Roller with a large rotating speed range

p0001The invention relates to a draw roll unit according to the preamble of claim 1 and known for example from DE-A-3701077 is known, for example those devices for Filamentbearbeitung are also known from DE-A-26 39 458, EP-A-113 407, US-A-3772492, GB-A-1204933 is known.

p0002Such a unit comprises a rotatable shaft and has nowadays a permissible speed range, which is limited by the critical speed in such a way that the permissible range<ul><li>a) is below the second critical speed of the shaft, and</li><li>b) has a "discontinuity" at the first bending critical speed of the shaft.</li></ul>

p0003More critical speeds of the unit (eg frame oscillations or torsional shape of the shaft) can be given by the environment or the clamping operation, but are usually insignificant for restricting the permitted speed in their effect or can be muted by commercial elements.

p0004The critical speeds of the shaft, which are mentioned below in the present specification, referred to only as "the critical speeds".

p0005The meaning of this statement will now be briefly explained with reference to Figure 1 on. This diagram shows merely a horizontal axis with speed between O and a limit L3. Assume a draw roller unit is designed for use at speeds up to L3. This limit value is normally determined by the second critical speed, that is, when the rotational speed of the rotating components of the unit above L3 is increased, damage within an unacceptably short period of time can be expected.

p0006But this unit can not readily be used with any speed below the limit L3. Although within the speed range O to L3 is the first critical speed and lesions are also inevitable when the aggregate over a longer period within a speed range L1 is driven by L2 to this first critical speed, provided that this unit is not very accurate and with great effort was overall balanced. Safe operation is also then only possible if the balance quality is maintained. The operating instructions of such aggregates are therefore demanding that the area is L1 to L2 only Duch drive to get into the safe area L2 to L3.

p0007Nevertheless, if an operation in the range L1 to L2 would need regular vibration of the unit may have to be measured, as eg. by heating, contamination or solving by internal stresses that balance quality could change and thus again a safe operation would be compromised

p0008A continuous operation in the range L1 to L2 is only permissible in any case, if the entire unit is balanced after assembly again. It has to be achieved a very high quality of balancing. If any modifications to the unit (replacement of a rotating part) of the balancing process has to be repeated, which is a significant complication in the operation of such aggregates. It must also be ensured and checked that the balancing quality as not impaired by thermal action (heated draw roll) over time, which may lead to unacceptable vibrations and ev. Damages.

p0009By suitable measures (in particular by vibration damping in the bracket between the unit and the supporting frame) has been tried,<ul><li>the limit to increase L3,</li><li>the resonance region to make L1 to L2 as closely as possible,</li><li>Vibrations of the entire unit to reduce.</li></ul>

p0010Nevertheless, so far as we know each draw roller unit has a more or less wide "forbidden speed zone" below the maximum speed, which limits its use for certain applications. Further, it has heretofore been necessary to balance both the individual rotating parts of the machine as well as the aggregate as a whole. This is cumbersome and expensive, not only in manufacturing but also during maintenance (inserting a spare part) or adaptation of the unit.

p0011From DE-3701077A1 a godet unit with direct godet is known which consists of a godet jacket and a godet this driving electric motor. The rotor of the electric motor and the godet sit rotatably on a respective end of a common shaft for both, which is supported in its central portion in bearings. The Galettenheizung and the housing with the field winding of the electric motor are mounted on the opposite sides of the bearing-receiving machine wall. The critical shaft speed is certainly lie outside the range of the operating speed. In order to increase the critical speed of an auxiliary bearing is provided on the motor-side shaft end of the Galettenwelle which is supported in the motor housing. This support was done preferably resilient and / or damped.

p0012The inventors have now found that it is possible to damp vibrations of a draw roll assembly in such a way that the permissible speed range is continuous up to an upper limit value and may be dispensed with balancing of the assembly as a whole. The benefits will be obvious from the above description.

p0013A draw roller unit according to this invention comprises a heatable galette for Filamentbearbeitung, an electromotive drive for the drive of the galette, a stationary bearing casing for receiving a shaft mounted therein in pivot bearings shaft, on the one end side of the bearing housing of the drive and at the other end side of the godet are connected to the shaft and the pivot bearing are spaced apart in the axial direction, and is characterized in that means for vibration absorption are each provided between the rotary bearings and the bearing housing.

p0014The invention differs from the Galette described in DE-A-2639458 in that the first critical area is not displaced, but is merged with the normal operating range.

