Device for raising and withdrawing a back-up roll bearing unit

The invention relates to a device for raising and withdrawing a bearing unit of a back-up roll of a roll stand. Said bearing unit is comprised of a piece to be inserted inside which has a roll pin bearing arranged therein. According to the invention, a change-over device is configured so that it can be temporarily coupled to the bearing unit and is provided for effecting an axial movement toward and away from the back-up roll.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a device for mounting and demounting a bearing unit, comprised of a chock with a roll pin bearing arranged therein in connection with a back-up roll of a roll stand.

2. Description of the Related Art

It is known to arrange the back-up rolls of roll stands in such a bearing unit, for example, a Morgoil bearing. These have a hydraulic removal device installed within the chock for mounting and demounting the bearing onto and from the roll pin. Of these hydraulic removal devices, remaining at all times in each bearing unit, there must therefore be, for example, in a seven stand rolling train, a total of 28 such units because each back-up roll has on the movable as well as on the stationary bearing side a bearing unit, respectively. In addition to this, at least the same amount of space is required for additional change-over locations, and, moreover, a significant proportion of spare parts is required because they are cost-intensive specialty parts which have a long delivery time. As a result of the constant residence in the bearing unit, the hydraulic removal devices are also subject to external influences within the bearing, such as contaminated oil, bearing damage, and start-ups which reduce the service life and/or require repair work.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide a device with which the described disadvantages for back-up roll bearings can be avoided, which, in particular, reduces the expenditure of the bearing change, and which can be used variably.

This object is solved according to the invention by a change-over device which can be temporarily coupled to the bearing unit and is configured for generating an axial movement in the direction toward the back-up roll and away from it. By accordingly providing, on the one hand, a separate change-over device, i.e., a change-over device independent of the bearing unit, which, on the other hand, can be universally used for mounting as well as demounting the bearing unit, one change-over device is sufficient in order to mount or demount the bearing units; only when both bearing units of a back-up roll are to be changed at the same time, a second such change-over device is required. In no case, however, is it required any longer to provide each back-up roll of a roll stand with an integrated hydraulic removal device, as in the prior art. Aside from the fact that the change-over device is no longer exposed to the effects of the rolling operation, a simpler and lighter configuration results for the bearing units. The change-over device can advantageously be used in the bearing and roll shop, and it is only required to couple the device with the bearing unit to be demounted or newly installed in order to mount or demount with, if desired, a single change-over device all bearing units onto or from the respective back-up rolls.

According to one proposal of the invention, the change-over device has lever-like inner claws and lever-like outer claws, wherein the inner claws engage a pin end of the back-up rolls and the outer claws engage the bearing unit. The claws in this case provide the coupling means and serve at the same time for introducing the axial movement in order to push the bearing unit onto the roll pin or to remove it therefrom. Instead of a coupling via claws, the change-over device could also, for example, be coupled by a screw connection to the bearing unit.

In a further embodiment of the invention, the inner and outer claws are rotatable and can be locked like a bayonet closure in the pin end or in the bearing unit. After attaching or inserting the change-over device, the inner and outer claws must thus be rotated only by approximately 45° in order to ensure the locking action.

According to a preferred embodiment of the invention, the pin end and an intermediate ring, screwed externally onto the bearing unit, are cloverleaf-shaped, with through grooves for the inner and outer claws, and the claws have correlated therewith in situ, after rotation into an engagement position, complementary locking projections of the pin end or the intermediate ring, wherein, moreover, a pressure ring, connected in front of the roller pin bearing, is positioned opposite the outer claws. In this way, it can be achieved that the axial movement, introduced into the inner claws locked fixedly in the back-up roll, is deflected during removal into an oppositely oriented movement or force direction caused by the outer claws contacting the locking projections of the intermediate ring and, accordingly, removing the entire bearing unit from the roll pin. On the other hand, the claws press, as a result of the axial movement introduced into the inner claws being reversed also during mounting, onto the pressure ring so that the entire bearing unit is pushed onto the roll pin.

Even though the axial movement could be effected mechanically or by means of an electrical drive, for example, by means of a worm gear and a toothed rack, it is suggested advantageously that the inner claws are arranged on a piston of a hydraulic cylinder that can be integrated into the change-over device. Commercially available standard cylinders can be used for this purpose, and, as a result of the inventive separation of removal device and bearing unit, oil mixing between the lubricant oil and the hydraulic oil required for the axial and rolling pin bearings cannot occur.

