Metallurgical apparatus – Means sealing or opening aperture in vessel – By means plugging aperture
Reexamination Certificate
1999-12-03
2001-06-12
Kastler, Scott (Department: 1742)
Metallurgical apparatus
Means sealing or opening aperture in vessel
By means plugging aperture
C266S271000
Reexamination Certificate
active
06245286
ABSTRACT:
The invention relates to a swivel device with a cantilever arm for swivelling an operational element between a home position and an operational position. Such a device is used, for example, for swivelling a tap hole plugging gun from a home position into an operational position in front of the tap hole of a blast furnace, as well as for the subsequent pressing of the plugging gun against the tap hole.
A traditional swivel device for a tap hole plugging gun comprises, in a manner known per se, a fixed supporting structure and a cantilever arm. The latter has one of its two ends mounted in a swivelling manner in the supporting structure. In most cases, hydraulic cylinders are used to swivel the cantilever arm. The swivelling range of such a swivel device should, as a rule, be as great as possible, in order to be able to swivel the plugging gun as far as possible out of the range of the tapping channel. In addition to this, it must be considered that modern plugging guns are operating with increasingly high plugging pressures. As a result, the swivel device which is intended to press the plugging gun against the tap hole must also be designed for ever greater pressing forces.
In U.S. Pat. No. 3,765,663 two different embodiments of a swivel device for a tap hole plugging gun are described. In the first embodiment, a hydraulic cylinder is arranged between a fixed lever arm on the supporting structure of the cantilever arm and the rear end of the cantilever arm. The swivelling angle is limited with this device to approximately 90°, in order to be able to achieve a sufficiently great pressure force. For extending the swivelling range beyond 90°, U.S. Pat. No. 3,765,663 proposes the arrangement of a lever system between the hydraulic cylinder and the supporting structure. This lever system consists of a U-shaped element, one end of which being secured in a jointed manner to the supporting structure, and the other end of said element being connected in a jointed manner by means of a connecting rod to the cantilever arm. The hydraulic cylinder is arranged between the supporting structure and the U-shaped element.
In order to extend the swivelling angle beyond 90°, it has been suggested to use swivel devices with several hydraulic cylinders. DE-A-2035697 discloses for example a swivel device for a tap hole plugging gun which has a main cylinder for generating the swivelling movement and a smaller ancillary cylinder for overcoming the dead centre of the main cylinder. The main cylinder is arranged between a first lever arm at the rear end of the cantilever arm and a first fixed lever, which projects from the supporting structure of the cantilever arm. The auxiliary cylinder swivels the cantilever arm beyond the dead centre of the main cylinder. A hydraulic switch alters the stroke direction of the double-acting main cylinder when the dead centre is overrun.
U.S. Pat. No. 4,544,143 discloses a swivel device for a tap hole plugging gun which has two hydraulic cylinders of equal size. The first hydraulic cylinder is mounted between a fixed point on the supporting structure of the cantilever arm and a swivel frame. This swivel frame is mounted in a swivelling manner on the supporting structure, wherein its swivel axis is co-axial to the swivel axis of the cantilever arm. The second hydraulic cylinder is arranged between the swivel frame and the rear end of the cantilever arm. The two hydraulic cylinders are actuated either simultaneously or in a specific sequence. They both contribute their share to covering the swivel range of the cantilever arm. In the operational position, the first hydraulic cylinder must transmit onto the supporting structure the moment of force exercised by the second hydraulic cylinder on the swivel frame, when pressing the plugging gun against the tap hole. As the lever arms of both hydraulic cylinders are approximately of the same size, both cylinders are designed to be of equal strength. It is likewise to be noted that the lever arm which is available to the second hydraulic cylinder for transferring its force onto the cantilever arm is not influenced by the position of the swivel frame.
It is an object of the present invention,to improve the transfer of forces in the swivel device known from U.S. Pat. No. 4,544,143.
This object is achieved by means of a swivel device according to claim
1
. Such a swivel device comprises, like the device disclosed in U.S. Pat. No. 4,544,143: a cantilever arm for supporting an operational element, a supporting structure in which the cantilever arm has one end mounted in a swivelling manner a swivel axis; a first linear drive, as a rule a hydraulic cylinder, to swivel the cantilever arm between its home position and its operational position, wherein the linear drive is connected to the cantilever arm by means of a first rotational joint; a swivel arm, which is mounted with one end in the supporting structure so as to be capable of swivelling about a swivel axis, wherein the linear drive is connected by means of a second rotational joint to the free end of the swivel arm; and an actuator drive for swivelling the swivel arm relative to the supporting structure.
According to the invention, the swivel axis of the swivel arm is not, as described in U.S. Pat. No. 4,544,143, located co-axially to the swivel axis of the cantilever arm, but at a certain distance from it. In other words, the swivel arm is mounted eccentrically to the cantilever arm. Due to this eccentric mounting of the swivel arm, it will be possible to increase the lever arm with which the linear drive exercises its force on the cantilever arm. By means of an adequate swivelling of the eccentrically-mounted swivel arm, it will also be possible to switch the actuator of the swivel arm largely free of force, when the cantilever arm is in the operational position. In other words, the swivel arm can be swivelled into a position in which the linear drive does not exercise any moment of force onto the actuator drive, when transferring its force onto the cantilever arm. When the cantilever arm is swivelled from its home position into its operational position, the hydraulic cylinder of the cantilever arm and the actuator drive of the swivel arm are actuated either simultaneously or in succession. The actuator of the swivel arm in the present invention also contributes its share to covering the swivel range of the cantilever arm. In comparison with the swivel device from U.S. Pat. No. 4,544,143, a swivel device according to the invention can, however, be more compact and cheaper, wherein neither the swivelling range nor the pressure force transferred on to the operational element need to be reduced.
In an advantageous embodiment of the invention, the swivel arm is capable of being swivelled by means of its actuator into an operational position, in which, in the operational position of the cantilever arm, the second rotational joint of the linear drive, is located in the immediate proximity of a plane, which contains the swivel axis of the swivel arm and the centre of the first rotational joint of the linear drive. In this position, the swivel arm should absorb no moment of force, or only a small moment of force, when the linear drive is actuated, so that the actuator must apply no force, or only a small force, in order to hold the swivel arm in its operational position. The actuator drive of the swivel arm can, accordingly, be designed substantially weaker than the linear drive of the cantilever arm.
In an alternative embodiment, the swivel arm can be swivelled into an operational position by its actuator drive, in which, in the operational position of the cantilever arm, the second rotational joint of the linear drive is located on the other side of a plane which contains the swivel axis of the swivel arm and the centre of the first rotational joint. In other words, the second rotational joint of the linear drive is swivelled beyond the position in which the swivel arm is free of any moment of force when the linear drive is actuated. It will be noted that during the swivelling oper
Kremer Victor
Lonardi Emile
Malivoir Philippe
Berkowitz Marvin C.
Kastler Scott
Nath Gary M.
Nath & Associates PLLC
Paul Wurth S.A.
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