Note: Descriptions are shown in the official language in which they were submitted.
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This invention relates to a base s~ructure for supporting a gear
box, in particular for the rolls of a crossed-stand type rolling mill ~or
ex~mple, for the p~oduction o~ seamless tubes.
More particularly, the present invention relates to a base structure
in ~Yhich two abutment ~alls constitute a receiving and suppor-ting seat for a
gear box, the walls being perpendicular to each other, inclined at ~5 to
the vertical, and converging downwardly.
In a rolling mill of the a~oresaid type, the rolling stands are
oppositely inclined a~ 45 to the horizontal rolling axis, the axes of the
rolls of each stand also being inclined at 45.
As is known, ~he rolls of each stand are rotated by the same
motor through a single gear box to which they are kinematically connected
through respective extension shafts. Due to the inclined position of the
stands and of the rolls, the extension shafts and the axes of the gears and
wheels of the gear box are also inclined at ~5 to the vertical.
As is also well known, a gear box of the type under consideration
has considerable dimensions and a weight of the order of 100 tons, and is
generally fixed to an associated support base of appropriate structure and
dimensions. The most distinctive part of such a base is constituted by a pair of
mutually-perpendicular abutment walls which are inclined at 45 to the
vertical, converge downwardly and constitute the receiving seat for the gear
box. Generally, in a crossed-stand type rolling mill the gear boxes are
supported at a level of 5 to 7 metres or more beneath the factory floor.
Even for gear boxes, as for all cornponents of a rolllng mill, there are
periodic planned maintenance and checking operations with possible
replacement of parts and components which are worn or not entirely reliable.
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One method of carrying out sucil operations involvcs a progressive
opening of the casing of the gear box with related dlsmantling operations and
removal o$ the gears of the gear box which are accessible from the cxterior.
The same operations, but reversed in sequence, are then carried out to re-
assemble the components of the gear box. Since these components, taken
individually, are not generally more than 20 tons in weight, the said method
may be carried out by using the same crane used for lifting and replacing the
components of the rolling s~ands, these components as is well known having a
weight of from 25 to 30 tons. However as well as this known advantage there
is the inconvenience resulting from the considerable handling difficulty
caused by the weight of the individual components of the gear box and of the
need to position them inclined to the vertical. Indeed, the dismantling and
reassembly of these components involves a whole series of highly exacting
manoeuvres which involve a considerable amount of time as well as a high risk
of the various components of the gear box knocking against each other with
the possibility of deformation or even breakage thereof.
In order to overcome these disadvantages and in accordance with
another method, the entire gear box is raised to the level of the factory floor
where it is positioned with its axes horizontal. After the opening of the casing
of the gear box, the removal and/or replacement of the components may be carried
out more easily. Although advantageous from the point of view of speed and
facility of execution, this method requires the use of a 100 ton crane, a
crane which, in rolling mills, is used solely for raising the gear boxes when
the said maintenance and check operations are required and which, notwith-
standing the long periods during which this crane is not required, necessitate
the housing of the rolling mill in a suitablc shed of very large dimensions.
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The main ob~ect of this invention is to overcome the
disadvantages mentioned above with reference to the known art.
According to the presen-t invention there is provided a
base structure for supportiny a gear box in an inclined position,
said gear box being oE the type inclucling a casing and components
removably mounted therein, said base structure being arranged to
support the gear box in an inclined position and enabling the
gear box to be rotated out of this position for maintenance or
repair; said base structure comprising: two abutment walls
angled relative to each other and converging downwardly, said walls
serving to support the gear box casing in its said lnclined
position, a pivot structure supported close to the uppermost
edge of one of the said abutment walls, said pivot structure
defining a horizontal pivot axis and being rotatably engageable
by the gear box casing along a corner edge thereof whereby to
enable the gear box to be swung up out of its inclined position
by rotation about said pivot axis, a horizontal pivot supported
close to the lowermost edge of the other said abutment wall, and
a strut having one end rotatably mounted on said horizontal pivot,
the other end of the strut being intended to engage the underside
of the gear box casing after the latter has been swung out of its
inclined position whereby to support the casing in a position
facilitating its maintenance or repair.
