AU689152B2

AU689152B2 - Vertical guiding mechanism

Info

Publication number: AU689152B2
Application number: AU80499/94A
Authority: AU
Inventors: Leonard J.A. Wood
Original assignee: Baker Hughes Inc
Current assignee: FLSmidth AS
Priority date: 1994-12-16
Filing date: 1994-12-16
Publication date: 1998-03-26
Anticipated expiration: 2014-12-16
Also published as: ZA9510629B; CA2164928C; AR001754A1; CA2164928A1; AU8049994A

Description

P/00/011I Regulation 3.2

AUSTRALIA

Patents Act 1990

ORIGINAL

COMPLETE SPECIFICATION STANDARD PATENT *000 0* 00 0 .0.0 00 00 0 0000 0000 0**0 0 0000 0 00 00 0 Invention Title: VERTICAL GUIDING MECHANISM The following statement is a full description of this invention, including the best method of performing it known to us: 00 0 *0 0 00 000000 0 00 00 0 0000 000000 I, 0 FIIPMELCDW43SM13I2 IC1 I CQ972730276

I

VERTICAL GUIDING MECHANISM FIELD OF THE INVENTION This invention relates to a guiding assembly for maintaining a rotary drive assembly, such as is used in mining and/or fluid thickening operations, in a desired orientation whilst raising or lowering the drive assembly. The invention also relates to a rotary drive lifting assembly which contains such a guiding assembly. Typically these are used in liquid/solids sedimentation to raise and lower rotatable rake arms which engage settled solids within the tank and move the solids to a tank bottom outlet.

BACKGROUND OF THE INVENTION Vertical rotary drive shafts are generally fitted with lifting means capable of raising and S: lowering the drive shaft as required. Normally, the drive shaft is located in slideable engagement with a surrounding sleeve which serves to assist in maintaining the drive shaft in substantially vertical orientation. The sleeve is engaged with a motor so that, in operation, the motor rotates the sleeve. The sleeve and the drive shaft are connected so rotation of the sleeve 15 also rotates the drive shaft. This connection is typically a sliding guide key arrangement by which drive torque is transmitted from the sleeve to the vertical drive shaft.

These types of devices have many uses in the mining industry and are also used in liquid/solids

Q

sedimentation assemblies. Thickeners or settling apparatus are used for solid-liquid separation of slimes, slurries and sludges.

Such settling apparatus generally includes a relatively large settling tank and rotary rakes supported within the tank. The rakes are driven to move settled material to a central area outlet or to the tank periphery outlet.

It is well known that the vertical drive shaft connected to the rotary rakes is subjected to very high torques when rotated. The degree of torque experienced by the shaft is dependent upon the resistance to rotation experienced by distant portions of the shaft. This resistance arises primarily as a result of rakes at the end of the shaft encountering resistance as they are rotated in a liquid or through settled solids.

Additional stresses are placed upon the shaft when horizontal forces are also brought to bear on the shaft. For instance when the shaft is deflected from its vertical position or where, in thickening operations, different densities of the sludge being raked by the rake arms place sideway pressures on the vertical shaft.

These torque and horizontal forces on the vertical shaft increase the friction between the shaft and the surrounding vertical sleeve. The amount of friction is proportional to such forces. When

%Q

A41C1CDW43OOO5.9 o t-.

CQo97273027 6 2 the drive shaft is lifted, the lifting means has to overcome these frictional forces in addition to the usual gravitational force. This places additional strain on the lifting means.

In regard to liquid thickener assemblies, most thickeners are fitted with a lifting delvice which is capable of lifting the vertical shaft and rake arms above their normal operating position when it is desired to limit the torque applied to such vertical shaft and rakes. In this arrangement, the lifting device and the sliding guide key arrangement are adapted so that the drive shaft (and rake arm) may be lifted whilst the sleeve is still able to transmit drive torque to the drive shaft.

Under high torque and/or high horizontal pressures, the frictional forces between the shaft and the sliding guide key arrangement may exceed the weight of the shaft and rake arm and require very powerful lifting devices (eg hoists, screw jacks or hydraulic cylinders) to lift the shaft and rake arm.

