Patent Application
20150240877
The present application claims priority to Italian Patent Application No. MI2013A000287 filed Feb. 27, 2013.
Not Applicable.
1. Field of the Invention
The present invention relates to a load damping system, applicable to sliding block adapters used for the transmission of motion generated by a motor connected thereto. Such a system finds application, for example, in the transmission of motion from the motors to the rolls of a rolling stand for flat products. In particular, the present invention relates to an elastic junction for the dynamic connection between the motor side and the adapter head, or between adapter and rolling rolls, such as to ensure the reduction of the axial tensions that are transmitted along the adapter in response to stresses generated during rolling.
2. Background Art
Two types of sliding block adapters are known in the art: fixed adapters and telescopic adapters. The first ones form a rigid body, while the latter have the possibility to vary the axial extension thereof. In the exemplary case of a rolling plant, this second solution allows shifting the rolls or rolling cylinders. Disadvantageously, both types of adapters, and in particular fixed adapters, transmit the axial component of the load, that is generated during the rolling, to the motor. The rolling stand, for example, can in fact generate axial loads due to various phenomena related to the rolling process, which through the adapters can be transmitted from the rolling cylinders to the motor. The ends of the working rolls of the stand, on the side opposite that of the adapters, are accommodated in a chock. Between the chock and the relative fixed shoulder there is a predetermined clearance which, by design, normally has a nominal value of about 1 mm, while it can actually also reach 3-4 mm, being the result of a sum of tolerances and also due to possible wear that may occur over time.
The thrust bearings of the motors generally have an axial clearance limited to ±0.35 mm for reasons of intrinsic functioning of the motors which, therefore, can be still affected by the axial loads generated by the rolling stand since the axial clearance between chocks and shoulders is greater than that of the thrust bearing of the motor.
Thus, the axial forces which develop during the rolling make such a clearance closed, and such forces are then transmitted to the motors through the adapters. These loads are harmful to the motors, which precisely to oppose such stresses are normally provided with radial or axial thrust bearings suitably sized according to the maximum load, since any failure of said bearings would entail putting the motor out of order.
In plants having this size and these features, such as rolling plants, the main motors are absolutely vital for production, and it is therefore essential to prevent failure of these members, which could lead to a shutdown of months also due to the fact that often spare parts are not available in a short time for components of this type and size (these are motors whose power can reach up to 10,000 kW). A plant shutdown is obviously the most negative factor which a producer can experience, as it involves a loss of productivity. Therefore, in order to prevent this from occurring, it is preferred to oversize the axial bearing of the motor, even if this implies a substantial increase in the size of the total expenditure: both radial and axial motor bearings are very expensive and their size consistently impacts the total cost of motors. In the prior art, the junctions between the sliding block adapters and the flanges on the roll side or on the motor side essentially consist of axially rigid systems that, due to such a rigidity, transmit all the loads from the rolling stand to the motor. That is, the adapter junctions are generally obtained by rigidly constraining the constituting parts.
A first example of this type of system is provided by document U.S. Pat. No. 7,582,019B2 in which two sections of an adapter are interconnected through a system of compensation of the axial loads which provides for the use of longitudinal cylindrical dampers arranged both within the connection itself and outside of it. The inner cylinders consist of a guiding jacket within which a sliding damper element can move, whose rectilinear motion takes place along the longitudinal axis of the adapter. This frictional non-rotatable connection is coupled to the outer cylindrical dampers which absorb the axial forces and prevent the twisting of the two interconnected segments of the adapter. In this way, however, this double connection has a rigidity that prevents the effective absorption of the transverse and torsion stresses that normally affect the normal operation of the adapters. This gives the system a lack of elasticity precisely where the greatest stresses coming from the rolling system are formed.
A second axially rigid interconnection system is described in document U.S. Pat. No. 7,784,380. The system involves the use of an interconnection between a flange and the head of an adapter consisting of a housing block rigidly fixed to the end of the adapter and within which a pressure bar is longitudinally arranged. The orientation and the shape of the bar are aimed to withstand and balance the axial thrust and traction loads, while its angular movement is limited by the design degree of freedom of the housing block. Also this solution is therefore affected by the transverse rigidity and torsion rigidity which do not allow the elastic absorption of all the tensions and stresses to which the adapter head is subjected.
In both cases described above, as in every other solution currently adopted in the prior art, a component which is essential for the effective reduction of the loads transmitted to the adapter is therefore lacking, i.e. the elastic and pluridirectional response to such loads, which may effectively reduce any risk for the integrity of the connection junctions and, in particular, of the motors.
The object of the present invention is to provide an elastic junction for sliding block adapters which allows effectively compensating and absorbing the forces transmitted by the rolling system to the motors.
A further object of the present invention is to provide a junction for sliding block adapters which allows only a certain predefined maximum force to be axially transmitted to the motors.
Another object of the present invention is to provide a junction for sliding block adapters which allows the use of a smaller axial bearing compared to those currently adopted. The present invention allows the above objects to be achieved by mans of a connection junction of an adapter to a flange for controlling the axial loads which, according to claim 1, comprises a central pin arranged perpendicular to the longitudinal axis of the adapter; multiple sliding blocks slidingly connected by means of the central pin to the adapter; a block fixed to the flange and at least two complementary and interfaced series of dampers connected to the central pin.
