WO2013066239A1

WO2013066239A1 - Method and arrangement for adjustable play in a rotating machine

Info

Publication number: WO2013066239A1
Application number: PCT/SE2012/050978
Authority: WO
Inventors: Jan Laredius; Kjell SJÖDIN
Original assignee: Metso Paper Sweden Ab
Priority date: 2011-11-03
Filing date: 2012-09-17
Publication date: 2013-05-10
Also published as: SE1151033A1; SE536081C2

Abstract

A rotating machine (1) has a rotor (10), an outer bearing housing (20), a bearing (30) arranged for supporting radial forces between the rotor (10) and the outer housing (20) by mechanical contacts, and an inner bearing housing (40) of the rotor ( 10) being in direct mechanical contact with the bearing (30), and the outer bearing housing (20) and inner bearing housing (40) are arranged to be in axial sliding engagement with each other. The rotating machine (1) further comprises at least one sliding unit (41) arranged on an outer surface of the inner bearing housing (40), and at least one adjustable spacer unit (50) arranged between said sliding unit (41) and said outer bearing housing (20). Further, the rotating machine (1) includes at least one engaging unit (60) configured to engage and cooperate with the adjustable spacer unit (50), and the adjustable spacer unit (50) are configured to provide a predetermined play (δ) between the inner bearing housing (40) and the outer bearing housing (20).

Description

METHOD AND ARRANGEMENT FOR ADJUSTABLE PLAY IN A

ROTATING MACHINE

TECHNICAL FIELD The present disclosure relates to a rotating machine, in particular to an arrangement for enabling an adjustable play in such a machine.

BACKGROUND In all rotating machines, there is some sort of bearings e.g. radial bearings for supporting radial forces between a rotor part and a stator part by mechanical contact. Typical examples of bearing types used as such bearings are ball bearings, roller bearings, and sliding bearings. Furthermore, some types of rotating equipment necessitate axial movement between the rotating shaft and a stator e.g. stationary housing because of impeller clearance, replacement, and adjustment. Refiners, used in the pulp and paper industry can have longitudinal adjustment requirements in excess of 50 mm.

In order to provide both a reliable radial support, whilst maintaining the possibility of a smooth axial movement, it is often desired to maintain a play between the rotating shaft and the stator. In prior art this has typically resulted in a complete disassembly of the equipment, and potentially replacement of the entire rotor assembly in order to be able to control the play, which is both time consuming and costly.

Therefore, there is a need for an improved manner of providing the play between the inner and outer housing, which is less labor intense and less costly for the end consumer. SUMMARY

An object of the present invention is to provide an arrangement, which enables a predetermined play between a rotor and a stator in a rotating machine. A further object is to provide an arrangement, which provides an adjustable play between the rotor and stator.

The devices and methods according to the enclosed claims achieve the above objects. In general words, according to a first aspect, a rotating machine has a rotor, an outer bearing housing, a bearing arranged for supporting radial forces between the rotor and the outer housing by mechanical contacts, and an inner bearing housing of the rotor being in direct mechanical contact with the bearing, and the outer and inner bearing housings are arranged to be in axial sliding engagement with each other. The rotating machine further comprises at least one sliding unit arranged on an outer surface of the inner bearing housing, and at least one adjustable spacer unit arranged between the sliding means and the outer bearing housing. In addition, the rotating machine includes at least one engaging unit configured to engage and cooperate with the adjustable spacer unit, and the adjustable spacer unit is configured to provide a predetermined play between the inner and outer bearing housing.

In a second aspect, a method of providing a play in a rotating machine, where the rotating machine comprises a rotor, an outer bearing housing, a bearing arranged for supporting radial forces between the rotor and the outer bearing housing by mechanical contacts, an inner bearing housing of the rotor being in direct mechanical contact with said bearing, comprises adjusting an axial displacement of at least one adjustable spacer unit arranged between at least one sliding unit arranged on an outer surface of the inner bearing housing and the outer housing, to provide an adjustable predetermined play between the inner and outer bearing housing. One advantage with the present invention is that it enables an easily adjustable play. BRIEF DESCRIPTION OF THE DRAWINGS

The invention, together with further objects and advantages thereof, may best be understood by referring to the following description taken together with the accompanying drawings, in which:

FIG. 1 is a schematic cross-section of a refiner according to prior art in which the present disclosure can be beneficially applied;

FIG. 2 is a schematic cross-section of an embodiment of an arrangement according to the present disclosure;

FIG. 3 is a schematic cross-section of a further embodiment of an arrangement according to the present disclosure;

FIG. 4 is a side view of the embodiment of FIG. 2;

FIG. 5 is a side view of the embodiment of FIG. 3;

FIG. 6 illustrates a further embodiment of the present invention, when mounted in a refiner;

FIG. 7 is a flow diagram of an embodiment of a method according to the present disclosure.

DETAILED DESCRIPTION

Throughout the drawings, the same reference numbers are used for similar or corresponding elements.

