EP0416717B1 - Roll stand for a planetary rolling mill - Google Patents

Description

The invention relates to a roll stand for a planetary rolling mill with stand, stationary support bodies with rolling segments, which are mounted in chocks, and are mounted in cages around the intermediate and work rolls rotating around the support bodies; see e.g. DE-C 1 140 534. In such a planetary rolling mill, the Platzer planetary rolling mill named after its developer, the work rolls are brought against the centrifugal force against the intermediate rolls and these against the supporting bodies by disc spring assemblies when circulating around the stationary supporting bodies. Except for a small area of the forming zone, the surface of the support body constitutes an exact cylinder surface. In this area of the forming zone, the rolling surface deviates from the exact circular arc shape in order to ensure a perfect, i.e. to ensure groove-free rolling surface. This roller geometry, which deviates from the exact cylinder surface, is realized for wear reasons by means of rolling segments inserted into the support body. These rolling segments, which form the rolling path for the intermediate rolls, are made of hardened steel and are interchangeably fastened in recesses in the supporting body.

The rolling segments are subjected to very high mechanical loads, because in the forming zone the radial rolling forces in the stationary support body are applied via them be directed. High Hertzian pressures occur during the forming process when the support rollers roll on the roll segment. With a number of 24 support rollers per cage, each rolling segment is rolled over 24 times with each rotation of the cage.

With a normal cage speed of 120 revolutions per minute and a load of approx. 85 t, the service life of a segment is approx. 25 hours. An incipient dimple indicates that the segment must be reground. For regrinding, the roller set must be extended from the stand so that the rolling segment can be dismantled. You have to remove five work rolls and five backup rolls from each set before you can dismantle the unwinding segments. These are fastened, for example, with screws in the support body. The old rolling segment is removed and reworked on a surface grinding machine. Another, fully ground roll segment is installed in the roller set and this is completed again with the five support and work rollers. It means a lot of work and time, i.e. a major restriction of the availability of the planetary rolling mill if the rolling segments have to be removed and reground every 25 hours.

In addition, it is still possible with smaller roll stands to remove and install the work rolls by hand, but that a light crane is already required to handle the unwinding segments. With medium and large roll stands, however, where the work rolls weigh up to 600 kg, you cannot do without the appropriate lifting equipment, which leads to increased investment costs and an extension of the and installation times.

Long downtimes are not acceptable for a production machine or system. This applies particularly to systems with a high investment volume. The aim of a roll stand must therefore be to both extend the gaps between the necessary replacement of the work rolls and the unwinding segments and to reduce the time for the replacement or conversion.

Since grinding of the work rolls in the installed state has succeeded in significantly reducing the work involved and increasing the time between changing the work rolls to around 100 hours of use, the rolling segments with a service life of approx. 25 hours are currently and cost-determining factor.

The invention has for its object to significantly increase the time intervals between changing the rolling segments and to reduce the work involved.

This object is achieved in a roll stand of the type described in the introduction by the characterizing features of claims 1 and 2. With a roll stand designed in this way, the very time-consuming steps required to remove worn-out rolling segments and installing regrinded rolling segments, which are usually necessary every 25 hours, are no longer necessary.

These steps are: Extending the two support bodies from the roll stand, removing 5 work rolls and 5 intermediate rolls each, changing the rolling segments and reinstalling them in reverse order.

In a rolling stand according to the invention, the rolling segments currently in use are so worn out after approximately 25 hours of operation, even with optimal heat treatment, that they have to be replaced. However, since the support body is now equipped with 4 rolling segments evenly distributed over the circumference, the support bodies are simply extended out of the roll stand, rotated through 90 ° and reinstalled. In this way, the next of the four rolling segments comes into the working position. As the service life of the work rolls until the necessary regrinding is approx. 6 hours, rotating the support body coincides with every fourth regrinding of the work rolls. This means that no separate removal and installation is necessary for rotating the support bodies, since they are only rotated through 90 ° and reinstalled every fourth grinding of the work rolls, if they have to be removed anyway.

The arrangement of 4 rolling segments per support body, which are used one after the other, results in a further advantage. There is also no need to remove and install 5 work rolls and 5 intermediate rolls, which is usually necessary to change the unwinding segments, since this operation can be carried out precisely when the work rolls are finally used up after 16 regrindings, i.e. have reached the smallest permitted diameter and must be replaced by new ones.