According to another feature the present invention
proviaes a crossed~s-tand rolling mill having rolls inclined at
to the horizontal, and drive means for rotatabl~ driving
said rolls, said drive means including gear boxes of the type
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comprising a casing and components remov~bl~ mowlted the~ein,
each said gear box being supported by a base structure according
to Claim 1, to enable the gear box to be moved from an inclined
operating position, to a horizontal position facilitating
maintenance and repair, by pivoting of the gear bo~ casing
about said horizontal axis defined by the said pivot structure.
Further characteristics and advantages will be better
understood from the description given below of one embodiment
of a gear box base structure according to the invention, reference
being made to the appended drawings, given purely by way of
non-limiting example, in which:
Figure 1 is a schematic view of a cross-stand rolling mill
in which the gear boxes are supported by respective bases according
to the invention;
Figure 2 is a side view on an enlarged scale of a base
structure according to the invention;
Figure 3 is a plan view of a detail of Figure l;
Figure 4 shows to an enlarged scale, a detail of the base
of the preceding Figures.
With reference to Figure 1, two stands of a crossed-stand
type rolling mill are indicated schematically by 1 or 2, the
stands, as known, being oppositely inclined at 45 to the
horizontal rolling axis indicated A.
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Each stand operatively supports ~wo roll5 3, ~ al50 incl:ined at
45 to the axis A, which are driven by a motor 5 through a singl~ gear box 6
to which the rolls 3, 4 are kin~matically connected ~hrough extension shafts
7, 8.
This gear box 6, the casing of which is specific~lly indicated 9,
is fixed to a support base 10 having two bearing wa]ls respectively indicated
11 and 12 these walls being perpendicular to each other and converging
down~ardly. ~le wall 12 extends parallel to the axis of the rolls 3, 4 of
the corresponding stand 1.
The walls ll and 12 are generally constituted by plates fixed in
the desired angled positions on respective supports 13, 14 generally of a
s~bstantial metal structure.
Close to its uppermost edge the support 14 carries, on respective
lugs 15, 16, horizontal, coaxial pivots 17, 18 which extend parallel to the
rolling axis A. The casing 9 of the gear box 6 is pivoted along a corner edge
on these pivots 17, 18. Purely by way o~ example, the pivoting is preferably
achieved by means of a pair of saddles 19, 20 which are fixed to the wall of
the casing 9 facing towards the corresponding rolling stand 1 and are
rotatably mounted on the said pivots.
By 21 is generally indicated a strut having one end rotatably
mounted on a horizontal pin 22 parallel to the rolling axis A and carried by
the support 13 by l~holly conventional means schematically shown at 23. The
strut 21 is preferably constituted by a pair of parallel arms 21a, 21b the
free ends of which support an idler roller 2~. By means of this roller 24
the s~rut 21 is intended to releasably engage a hook yrojection 25 formed or
otherwise fixed to a central portion of the casing 9 of the gear box, close
to the lower co-rner thereof opposite that pivoted on the pivots 17, 18,
mentioned above.
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A further hook projection 26 is formed or otherwise fixed to the
casing 9 in a position thereon which lies as far as possible from the axis
of the pivots 17, 18 when the gear box 6 is in its operative posi~ion fixed
to the bearing walls 11, 12.
Purthermore, the hook portion ~6 is in a position accessible from
above since it is intended to be engaged by a crane the lifting hook of which
is shown schematically at 27 in the drawings.
~ hen it is necessary to carry out an operation on the gear box 6,
for example to remove and/or replace components of the gear box, one proceeds
in the following manner.
After releasing the casing 9 from the bearing walls 11, 12,
uncoupling the gear box 6 from the motor 5 and from the extension shafts 7,
8, the hook 27 of the lifting crane is engaged with the hook projection 26
of the casing. Thereafter, the entire gear box is displaced angularly
about the axis of the pivots 17, 18 until it takes up a position in which
the axes of its gears and other similar components are horizontal. Once
this position has been reached, the strut 21 is operated ~either manually or
by means of conventional motors) to engage the idler roller 24 thereof in the
hook projection 25 of the casing 9. ~ith the gear box 6 firmly held in
position with its axes hori~ontal, the operations of removing and replacing
components of the gear box itself may now be carried out rapidly and easily.
Added to this indisputable technical advantage is that constituted by the fact
that the displacement of the gear box about the axis of the pivots 17 and 18
may be carried out by using the same crane as that already used for the
replacement and displacement of the actual rolling components.
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Obviously all the reverse opera-tions for re-positioning the gear
box in the seat formed by the support base of the invention may also be
carried out very rapidly and saf~ly.