According to a further aspect of the invention, a rolling plant is provided which, according to claim 8, comprises at least one motor, at least one adapter for transmitting the motor motion to rolls of a rolling stand, the above said elastic junction for connecting the adapter on the motor side or on the stand side or on both the motor side and the stand side, wherein the motor and/or the rolling stand comprise a flange configured for fixing the block of the elastic junction.
The elastic junction for sliding block adapter, object of the present invention, allows the control of the axial loads resulting from the operation of the rolling plant and the transmission to the corresponding motor of only a certain well-defined and controllable load, which is by far lower than the load that would be transmitted by other currently known solutions, up to nearly completely eliminating the same load.
The device, object of the present invention, in fact uses the adapter as an elastic member having the features of a spring which acts in the axial direction and which therefore transmits known and well definable loads.
The introduction of an elastic element, comparing it to a spring characterized by an elastic constant k, allows the axial loads that reach the motor to be fixed at a certain value equal to Δx*k, where Δx is the clearance between chock and shoulder.
It is therefore possible to size the axial bearing of the motor on this force and not on the entire axial force F which may develop during rolling.
The dependent claims describe preferred embodiments of the invention.
Further features and advantages of the invention will appear more clearly from the detailed description of a preferred, but not exclusive, embodiment of a connection junction of an adapter to a flange, shown by way of a non-limiting example with the aid of the accompanying drawings, in which:
a shows a longitudinal section view of a junction according to the present invention for the interconnection of an adapter with the flange of a motor;
b shows a section view along a plane A-A of the elastic junction in
c shows an exploded view of an enlarged detail of the flange with joint for block and relative fixing points;
The same reference numerals in the figures identify the same elements or components.
As shown in
a block 1 which includes
sliding blocks 4 connected by means of the pin 5 to the adapter 3, where said sliding blocks 4 have sliding surfaces on corresponding complementary shape surfaces of the flange 2.
In
Block 1 is provided with spring packs 6 positioned on both sides so as to act in both directions. Block 1 is mounted in the flange 2 with which the adapter 3 must couple and, finally, the adapter 3 is made integral with block 1 by means of the pin 5.
Sliding blocks 4 are then connected by means of the pin 5 to the flange 2 and to the adapter 3 and allow the torque to be transmitted from the first one (flange) to the second one (adapter).
The axial stresses coming for example from the rolling cylinders are transmitted to adapter 3, to pin 5, and thus to block 1. The spring packs 6 inside block 1 are thus compressed on one side and correspondingly elongated on the opposite side, allowing flange 2 to remain stationary at a respective translation of adapter 3, pin 5 and sliding blocks 4. The device is bidirectional, i.e. it intervenes both in case of tensile forces and of thrust forces on adapter 3.
Sliding blocks 4, constrained to pin 5, are then made to translate axially as a result of a force produced for example in the rolling stand; however, they are in contact with flange 2 and, in order to have this relative movement between sliding blocks 4 and flange 2, it is necessary to overcome the friction forces which develop between the two elements as a result of the torque transmitted by flange 2 to adapter 3 by means of sliding blocks 4. This ensures that the device, object of the invention, is only activated when necessary: that is, it is activated only when the loads involved exceed the frictional forces between flange 2 and sliding blocks 4.
b shows a section along plane A-A of the elastic junction shown in
According to the present invention, block 1 is configured for the connection between adapter 3 and flange 2 of a motor block or, distally from the motor on the opposite end of adapter 3, between adapter 3 and the rolls of a rolling stand.
The invention also provides for the alternative of combining both coupling possibilities (
Block 1 also comprises one or more fixing means for fixing the block to flange 2 or to the rolls of the rolling stand.
In order to anchor the pin to the adapter head, pin 5 comprises two connecting ends 5a, 5b which protrude outside sliding blocks 4. Such connecting ends 5a, 5b can have a sectional diameter greater than the remaining pin body and are provided with joints for their fixing to adapter 3.
The junction for sliding block adapters of the present invention has the major advantages when used in rolling plants in which the adapters are used for the transmission of motion from the motor to the rolls of a rolling stand, as schematically shown in
In this specific plant configuration, the axis of adapters 3 is tilted with respect to the longitudinal axis of flange 2 by an angle a which can be between 0 and 15 degrees, thus allowing a degree of freedom such that any axial load, either transverse load or angular torsion load, can be effectively counterbalanced without damaging the motor side on one end and/or the roll side on the other end.
Such elastic and, at the same time, articulated movement of the adapters is in fact ensured by the position of pin 5 which, for each position taken, is always perpendicular to the longitudinal axis of the adapters. Moreover, the
A possible configuration of the components constituting the object of the present invention is shown in
With the aid of the device object of the present invention, the loads exerted on the adapters are not transmitted to the motor in their entirety: it has been seen that they can be reduced more than 50% compared to the solutions previously adopted, up to be almost completely eliminated.