In previously built Platzer mill stands, the work rolls are pressed against the intermediate rolls against the centrifugal force by means of plate spring packets while rotating around the support bodies, and these are kept in constant contact with the cylindrical surface of the support bodies. In the area of the rolling segment with its geometry deviating from an exact cylinder surface, the rollers are pressed on by the rolling force. In the roll stand according to the invention, at the usual speeds in the region of the three additional rolling segments, due to the geometry, the intermediate rolls would briefly lift off and then be put back on the support body surface in an abrupt manner and thus lead to wear. In the invention, provision is therefore made by a constructive measure that the lifting of the rollers when rolling over the three non-engaged rolling segments is reliably avoided. Two rolling rings are suitable for this, one on each side of the support body. By means of these rolling rings, the intermediate rolls are also guided on a perfect circular path in the region of the three rolling segments which are not in engagement, so that a jerky placement of the intermediate rolls is avoided. In the work area, the rolling rings have recesses so that the rollers can rest on the flattening of the rolling segments.

The chocks have a square basic shape, with the help of which the exact positioning of the rolling segments, each offset by 90 °, is achieved.

The advantage of the rolling stand according to the invention is that the active rolling segments only after one Operating time of approx. 100 hours must be replaced, and that when the work rolls are replaced or regrind at this point anyway, the next pair of rolling segments is brought into the working position by installing the support body rotated through 90 °. The removal and installation of the rolling segments is no longer necessary, as is the removal and reinstallation of 5 work rolls and 5 intermediate rolls. It is also achieved that the 4 pairs of worn rolling segments are replaced when the work rolls have to be replaced, so that no additional work and assembly work is required.

An alternative embodiment of the invention is that the chocks are octagonal and each support body has eight rolling segments. This has the advantage that the time span between the necessary replacement of the rolling segments can be doubled again.

An advantageous development of the invention consists in that the two rolling rings of a support body can be rotated relative to the support body by a rotating device and can be braced against the support body by clamping devices. This makes it possible to turn the rolling rings relative to the support body by 90 ° or 45 ° in a simple and quick manner. This rotation is necessary so that the cut-outs of the rolling rings match the processing zone again. With these devices, the rolling rings are rotated without disassembly and assembly work and under the pressure of the disc spring packets. In order to turn the rolling rings, are arranged between the rolling segments (preferably the four) solved, with the help of which the rings are clamped against the support body during operation.

The two rolling rings of each support body are expediently rotated synchronously by the required 90 ° or 45 °. For this purpose, it is provided that the rolling rings on the side facing the support body are provided with an internal toothing. Drive pinions engage in this internal toothing and are mounted on a common shaft that runs in a bore in the support body and is rotatably mounted therein. The drive takes place by means of a drive unit with a stepper motor arranged in one of the chocks, so that an exact positioning in the installed state can be carried out without measuring and regulating device and without visual inspection. In order to keep the size of the stepper motor small, a hydraulic reinforcement and a self-locking gear are arranged between it and the pinion. This self-locking gear (eg a worm gear) has the advantage that it reliably prevents shaking in the operating state, ie a gradual overcoming of the clamping force of the clamping device.
The clamping devices are advantageously designed as clamping cylinders which are arranged in bores in the support body. The clamping force is generated by disc springs, the loosening for turning the rolling rings is done by pressurizing the cylinder space. The free end of the piston rod has a head or a slot nut which engages in an annular groove of the rolling segment, which is incorporated on the surface facing the support body. When the cylinder is relieved, the spring force of the disc spring pulls the Roll-off ring firmly against the support body.

In order to make the installation and removal of the support bodies with their chocks as simple as possible, the edge lengths or the distance between the side surfaces of the latter are smaller than the outer diameter of the planetary gear set. Two strips are provided for each chock, which are screwed onto the vertical side surfaces of the chocks according to the installation position and are mounted accordingly when the support body is turned by 90 ° or 45 °. This is the only manual action when rotating the support body.

In order to facilitate the respective rotation of the support bodies, they can be equipped with pivot pins at each end, which protrude beyond the chocks. This means that the support body can be rotated by 90 ° or after the planetary roller has moved out of the stand. 45 ° in a rotating device standing next to the roll stand.

Fig. 1

einen Querschnitt durch den oberen Stützkörper

Fig. 2

einen Abrollring

Fig. 3

einen Längsschnitt durch einen Stützkörper mit Abrollringen, Dreh- und Klemmeinrichtung

Fig. 4

einen Klemmzylinder mit Tellerfeder

Fig. 5

die Anordnung der Antriebswelle

Fig. 6

eine Antriebseinheit

The invention is illustrated with the aid of an example in FIGS. 1 to 6 and described in more detail below, details which are known to the person skilled in the art being dispensed with. Show it:

Fig. 1

a cross section through the upper support body

Fig. 2

a rolling ring

Fig. 3

a longitudinal section through a support body with rolling rings, rotating and clamping device

Fig. 4

a clamping cylinder with a plate spring

Fig. 5

the arrangement of the drive shaft

Fig. 6

a drive unit

In Fig. 1 the upper part of a planetary mill is shown in cross section. The chock 1, in which the support body 2 is held in the stand 4, is guided in the stand 4 by means of strips 3. These strips 3 are unscrewed when the chocks 1 are rotated (in the example by 90 °) and screwed back into the new mounting position on the vertical side faces of the chocks 1. The four rolling segments 5 are screwed into the support body 2 offset by 90 °. Due to the geometry of the rolling segments 5 which differs from an exact cylindrical shape, the work rolls 6, which are supported on the intermediate rolls 7, are guided in the roll gap in such a way that the rolling material 8 receives a perfect surface. The work rolls 6 are drawn in the direction of the support body axis 9 as they rotate around the support body 2 by disc spring assemblies (not shown). The four clamping devices 10 arranged in the support body 2 lie between the rolling segments 5.