By having analyzed behaviours of refiners in pulp plants, it has been found that play in general in rotating machines not only determines friction and wear properties, but is also closely connected with different types of vibration properties. By combining knowledge about preferred operating parameters at different operating conditions, a general understanding has developed that it is of importance to be able to control play in a different manner in different conditions e.g. both depending on a potential need for a varying play or depending on conditions affecting the play and thus necessitating adjustments in order to maintain a desired play. Solutions only aiming at keeping the play constant are thus of less importance. In order to further explain the benefits and implications of the present invention, a known refiner arrangement will be described below.

With reference to FIG. 1 , a refiner e.g. disc refiner, comprises two opposing refiner discs 2, 3 between which pulp and/ or wood chips are converted into at least partly separated fibers. At least one of the two discs 2, 3 is rotary and supported on a rotary shaft 10. In such a disc refiner the shaft 10 is mounted in a stand via a bearing housing comprising at least two bearings, one of which is a bearing for carrying axial forces from the refiner disk as well as prevailing radial forces, and one is a bearing intended primarily to carry radial forces.

In a typical refiner, there is often an axially moveable shaft unit in order to provide for an adjustable refining gap between the two opposing refining disks. Typically, the shaft unit moves in an outer bearing housing or stand. In order to provide the necessary radial rigidity of the axel package and mounting, it is required to have a sliding engagement, which takes account of the radial forces but still allows for a smooth axial movement. Often a sliding surface or a sliding band is used, which when mounted typically provides a residual play between the outer and inner bearing housing. In order to control this play, it has been customary to utilize various solutions such as e.g. shims. Shims comprise thin stacks of metal plates that are inserted between the sliding surface or band and the inner surface of the outer housing to provide a predetermined play. However, as the sliding surface is worn down more shims need to be inserted, which also requires disassembly of the bearing housing. In addition, if no shims are used the outer housing will be worn and need to be replaced eventually. Consequently, it is labor intense and costly to accomplish the predetermined play. Failure to adjust the play can cause severe problems with vibrations, and thereby cause accelerated wear of components. In a disk refiner, the two opposing refining disks are moved in relation to each other. The disks have a significant extension perpendicular to the shaft, and heavy radial as well as longitudinal forces have to be carried by the bearing arrangements. The forces can amount to several tens of tons, and the bearing design is therefore of crucial importance for refiners. The arrangements in the present disclosure are therefore advantageously applied to refiners.

With reference to FIG. 2, an embodiment of a rotating machine according to the present invention will be described below. The rotating machine 1 comprises a rotor 10, an outer bearing housing 20, a bearing 30 arranged for supporting radial forces between the rotor 10 and the outer housing 20 by mechanical contacts, and an inner bearing housing 40 of the rotor 10 is in direct mechanical contact with the bearing 30, the outer bearing housing 20 and the inner bearing housing 40 are arranged to be in axial sliding engagement with each other. In order to provide an adjustable play δ between the outer and inner housing 20, 40 the rotating machine 1 further includes at least one sliding unit 41 e.g. a sliding band or surface arranged on an outer surface of the inner bearing housing 40, facing an inner surface of the outer housing 20, and at least one adjustable spacer unit 50 arranged between the sliding unit 41 and the outer bearing housing 20. Further, the rotating machine 1 comprises at least one engaging unit 60 e.g. a cavity with a corresponding size and shape to the spacer unit, configured to engage and cooperate with the adjustable spacer unit 50, and the adjustable spacer unit 50 are configured to provide a predetermined play δ between the inner bearing housing 40 and the outer bearing housing 20. According to a specific embodiment, the adjustable spacer unit 50 comprises a detachable element that can be inserted and brought into cooperation with the engaging unit 60 of the outer housing. In particular, the engaging unit 60 comprise a cavity in the outer housing with a corresponding shape to the adjustable spacer unit. However, it is equally possible to arrange the spacer unit and engaging unit in some other fashion to provide the adjustable play.

With reference to FIG. 3, a further embodiment of the present disclosure will be described. In this case, the adjustable spacer unit 50 comprise at least one tapered or wedge shaped unit, which cooperates with a correspondingly at least one tapered cavity 60 in the outer housing 20. It is possible to utilize only one such spacer unit, however, it is also beneficial to utilized a plurality of such spacer unit arranged at predetermined intervals around the circumference of the inner housing and with corresponding engagement units arranged in a corresponding manner in around the inner circumference of the outer housing. In FIG. 5, an end view of an embodiment with both one and four spacer units 50 are illustrated. The optional four- spacer unit configuration is indicated by dotted contours.

In the present disclosure, the term "bearing housing" is used for any structure being in direct mechanical contact with the bearing. The bearing housing can be a separate item. However, the bearing housing can also be a portion of the stator or rotor itself, having the same main purpose as a bearing housing and being provided in the absolute vicinity of the bearing. In other words, the bearing housing can be a separate unit or an integrated part of the stator or rotor.