One type of thickener assembly is column-mounted, that is, it is generally secured on top of a S: rigid column. In such a thickener assembly a rake drive unit is seated on the column, and includes a motor and gear boxes for rotating a cylindrical cage. This cage has one or more vertical legs connected to generally horizontal rake arms. One of the problems with conventional column-mounted thickener assemblies is that large frictional forces are also experienced as a result of the considerable torque forces experienced by the legs and rake arms as the rake arms are rotated through the liquid (or slurry). Accordingly, when using conventional guiding means for maintaining the cage and legs in generally vertical orientation :20 whilst raising (or lowering) them, these large frictional forces increase the amount of lifting force needed by the lifting means and a high powered lifting device is required.

Another lifting device is disclosed in US Patent No 4,624,787 which uses a pulley system to 00 achieve the desired lift. This arrangement is complex and requires constant maintenance of the cable and pulleys.

Australian patent application No 57582/94 describes improved lifting devices for raising and lowering vertical drive shafts with less friction than is experienced in the abovementioned mechanisms. One of the problems of the aspects of the invention described in AU57582/94 is that the 2 upper link arms should be connected together by a heavy box fabrication member to ensure that both link arms stay correctly aligned with each other. Likewise, the 2 lower link arms should also be connected by a heavy box fabrication member for the same reason. The pairs of link arms should be aligned to ensure that there is torsional rigidity in the whole assembly to keep the shaft essentially vertical when subject to sideways loading. The inclusion of the heavy box fabrication members increases the costs of the guiding assembly.

A further problem with the aspects of the invention dscribed in AU57582/94 is that the drive shaft or drive cage (as the case may be) may still undergo a small degree of arcuate movement, FIPELC 9435(05.9 c I ClliBllg~Y"-arr~lln- COE97273027.6 3 when being raised or lowered, owing to the rotation of the link arms. This arcuate motion causes the vertical shaft and rake arms to move towards the wall of the tank in which the rakes operate and additional clearance must therefore be provided.

With the above problems in mind the present invention is directed towards an improved guiding assembly in which such arcuate motion of the drive shaft is eliminated and the links are simple individual assemblies without the need for connecting heavy fabrication assemblies.

SUMMARY OF THE INVENTION The invention provides a lifting mechanism assembly for the rake assembly of a sedimentation tank for settling a liquid solid slurry into its clarified liquid effluent phase and its solid underflow phase settling at the bottom of the tank, including: a tank; a rake assembly positioned in the tank and rotatable about the vertical centre line of the tank; a stationary support positioned at least in part near the centre line of the tank; 'aoo a rotary drive mechanism for rotating the rake assembly; 15 a linkage extending between the stationary support and the rotary drive mechanism, said linkage including at least one elongate member pivotally mounted at one end thereof to the stationary support and pivotally mounted at its other end to the rotary drive mechanism, said pivotal mounts being oriented to provide pivotal movement about a horizontal axis receive and counteract torque created by the rotary drive mechanism in rotating the rake assembly and for enabling vertical movement of the rotary drive mechanism relative to the stationary support; and an actuation mechanism for vertically lifting the rotary drive mechanism and the rake assembly.

Preferably said stationary support is an outer body and said rotary drive mechanism is connected to an inner body, said outer body and said inner body being in substantially co-axial alignment with each other, and wherein said at least one elongate member of said linkage further includes a first set of at least three link arms extending between the inner body and the outer body, each said link arm being pivotally connected at one end thereof to the inner body and being pivotally connected at the other end thereof to said outer body.

Preferably said actuation mechanism is positioned between said inner body and said outer body to effect raising and lowering of said inner body and said rake assembly, Preferably each of said at least three arms are radially spaced from each adjacent link arm by about 1200.

FTlPM ELCD4J35OXJ5.9 I -~~-p~an-ar ('QL97273(127.6 4 Preferably said at least three link arms are of fixed length.

Preferably said at least one elongate member of said linkage includes a second set of at least three link arms, each said link arm being pivotally connected at one end thereof to the inner body and pivotally connected at the other end thereof to said outer body.

Preferably said stationary support is an inner body and said rotary drive mechanism is connected to an outer body, said inner body and said outer body being in substantially co-axial alignment with each other, and wherein said at least one elongate member of said linkage further includes a first set of at least three link arms extending between the inner body and the outer body, each said link arm being pivotally connected at one end thereof to the inner body and being pivotally connected at the other end thereof to said outer body.

Preferably said actuation mechanism is positioned between said inner body and said outer body to effect raising and lowering of said outer body and said rake assembly.

09 Preferably each said at least three arms are radially spaced from each adjacent link arm by about 1200.

15 Preferably said at least three link arms are of fixed length.

Preferably comprising a vertical guide member positioned relative to said stationary support and oriented to guide vertical movement of the rake assembly relative to the stationary support.