p0015Three variants of the assembly are possible, as illustrated by the sketches shown in FIG. 2 In all three diagrams (Figures 2A, 2B and 2C) is the fadenaufnehmende element (the "roller") denoted by R and this element is mounted on a shaft W, so that these two elements together form a rotating part. This part is placed in operation in all three variants by a motor M in rotation about the axis of the shaft W. Here, the rotating part is supported in all three variants via a roller bearing K (or other suitable storage) in a holder or a bearing housing G. The three variants differ only in the position of the motor relative to the storage:<ul><li>is located in Fig. 2A of the motor (comprising a stator on the housing and the rotor on the shaft G W) in the housing G between two bearings,</li><li>is located in Fig. 2B, the motor outside the housing G, and the motor shaft MW is with the roller shaft W via a clutch coupled Ku,</li><li>in Fig. 2C, the wave W is extended outside the housing G and the motor M is directly mounted on the housing so that the rotor again (as in the variant of FIG. 2A) may be applied to the shaft W.</li></ul>

p0016In all three cases, vibration damping D is mounted directly between the bearing and the housing K G. This not only the vibrations but also the imbalance induced bearing loads are kept low and thus extending the life. The invention relates to arrangements for vibration damping. In this context, the following further discharges are mounted.

p0017When storing rotating shafts by bearing the occurring negative phenomena are well known. Fabrication Due arise low runout on the shaft or the rotating parts. This always lead to undesirable vibrations and oscillations of the shaft, which will first be transferred to the housing via the bearing. Such vibrations can reduce the life of the entire arrangement greatly or even lead to breakage of the shaft.

p0018For damping such vibrations, various solutions have become known. In the simplest way, a vibration damping through the involvement induce rubber elastic materials, as was shown in the DE-A-26 39 458 for example. However, it should be remembered that such materials are not suitable for all applications because rubber usually has only a relatively low temperature resistance and is more or less affected by lubricant and especially by aggressive media.

p0019The drawing roller unit according to the invention comprises a heatable godet roll for Filamentbearbeitung, wherein the godet is displaceable by a shaft in rotation, wherein the shaft is guided in a bearing assembly and in which are provided in the bearing arrangement comprises means for damping vibrations.

p0020The bearing is clamped in a spring disposed in a housing bearing bush and surround the sleeve by a narrow gap. The gap may be filled with liquid. In this way, wave oscillations or vibrations of the shaft will still be transferred to the bearing bush, but pass through the sprung bearing of the bush only very subdued for housing.

p0021In a particularly advantageous and simple manner, the bearing bush with O-rings is supported on the housing. The already very temperature-stable O-rings are also exposed to extremely high temperatures, since the bearing bushing dissipates a part of the frictional heat generated in the bearing.

p0022By the O-rings, an annular gap between the housing and the bearing bushing is limited, which is preferably connected to a compressed oil source. In this way, a damping effect is generated at a radial oscillation of the bushing by Oelverdrängung.

p0023After the previously described construction of the inventive draw roller assembly the bearing bush is able to perform at least radial relative movements relative to the housing. In a further advantageous embodiment of the subject invention is now provided to arrange between the housing and the bearing sleeve substantially coaxial with the shaft spring pins, the center the bearing bush and prevent even under radial load an abutment of the bush. To this end, each spring pin is anchored at one end in the housing and at the other end in the bearing bush. For better utilization of the spring properties of the pins in each case a middle portion of the spring pin lies with radial play in a recess of the bearing bush.

p0024In this context, it is particularly simple and advantageous to provide the facing the housing end face of the bearing bush with a circumferential groove for receiving the spring pins. Such a groove is easy to produce. Alternatively, it is conceivable to provide a bore in the bearing bushing for each spring pin, in which the non-gripped area of ​​the spring pin is located so that when relative movement between the bearing bush and the housing an abutment of the pin is prevented from bearing bush.

p0025Advantageously, a plurality of spring pins are anchored at regular angular intervals in the bearing bush.

p0026The bearing bushing can have a substantially L-shaped cross-section, so that the bearing is easy to mount and is exposed in the installed state with a relatively large area to the ambient temperature, whereby considerable advantages with respect to the cooling arise.

p0027It has proved to be expedient if the clamped ends of each spring pin are approximately the same length.

p0028The bearings of the bearing assembly can be supported on a wire mesh on the bearing housing. In this way, a low-cost but effective arrangement for vibration damping of galettes, is simple to manufacture and assemble, requires no maintenance and at any temperature certainly doing its job.

p0029To a particularly advantageous embodiment of the subject invention can be reached, if provided in the bearing arrangement at least two at an axial distance to each other arranged bearing. Such a configuration results in a very effective vibration damping, the constructive overhead is more than offset by a very large bearing life.

p0030It is furthermore particularly advantageous if the wire mesh is formed into a ring body which is disposed between the outer bearing ring and the housing. The removal and installation of the wire mesh is feasible in the simplest form.