In order to prevent the intermediate rollers 7 from being lifted and abruptly replaced when the rolling segments 5 that are not in the working position, ie, directly opposite one another, each support body 2 is provided with a rolling ring 11 at both ends, as shown in FIG. 2. These rolling rings 11, on which the intermediate rolls 7 roll, can be rotated on the supporting body 2, but are arranged in a locked manner during the rolling, and apart from a recess 12 in the area of the roll gap circular profile.

In Fig. 3 the two devices are shown, by means of which the two rolling rings 11 can be locked or rotated on the support body 2. Only one of the eight clamping devices 10, which are arranged in each support body 2, is shown here. To rotate the rolling rings 11 mounted on the support body 2, the clamping devices 10 (details are explained with reference to FIG. 4) are released. The drive takes place via the drive unit 35 (details are explained with reference to FIG. 6) and a shaft 14 mounted in a recess 13 of the support body 2. The pinion 15 fastened on the shaft 14 is in engagement with one of the two drive pinions 16, which are on a shaft 18 extending in a bore 17 of the support body 2 are fastened. These drive pinions 16 are in engagement with the internal toothing 19 of the rolling rings 11.

4, the clamping device is shown. The rolling ring 11 has an annular groove 20 into which the head or the sliding block 21 of the tie rod 22 engages. The tie rod 22 also represents the piston rod of the clamping cylinder 23, which is arranged in a bore 24 of the support body 2. By means of the plate spring 25, which is supported on the one hand on the inner wall 26 of the clamping cylinder 23 and on the other hand on the piston 27 provided with a seal 28, the rolling ring 11 with the inner surface 29 is pulled firmly against the support body 2. To rotate the rolling rings 11, the cylinder spaces 30 are subjected to such a high pressure that the tensioning force of the plate springs 25 is overcome.

Fig. 5 shows the arrangement of the shaft 14 in the Recess 13 of the support body 2. The pillow block bearing is designated 31. The pinion 15, a drive pinion 16 and a rolling segment 5 can also be seen.

The drive unit 12 (FIG. 6) consists of a stepper motor 32 which is flanged to a hydraulic amplifier 33 (for example an electrohydraulic rotary amplifier, type SVIR from Hartmann & Lämmle). The output side of the hydraulic reinforcement 33 is connected to a self-locking gear 34 (for example a worm gear).

Claims (7)

1. A roll stand for a planetary rolling mill with stanchion (4), stationary supporting members (2), mounted in chocks (1), with rolling segments (5) and intermediate and working rolls (6, 7) which revolve about the supporting members and are mounted in cages, characterised in that the chocks (1) have a square basic form, and each supporting member (2) is equipped with four rolling segments (5) distributed evenly over the periphery and on each end with a rotatable rolling ring (11) which has a recess (12).
2. A roll stand in accordance with the preamble of Claim 1, characterised in that the chocks (1) have an octagonal basic form, and each supporting member (2) is equipped with eight rolling segments (5) distributed evenly over the periphery and on each end with a rotatable rolling ring (11) which has a recess (12).
3. A roll stand according to Claim 1 or 2, characterised in that the two rolling rings (11) of each supporting member (2) can be rotated relative to the supporting member (2) by a rotation means and can be braced against the supporting member (2) by clamping devices (10).
4. A roll stand according to Claim 3, characterised in that the rolling rings (11) have internal teeth (19) and the rotation means consists of a stepping motor (32) of a hydraulic reinforcement (33), which motor is installed outside the chocks (1), a self-locking gear (34) and a shaft (18) with drive pinions (16) attached thereto which runs in bores (17) in the supporting member (2).
5. A roll stand according to Claim 3 or 4, characterised in that the clamping devices (10) consist of clamping cylinders (23) with plate springs (25), which are located in the supporting members (2), and tie rods (22), and that the rolling rings (11) have annular grooves (20) on the side (29) facing the supporting member (2) for receiving the tie rods (22).
6. A roll stand according to one of Claims 1 to 5, characterised in that the chocks (1) are each equipped with two bars (3) which are screwed on corresponding to the fitting position of the supporting members (2).
7. A roll stand according to one of Claims 1 to 6, characterised in that the supporting members (2) have on each end trunnions which project outwards beyond the chocks (1).

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