The invention further provides a lifting mechanism assembly for the rake assembly of a sedimentation tank for settling a liquid solid slurry into its clarified liquid effluent phase and its solid underflow phase settling at the bottom of the tank, comprising: a tank; a rake assembly positioned in the tank rotatable about the vertical centre line of the tank; a stationary support positioned at least in part at the vertical centre line of the tank; a rotary drive mechanism for rotating the rake assembly, said rotary drive mechanism being fixedly mounted to the stationary support; a linkage extending between the rake assembly and the rotary drive mechanism, said linkage comprising at least one elongate member pivotally mounted at one end thereof to the rake assembly and pivotally mounted at its other end to the rotary drive mechanism, said pivotal mounts being oriented for movement about a horizontal axis for transferring FIIPMELCD4350( OS,9 s CQi91727lO27.

torque created by the drive mechanism in rotating the rake assembly and for enabling vertical movement of the rake assembly relative to the rotary drive mechanism; and an actuation mechanism for lifting the rake assembly.

Preferably said stationary support is a bridge extending across the diameter of said tank, and wherein said actuation mechanism is positioned between said rotary drive mechanism and said rake assembly.

Preferably said rake assembly includes a drive shaft positioned along said vertical centre line of said tank, and further comprising a vertical guide member positioned about said drive shaft for guiding the vertical movement of said rake assembly.

Preferably said stationary support is a column positioned along the vertical centre line of said tank and extending upwardly from the floor of said tank, and wherein said actuation mechanism S is positioned between said rotary drive mechanism and said rake assembly.

Preferably said rake assembly includes a drive cage oriented about the column and extending from the rotary drive mechanism to rake arms positioned near the bottom of the tank, and 15 further comprising a vertical guide member positioned about said column for guiding the vertical movement of said rake assembly.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will now be further illustrated with reference to the accompanying drawings in which, for simplicity, like components are designated with the same numeral: Figure 1 is a perspective view of a simplified version of a preferred aspect of the invention.

Figure 2 is a side view of the aspect of the invention shown in figure Figure 3 is a planside view of the aspect of the invention shown in figure 1.

Figure 3 is a plan view of the aspect of the invention shown in figure 1.

Figure 4 is a plan view, in greater detail, of a portion of the aspect of the invention shown in figure 3.

Figure 5 is a side view of an alternate aspect of the invention.

Figure 6 is a plain view of a connection between a link arm and an inner body of a preferred aspect of this invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS As shown in Figures 1 and 2, a preferred aspect of this invention includes an outer drum 1 and an inner drum 3, said outer and inner drums being joined by link arms 5A, 5B. The inner drum 3 is substantially hollow and has an annular base surface 7. A rotary drive unit 9 is located within the inner drum 3 and is fixedly mounted on the annular base surface 7. The rotary drive F IPMLCDW9435cXX5.q COL97271027 6 unit 9 includes a rake drive motor 11 and a rake drive gearbox 13. A rake drive shaft 15 extends downwardly from the rake drive motor 11 through the annular base surface 7. The outer drum 1 has an annular flange 17 which may be secured to a support, such as a bridge.

As more clearly shown in Figure 3, the link arms 5A, (link arms 5B are not shown in Fig 3) are radially separated from each adjoining link arm 5A by 1200. Link arms 5B are oriented in the same way as link arms 5A. Link arms 5B are displaced in an axial direction, from link arms and are preferably parallel thereto.

As more clearly shown in figures 4 and 6, each link arm 5A, 5B is connected, at its ends, to the respective outer drum 1 and inner drum 3 by means of supporting brackets 19. Each supporting bracket 19 has a recess 21 for receiving a respective end of the relevant link arm 5A, 5B. Each recess 21 is dimensioned in order to allow rotational movement of the end of the link arm 5B within the recess 21. The link arms 5A, 5B are secured to the brackets 19 by means of pins 23 about which the link arms 5A, 5B may rotate. The connection between the ends .f dAe link arms 5A, 5B and the pins 23 is by way of a spherical plane bearing assembly which allows the 15 link arm 5A, 5B to move laterally relative to the pin 23 in order to accommodate the slight twisting (or rotational) motion of the inner drum 3 relative to the outer drum 1 as the inner drum 3 moves in an axial direction relative to outer drum 1. In order to allow for this lateral movement of each link arm 5A, 5B, there is a small space 25 between the end of each link arm 1: 5A, 5B and the sides of each recess 21 of the brackets 19.