p0031Advantageously, can assemble the annular body of several ring segments such that defective become segments are individually replaceable with new ones. In such a configuration, it may be advantageous if between the ring segments spaces are provided, so that mass changes at extremely high temperatures are compensated.

p0032The invention may for example also be embodied such that between the bearing outer ring and the ring segments a bushing disposed.

p0033Examples of arrangements of the invention will now be explained with reference to the further figures of the drawings, wherein show:<ul><li><u>Figure 3</u> A draw roller unit in accordance with Fig. 2C with a bearing assembly according to the second additional element between a galette schematically illustrated and an electric motor drive,</li><li><u>Fig. 4</u> a section through the bearing arrangement of Figure 3, according to the dotted line A -. A, the latter figure,</li><li><u>Fig. 5</u> a sectional view of a bearing assembly according to the first Zusatzanspekt for use in a draw roller unit according to one of the variants shown in Fig. 2,</li></ul>

p0034In Fig. 3 and 4, corresponding parts have the same reference numerals to each other.

p0035In the principal sectional view of FIG. 4 is a bearing housing 1 between a galette schematically shown 2 and an electric motor 3. In the bearing housing 1 are four roller bearings 4, 5, 6, 7 provided for supporting a shaft 8. Two bearings 4, 5 and 6, 7 are arranged parallel to each other and are located in the axial end portions of the bearing housing 1. The roller bearings 4, 5, 6, 7 are wire mesh 9 is supported radially on the bearing housing 1 so that shaft vibration during operation of the Galette 2 are effectively damped.

p0036The Galette 2 essentially consists of a cylindrical outer wall 10 which is open at one end and closed at the right end in the drawing by an end wall 11th On the end wall 11 a hub 12 is integrally formed, in which a cone-shaped end portion 13 of the shaft protrudes 8, wherein the shaft 8 is connected by means of a screw 14 axially to the end wall eleventh Due to the cylindrical jacket wall 10, the disk-shaped end wall 11 and the shaft 8, a circumferential ring space 15 is thus formed, in which a stationary heater 16 is housed. The stationary heater 16 is attached to the housing 2 of the godet roll 17, which is in turn flanged to the bearing housing 1 and secured by screws 18 to the bearing housing first

p0037The section shown in Fig. 4 along the dotted line AA of FIG. 3 shows a comparison with FIG. 3 on an enlarged scale, an embodiment with a ball bearing 19, through which the shaft 8 is passed and which is radially outwardly supported on a wire mesh 9, wherein the wire mesh 9 is provided as a composite of a plurality of ring segments 20 ring body; between the ring segments 20 gaps 21 are provided.

p0038In FIG. 5, 31 designates a shaft which is displaceable, for example, by an unillustrated electric motor drive in rotation, wherein the rotational direction of the shaft 31 is not of importance. On the shaft 31 is seated a ball bearing 32, which consists essentially of an inner bearing ring 33, an outer bearing ring 34 and arranged between the bearing rings 33, 34 rolling elements 35th

p0039The ball bearing 32 sits in turn in a press fit in a bearing bush 36 which has an L-shaped cross section substantially, the bearing bush 36 has a diameter such that between the bearing bush 36 and the shaft 31 a gap 37 and a contact of the above parts 31, 36 is excluded.

p0040The outer radial boundary surface of the bearing bush 36 is supported via two O-rings 38, 39 on a housing 40 so that the housing 36 and 40, a circumferential gap is formed between the outer radial boundary surface of the bearing bush 41st The two O-rings 38, 39 are arranged at a predetermined radial distance from each other, whereby a circumferential annular space 42 is formed, for example, is connected to a source of pressurized oil, not shown. To this end, suitable bores (not shown) are provided in the housing 40th is for the embodiment shown between the left in the representation end face 43 of the bearing bushing 36 and the housing 40 is also a gap exists. From this end face 43 is further from a circumferential groove 44 in which the central portion 45 of a spring pin 46 is situated. The ends 47, 48 of the spring pin 46 are anchored in the housing 40 and in the bearing bush, the spring pin 46, for example, coaxial with the shaft 31 is located. To anchor the ends of the spring pin 46 36 holes 49, 50 are provided in the housing 40 and the bearing bush, in which the spring pin 46 is pressed with its ends 47, 48th Instead of the circumferential groove 44 blind holes may as well be provided in the bearing bush 36th

p0041In operation of the described system, according to FIG. 5, consisting of an uneven running of the shaft 31 following vibrations on the bearing bush 36 are transmitted. The O-rings 38, 39, the spring pins 46 and trapped in peripheral annulus 42 pressurized oil however ensure that the vibrations are transmitted only strongly attenuated in the housing 40th The running of the shaft 31 is a total calm, which immediately reduced bearing stress occurs.