When preferably the free piston end facing away from the inner claws of the hydraulic cylinder is provided with a handwheel, the bayonet closure can be reached simply from the exterior, and this is possible uniformly for the entire change-over device. This requires that the through grooves for the inner and outer claws as well as the claws themselves are aligned with one another.

DETAILED DESCRIPTION OF THE EMBODIMENTS

TheFIGS. 1 and 3show only the roll pin2of a back-up roll1, respectively. According toFIG. 1, a bearing unit3is mounted on the roll pin2which comprises a chock4with a roll pin bearing or axial bearing5. An intermediate ring6is screwed onto the forward end of the bearing unit3; the ring6has a shape like a cloverleaf and has alternatingly arranged through grooves7and locking projections8(compareFIG. 2).

On the roll pin2, i.e., in the area of the roll pin end9, a pressure ring11contacting the axial bearing5and a ring nut12threaded thereon are arranged on the locking ring10. The locking ring10has also locking projections13which have correlated therewith through grooves14, illustrated in dashed lines inFIG. 2, provided on the outer circumference of the roller pin end9.

For mounting the bearing unit3in the operating position illustrated inFIG. 1, the bearing unit3is aligned and positioned exactly relative to the center of the back-up roll1. The same holds true for the locking ring10, whose locking projections13must to be aligned with the through grooves14of the roller pin end9. Subsequently, the bearing unit3is carefully pushed onto the roll pin2and, by rotation of the locking ring10, locked in the position illustrated inFIG. 2on the back-up roll1, i.e., its roll pin2. The securing segment15subsequently mounted prevents then an unwanted rotation of the locking ring10. For preparing the final mounting of the bearing unit3, the ring nut12is screwed on as far as possible.

After completion of these preparatory measures, a change-over device16is attached which has four outer claws17positioned at identical spacing from one another and four inner claws18also spaced at an identical spacing from one another. The inner claws18are correlated with through grooves19, illustrated in more detail inFIG. 2, in the roll pin end9at the end face. When inserting the change-over device16, the outer claws17thus penetrate through the through grooves9of the intermediate ring6and the inner claws18through the through grooves19, and, upon rotation by 45°, they reach their engagement position, illustrated inFIGS. 1 and 2, in which the outer claws17are locked on the intermediate ring6, i.e., its locking projections8, and the inner claws19are locked on the backup-roll1, i.e., on its roll pin end9. In the embodiment, the inner claws18are arranged on the cylinder piston20of a hydraulic cylinder21fastened on the change-over device16whose free cylinder piston end22is provided with a handwheel23. During manipulation of the change-over device16with a swinging crane, not illustrated, the handwheel23provides in a simple way the possibility to perform the locking rotation of the claws.

When the hydraulic cylinder21is now loaded with pressure in the direction of the arrow illustrated in bold face, the change-over device16, secured on the back-up roll1by means of the inner claws18, presses via its outer claws17the pressure ring11against the roll pin bearing or axial bearing5. In this way, the bearing unit3with its pin bushing24is pushed increasingly onto the cone of the roll pin2until it reaches the end position according toFIG. 1.

For securing this mounting position, the ring nut12is tightened to the dead stop. The claws17,18are then aligned with the complementary through grooves7and19so that the change-over device16can be removed. When the holding segment15is secured by screwing on the ring nut12, the ring nut is secured against detachment. As soon as the previously opened closure lid25has been pivoted into its closed position (illustrated in dash-dotted line inFIG. 1), in which it encapsulates the roll pin2, the rolling operation can be started again.

The removal process illustrated inFIG. 3is carried out in reverse, but otherwise identical, sequence of the afore described attachment of the change-over device16—which is, however, preceded by the detachment of the holding segment15from the ring nut12. By loading the cylinder piston20of the hydraulic cylinder21in the direction of the bold faced arrow, pressure is applied to the pressure ring11and the ring nut12is relieved which can then be removed so that the holding segment15(seeFIG. 1) can be removed—which, for this reason, is not illustrated inFIG. 3. By rotation of the locking ring10by 45°, the bearing unit3is unlocked. After renewed application of hydraulic pressure, the change-over device16, secured on the back-up roll1by means of the inner claws18, pulls via the outer claws17, which now contact the locking projections8of the intermediate ring6, the intermediate ring6and thus the entire bearing unit3with the pin bushing24from the cone of the roll pin2, as illustrated inFIG. 3. As soon as the pin bushing24is free, the hydraulic pressure can be switched off and the change-over device16, as described in connection with mounting according toFIG. 1, can be removed. The bearing unit with the chock4and the axial bearing5is free in order to be removed carefully from the back-up roll1.