Heating – Tumbler-type rotary - drum furnace – Having structure agitating or controlling the motion of the...
Reexamination Certificate
2000-01-05
2001-02-13
Ferensic, Denise L. (Department: 3749)
Heating
Tumbler-type rotary - drum furnace
Having structure agitating or controlling the motion of the...
C432S103000, C248S130000
Reexamination Certificate
active
06186778
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a device for driving a cylinder in rotation about its longitudinal axis the cylinder being such as a furnace for firing minerals. in particular a cement furnace.
BACKGROUND OF THE INVENTION
It is known that cement furnaces are large in both length and diameter and that this causes problems at the level of the furnace supports and the driving device since the furnace must be able to permanently rotate about its longitudinal axis.
The weight of the furnace, which comprises the outer metal casing, the inner refractory lining and the material being processed, is such that a bending strain of the oven is observed between the support points and even beyond. To limit the bending strain to acceptable levels, it is necessary to provide a sufficient number of supports. Dry process furnaces using preheaters are generally provided with three supports.
In addition to these permanent dynamic deformations provided for under normal operating conditions accidental events, such as local overheating or prolonged idle times, can sometimes cause exceptional deformations that are more significant in nature.
In the case of furnaces provided with three supports, these exceptional deformations can be such that when in rotation, the furnace only rests on two of the three supports, thus creating, firstly dangerous overloading in view of the mechanical strength of the supports and secondly, variations in the span (or contact surfaces) between the teeth of traditional gear drive mechanisms, a part of which is integral with the furnace while the other is fixed: this is also dangerous in terms of the mechanical performance of the systems.
With the evolution of firing processes using pre-calcinators, it has become possible to reduce the length of rotary furnaces and consider the use of only two supports: this solution has the advantage of reducing the number of mechanical parts but also of limiting the risks of a support being overloaded in the case of exceptional deformation of the furnace.
With furnaces using two supports, the problem of overloading the supports in the case of exceptional deformation is avoided but the span of the supports between the fixed roller supports and the runner surfaces which are subjected to the deformations of the furnace is no longer appropriately guaranteed due to lack of parallelism.
With furnaces using two supports, problems due to variations in the span between the teeth of traditional gear drive mechanisms are as critical as with furnaces using three supports, in the case of exceptional deformations.
To compensate for these problems it was considered, for furnaces using two supports (EP-A-0570696), to create articulated supports such that roller bearings having both driving and supporting functions could respond to deformations of the furnace. However, such a facility is complex to implement and maintain.
SUMMARY OF THE INVENTION
It is thus an object of the present invention to provide a driving device that is independent from the support surfaces and that can respond to deformations of the furnace as well as to its longitudinal movements and, more generally, to deformations of any device having the elongated shape of a cylinder or a tube, the support surfaces having no driving function but being advantageously capable of being articulated so as to respond to deformations of the furnace (or of any equivalent device).
In addition to the advantage of avoiding the use of the expensive supports mentioned above, the invention has a number of other advantages in particular those of:
reducing civil engineering work, as the driving device of the furnace no longer requires a significant foundation.
replacing the single big motor currently used with several smaller motors that are more modest, less expensive and easier to obtain,
simplifying maintenance with minimal amounts of lubricants required compared with the quantity used with gear and pinion systems
The device according to the invention for driving a cylinder in rotation about its longitudinal axis said cylinder resting on raceways permitting said rotation. is characterised in that it comprises:
a) at least one ring gear (
2
) having side faces that are substantially parallel to each other and substantially radial from (perpendicular to) the cylinder axis, said gear being substantially concentric with the cylinder and being arranged outside the cylinder and connected thereto by securing means (
3
) capable of withstanding distance variations between the cylinder and the ring gear.
b) one or more modules each comprising a rigid structure (
16
), even numbers of truncated rollers (
4
,
5
), and supports (
27
,
21
) for the truncated rollers, said truncated rollers being capable of rotating about their longitudinal axes (
6
,
7
) and being connected to their supports through ball or plain bearings, said truncated rollers having their generators (
37
,
38
) intersect substantially on the cylinder axis at a point (C) which is substantially the center of the ring gear and being arranged in facing pairs on either side of the side faces of the ring gear and being capable of pressing on said side faces, at least one of the rollers being a drive roller whose function is to transmit a driving force to the ring gear,
c) at least one actuator (
30
) for each pair of rollers, capable of exerting, through the roller supports, enough direct or indirect pressure on the rollers of said pair to firmly press said rollers against the ring gear and to enable them to drive both the ring gear and the cylinder in rotation, the actuator supports and the roller supports of each module being connected to said rigid structure, which comprises means (
22
) allowing it to move and change direction in response to the movements and direction changes experienced by the ring gear during its operation.
It is to be understood that the rollers referred to in the present description are drive rollers of the ring gear, with the exclusion of any other rollers that may be used in other parts of the facility and in particular with the exclusion of the rollers bearing the cylinder.
REFERENCES:
patent: 2819130 (1958-01-01), Kaminsky
patent: 3027553 (1962-03-01), Sandor
patent: 3966395 (1976-06-01), Schneider et al.
patent: 4030878 (1977-06-01), Kunath
patent: 4344596 (1982-08-01), Hjaeresen
patent: 5890814 (1999-04-01), Catlett
patent: 1 092 365 (1958-12-01), None
patent: 39 05 345 (1989-07-01), None
patent: 631 665 (1927-12-01), None
patent: 2 242 890 (1975-03-01), None
patent: 2 677 419 (1992-12-01), None
Ferensic Denise L.
Pennie & Edmonds LLP
TECHNIP
Wilson Gregory A.
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