20 Lifting means, such as hydraulic cylinders (not shown), can be employed to raise and lower the rotary drive assembly.

In use, the inner drum 3 can be raised or lowered relative to the outer drum 1 by means of the lifting mechanism. As the inner drum 3 moves up or down relative to the outer drum 1, the link arms 5A, 5B rotate about the pins 23. As the link arms 5A, 5B rotate, the inner drums rotates (or twists) slightly about its axis. This also causes the end of each link arm 5A, 5B which is connected to the inner drum 3 to undergo some degree of lateral movement (towards or away from) the outer drum 1.

An alternative aspect of the invention is shown in Figure 5 which shows a fixed hollow central column 1 and a movable inner drum 3. The column 1 may be fixed to a floor of a tank or reservoir. The positions of the link arms 5A, 5B are shown in outlie. The rotary drive unit (not fully shown), including the rake drive gearbox 13, is located on top of the inner drum 3. In this aspect of the invention, rake arms (or an external cage with rake arms extending therefrom) (not shown) are joined to the rotary drive nnit. The hollow central column 1 has a horizontal support plate 27 on which is mounted hydraulic cylinders 29 (only one is shown) for raising and lowering the inner drum 3 relative to the central columns.

F1IPM LD\M1 I35Y S.9 IL L ~L Is f'QW|727m027 h 7 In the above alternative aspect of the invention, the operation of the link arms 5A, 5B is substantially identical to their operation described in relation to the other aspects of the invention described above.

The guiding assembly of this invention enables a rotating drive shaft or a rotating drive cage to be raised out of or lowered into a fluid separation tank or other similar system relatively easily owing to the lower frictional forces within the guiding assembly. Accordingly, less force is required to raise or lower the drive shaft or drive cage. This results in lower power requirements and enables relatively cheap lifting mechanisms to be employed. The guiding assembly of this invention also enables the rotating drive shaft or rotating drive cage to be raised and/or lowered in a substantially vertical orientation.

The above may be compared to vertical guiding sleeves or guide key arrangements of the prior art in which horizontal displacement of the drive shaft causes a great amount of friction between "d the shaft and the sleeve or guide key arrangement. In these aspects of the prior art, large forces *0 are required to be applied to overcome the frictional forces and to lift the shaft and/or cage.

As will be appreciated, the invention is not limited to the specific embodiments described above and may have applications in other fields, such as the mining exploration industry.

p pp* p p p

G-

fM-Iu| FIPMELCD\9435000.9 -L -~p

Claims

1. A lifting mechanism assembly for the rake assembly of a sedimentation tank tor settling a liquid solid slurry into its clarified liquid effluent phase and its solid underflo,: phase settling at the bottom of the tank, including: a tank; a rake assembly positioned in the tank and rotatable about the vertit. i ,t -re I of the tank; a stationary support positioned at least in part near the centre line of the tank; a rotary drive mechanism for rotating the rake assembly; a linkage extending between the stationary support and the rotary drive mechanism, said linkage including at least one elongate member pivotally mounted at one end thereof to the S• •stationary support and pivotally mounted at its other end to the rotary drive mechanism, S• said pivotal mounts being oriented to provide pivotal movement about a horizontal axis to receive and counteract torque created by the rotary drive mechanism in rotating the rake assembly and for enabling vertical movement of the rotary drive mechanism ago° relative to the stationary support; and an actuation mechanism for vertically lifting the rotary drive mechanism and the rake assembly.

2. A lifting mechanism assembly as claimed in claim 1, wherein said stationary support is an outer body and said rotary drive mechanism is connected to an inner body, said outer body and said inner body being in substantially co-axial alignment with each other, and wherein said at least one elongate member of said linkage further includes a first set of at least three link arms extending between the inner body and the outer body, each said link arm being pivotally connected at one end thereof to the inner body and being pivotally connected at the other end thereof to said outer body.

3. A lifting mechanism assembly as claimed in claims 1 or claim 2, wherein said actuation mechanism is positioned between said inner body and said outer body to effect raising and lowering of said inner body and said rake assembly.

4. A lifting mechanism assembly as claimed in claim 2 or 3 wherein each of said at least three arms are radially spaced from each adjacent link arm by about 1200. A lifting mechanism assembly as claimed in any one of claims 2 to 4 wherein said at least three link arms are of fixed length.