With reference to FIG. 5, a further embodiment of the present invention will be described. In this case, the adjustable spacer unit 50 comprise a conical annular unit, which is brought into engagement with a correspondingly conical annular cavity in the outer housing. According to a further embodiment, not shown, the conical annular unit could comprise a plurality of sections together forming a discontinuous conical annular unit. The annular unit could comprise anything from one to two to a plurality of sections depending on the specific circumstances. With reference to FIG. 6 a further embodiment of the present invention will be described. The embodiment is illustrated, as it would appear if implemented in an enlarged upper left portion of the prior art refiner of FIG. 1. In this case, the spacer unit 50 comprises a mainly conical annular unit with an outer non-conical or cylindrical shape. This prevents the spacer unit from being mounted too far into the corresponding cavity in the outer housing. In other words, this provides an upper limit or certain maximum play to the arrangement. Although the previous embodiments have been described as wedge shaped, this entails also other generally wedge or conical shapes that include sections with some other general shape, such as is the case in FIG. 6.

The conical play adjuster can be configured to be adjustable by means of an axially inserted screw or bolt, which when loosened or tightened enables the play adjuster to move into or out of the corresponding cavity in the outer housing and thereby adjust the play. In other word, when the play adjuster moves into the cavity, it will cause the play to decrease, whereas when it moves out of the cavity it will increase the play. In addition, other mechanical or electrical solutions to adjusting the spacer unit can be envisioned without differing from the general concept of the present invention.

FIG. 6 illustrates the main steps of an embodiment of a method of providing a play in a rotating machine, which rotating machine comprises a rotor; an outer bearing housing, a bearing arranged for supporting radial forces between the rotor and the outer bearing housing by mechanical contacts, an inner bearing housing of the rotor being in direct mechanical contact with the bearing. The method includes the step of adjusting S 10 an axial displacement of at least one adjustable spacer unit arranged between at least one sliding unit arranged on an outer surface of the inner bearing housing and the outer housing, to provide a predetermined play between the inner and outer bearing housing. Optionally, the method comprises the further steps of selecting or determining S I a predetermined play, measuring S2 an actual play in the rotating machine and finally adjusting the play based on the predetermined play and actual play to provide the predetermined play.

By utilizing the conical solution according to the present invention, it is possible to adjust the play at will and on location instead of disassembling the entire shaft unit. In addition, by providing a replaceable insert it reduces the risk of sliding wear on the outer housing, which is further cost saving.

The embodiments described above are to be understood as a few illustrative examples of the present invention. It will be understood by those skilled in the art that various modifications, combinations, and changes may be made to the embodiments without departing from the scope of the present invention. In particular, different part solutions in the different embodiments can be combined in other configurations, where technically possible. The scope of the present invention is, defined by the appended claims.

Claims

1. A rotating machine (1) comprising a rotor (10), an outer bearing housing (20), a bearing (30) arranged for supporting radial forces between said rotor (10) and said outer housing (20) by mechanical contacts, and an inner bearing housing (40) of said rotor ( 10) being in direct mechanical contact with said bearing (30), said outer bearing housing (20) and said inner bearing housing (40) being arranged to be in axial sliding engagement with each other;

characterized by

at least one sliding unit (41) arranged on an outer surface of the inner bearing housing (40),

at least one adjustable spacer unit (50) arranged between said sliding unit (41) and said outer bearing housing (20),

at least one engaging unit (60) configured to engage and cooperate with said adjustable spacer unit (50), and

said adjustable spacer unit (50) is configured to provide a predetermined play (δ) between said inner bearing housing (40) and said outer bearing housing (20).

2. The machine according to claim 1 , characterized by said adjustable spacer unit (50) comprising a wedge shaped unit, and said engaging unit (60) comprising a correspondingly shaped cavity in said outer housing.

3. The machine according to claim 2, characterized by said adjustable spacer unit (50) being configured to be adjustable by being moveable along an axial direction relative said outer bearing housing and said rotor (10).

4. The machine according to claim 2, characterized by said at least one adjustable spacer unit (50) comprising a plurality of wedge shaped units arranged around the circumference of said inner bearing housing (40),

5. The machine according to claim 2, characterized by said wedge shaped unit comprising an annular conical unit arranged on said inner bearing housing (40).

6. A refiner arrangement (2), characterized by said refiner arrangement comprising a rotating machine (1) according to any of claims 1-5.

7. A method of provide a bearing play in a rotating machine, said rotating machine comprising a rotor; an outer bearing housing, a bearing arranged for supporting radial forces between said rotor and said outer bearing housing by mechanical contacts, an inner bearing housing of said rotor being in direct mechanical contact with said bearing, said method being characterized by the steps of:

adjusting (S 10) an axial displacement of at least one adjustable spacer unit arranged between at least one sliding unit arranged on an outer surface of the inner bearing housing and said outer housing, to provide a predetermined play between said inner bearing house and said outer bearing housing.

8. The method according to claim 7, characterized by the further steps of determining (S I) a desired play, measuring (S2) an actual play, and adjusting (S 10) said axial displacement based on said desired play and said actual play.