
reference may
be had to the appended claims.