6. A lifting mechanism assembly as claimed in any one of claims 2 to 5 wherein said at least one elongate member of said linkage includes a second set of at least three link arms, each ;U .tL FHPMELCD\9435O05.9 I dl I ('OIWP7273027 t 9 said link arm being pivotally connected at one end thereof to the inner body and pivotally connected at the other end thereof to said outer body.

7. A lifting mechanism assembly as claimed in claim 1 wherein said stationary support is an inner body and said rotary drive mechanism is connected to an outer body, said inner body and said outer body being in substantially co-axial alignment with each other, and wherein said at least one elongate member of said linkage further includes a first set of at least three link arms extending between the inner body and the outer body, each said link arm being pivotally connected at one end thereof to the inner body and being pivotally connected at the other end thereof to said outer body.

8. A lifting mechanism assembly as claimed in claims 1 or 7 wherein said actuation mechanism is positioned between said inner body and said outer body to effect raising and lowering of said outer body and said rake assembly. •I 9. A lifting mechanism assembly as claimed in claims 7 or 8 wherein each said at least three arms are radially spaced from each adjacent link arm by about 120°. :15 10. A lifting mechanism assembly as claimed in any one of claims 7 to 9 wherein said at least three link arms are of fixed length.

11. A lifting mechanism assembly as claimed in any one of claims 7 to 10 wherein said at least one elongate member of said linkage includes a second set of at least three link arms, each .as said link arm being pivotally connected at one end thereof to the inner body and pivotally connected at the other end thereof to said outer body.

12. A lifting mechanism assembly as claimed in any one of the preceding claims further comprising a vertical guide member positioned relative to said stationary support and oriented to guide vertical movement of the rake assembly relative to the stationary support.

13. A lifting mechanism assembly for the rake assembly of a sedimentation tank for settling a liquid solid slurry into its clarified liquid effluent phase and its solid underflow phase settling at the bottom of the tank, comprising: a tank; a rake assembly positioned in the tank rotatable about the vertical centre line of the tank; a stationary support positioned at least in part at the vertical centre line of the tank; a rotary drive mechanism for rotating the rake assembly, said rotary drive mechanism being fixedly mounted to the stationary support; a linkage extending between the rake assembly and the rotary drive mechanism, said linkage comprising at least one elongate member pivotally mounted at one end thereof to the p| FIIPMELCDW435000)5. II 01'72 7 1iff27 rake assembly and pivotally mounted at its other end to the rotary drive mechanism, said pivotal mounts being oriented for movement about a horizontal axis for transferring torque created by the drive mechanism in rotating the rake assembly and for enabling vertical movement of the rake assembly relative to the rotary drive mechanism; and an actuation mechanism for lifting the rake assembly.

14. A lifting mechanism assembly as claimed in claim 13 wherein said stationary support is a bridge extending across the diameter of said tank, and wherein said actuation mechanism is positioned between said rotary drive mechanism and said rake assembly. A lifting mechanism assembly as claimed in claims 13 or 14 wherein said rake assembly includes a drive shaft positioned along said vertical centre line of said tank, and further comprising a vertical guide member positioned about said drive shaft for guiding the vertical movement of said rake assembly. o, 16. A lifting mechanism assembly as claimed in claim 13 wherein said stationary support is a column positioned along the vertical centre line of said tank and extending upwardly from the 15 floor of said tank, and wherein said actuation mechanism is positioned between said rotary drive mechanism and said rake assembly.

17. A lifting mechanism assembly as claimed in claims 13 or 16 wherein said rake assembly includes a drive cage oriented about the column and extending from the rotary drive mechanism a to rake arms positioned near the bottom of the tank, and further comprising a vertical guide member positioned about said column for guiding the vertical movement of said rake assembly.

18. A lifting mechanism assembly being substantially as herein described with reference to the accompanying drawings. Dated this 6th day of January 1998 Baker Hughes Incorporated by its patent attorneys FREEIILLS PATENT ATTORNEYS FnPMELCD\94I15.1(5.9 s ABSTRACT The invention relates to a guiding assembly, for maintaining a rotary drive assembly in a pre-determined orientation whilst raising or lowering the drive assembly, said guiding assembly including: an inner body; an outer body, located about at least a portion of the inner body and being in substantially co-axial alignment with the inner body, said outer body being movable relative to said inner body in an axial direction; a first set of at least 3 link ar'ms extending between the inner body and the outer body, said link arms being adapted to maintain the inner body and the outer body in substantially co-axial alignment during relative movement of the bodies. 000:0 o• G 0o600 •0*0 °"0 IPM ELCE94M 0) 13,9