AU5353100A

AU5353100A - Apparatus for tensioning conveyor belts and bucket elevators

Info

Publication number: AU5353100A
Application number: AU53531/00A
Authority: AU
Inventors: Eric Douglas Charles Mann
Original assignee: Individual
Current assignee: Individual
Priority date: 1999-07-21
Filing date: 2000-08-21
Publication date: 2001-03-22

Description

P/00/011 28/5/91 Regulation 3.2

AUSTRALIA

Patents Act 1990

ORIGINAL

COMPLETE SPECIFICATION STANDARD PATENT Name of Applicant: Actual Inventor: Address for service is: Eric Douglas Charles Mann Eric Douglas Charles Mann WRAY ASSOCIATES 239 Adelaide Terrace Perth, WA 6000 Attorney code: WR Invention Title: Apparatus For Tensioning Conveyor Belts And Bucket Elevators Details of Associated Provisional Application No(s): PQ1760 The following statement is a full description of this invention, including the best method of performing it known to me:- -2-

TITLE

"Apparatus for Tensioning Conveyor Belts and Bucket Elevators" FIELD OF THE INVENTION The present invention relates to an apparatus for tensioning conveyor belts and bucket elevators.

BACKGROUND ART Prior apparatus for tensioning conveyor belts have used a nut and bolt arrangement to hold the tail pulley in place. In such arrangements, the tail pulley is mounted to a conveyor belt frame on slide bearings. The slide bearings have S 10 a bolt projecting from it that passes through the end of the conveyor belt frame and is held in place by a nut. The amount of tension placed on the conveyor belt can be adjusted by tightening or loosening the nut holding the bolt in place.

This arrangement requires that the bolt be placed at the end of the conveyor belt.

The force exerted through the bolt effectively 'pulls' the tail pulley towards the end of the conveyor belt frame.

The use of such an arrangement introduces several problems. Adjusting the tension of the conveyor belt requires manual tightening or loosening of the nut.

This presents a safety hazard to the worker on medium and large conveyor belts where the bolt and nut are under extreme forces. Further, the manual application of force necessary to tighten such a nut can result in back problems and other muscle strain.

Also, where the conveyor belt is used in areas exposed to salt, such as in a salt refinery or in an area close to salt water, the bolt and nut tend to corrode and cease up. This can make adjusting the nut impossible therefore requiring the nut and bolt to be replaced.

-3- Further, conveyor belts can be found in areas where heavy machinery is frequently operated. The use of such machinery in proximity to a conveyor belt fitted with the nut and bolt tensioning arrangement frequently results in damage and the possible sheering of the nut and the part of the bolt that protrudes from the end of the conveyor belt frame. When this occurs the tail pulley is released from its 'pulling' force and the contraction forces exerted by the conveyor belt take over drastically reducing the tension previously applied.

Finally, when a conveyor is started, increased tension is placed upon the conveyor belt and the tail pulley. As the conveyor belt slowly picks up speed, this tension gradually decreases until the final operating tension of the belt is reached. The increased tension can reduce the life of the conveyor belt. At present, compensating for the increased tension can only be obtained through manual adjustment of the nut, which is a slow and potentially dangerous procedure.

DISCLOSURE OF THE INVENTION Throughout the specification, unless the context requires otherwise, the word "comprise" or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers.

20 In accordance with a first aspect of this invention, there is provided a conveyor belt tensioning apparatus comprising: a tail pulley slidably mounted to a frame; and force exerting means extending between the frame and the tail pulley to tension the conveyor belt.

Preferably, said frame includes guide means slidably mounted thereto, and said tail pulley is provided on said guide means.

-4- Preferably, said frame comprises a pair of support members provided one adjacent each side of the frame and an end section extending beyond the support members, said tail pulley being slidably mounted in said end section.

Preferably, said end section comprises a pair of 'C'-shaped members provided one at each side of the frame, said guide means comprising a pair of plates that are received in a corresponding 'C'-shaped member of the end section.

Preferably, said force exerting means is provided between the support member and the tail pulley.

Preferably, said force exerting means is connected at one end to the support member and at the other end to the guide means.

i*na Preferably, the force exerting means is arranged to maintain a substantially constant force on the tail pulley.

Preferably, said force exerting means comprises a pair of hydraulic rams.

Preferably, said apparatus further comprises control means connecting said hydraulic rams to a source of hydraulic fluid, and an accumulator provided between said control means and said hydraulic rams, said control means being user-operable to provided a hydraulic fluid at a predefined pressure to said hydraulic rams, said accumulator arranged to add or remove hydraulic fluid to oo :said hydraulic rams to maintain the force exerted by the hydraulic rams within a S" 20 predefined range.

In accordance with a second aspect of this invention, there is provided a method for tensioning a conveyor belt provided on a tail pulley, the tail pulley being slidably mounted to a frame in an end section thereof, the frame having support members provided spaced from the end section, comprising the steps of: providing a force exerting means between the support members and the tail pulley to apply a force to the tail pulley such that the tail pulley moves away from the support members and the conveyor belt is thereby tensioned.

Preferably, the method further comprises the step of maintaining the force applied by the force exerting means at a substantially constant amount.

BRIEF DESCRIPTION OF THE DRAWINGS One embodiment of the invention will now be described by way of example, with reference to the accompanying drawings, in which: Figure 1 is a side view of the conveyor belt tensioning apparatus of the embodiment; and Figure 2 is a perspective view of the conveyor belt tensioning apparatus of figure 1.

*4444* BEST MODE(S) FOR CARRYING OUT THE INVENTION .The embodiment is directed towards a conveyor belt tensioning apparatus shown :in the drawings generally at 10. In the embodiment, the apparatus is tensioning a conveyor belt 12.

The conveyor belt 12 is housed in a frame 14 comprising upright support members 16, one provided at each side of the conveyor belt 12. Each support 4member 16 has a pair of inwardly facing "C"-shaped channels 18 extending transversely therefrom. One of the "C"-shaped channels 18 is provided at an "i end of the support column 16 and the other is provided spaced from that end. A plate 20 extends across the end of the frame 14.

The tensioning apparatus 10 comprises a tail pulley 22, a pair of hydraulic rams 24 and a controller (not shown).

The tail pulley 22 comprises a roller 26, at each end of which is provided a mounting plate 28 to which the roller 26 is mounted by a bearing (not shown).

Each mounting plate 28 is attached to a pair of guide plates 30 that are received -6within the "C"-shaped channels 18 so as to be slidably mounted to the frame 14.

The tail pulley 22 is able to slide along the "C"-shaped channels 18.

Each hydraulic ram 24 extends between one of the support members 16 and one of the mounting plates 28. The hydraulic rams 24 are provided to each side of the roller 26. The hydraulic rams 24 are operated by the controller (not shown).

The hydraulic rams 24 are also connected to an accumulator (not shown) which is provided in the conduit passing hydraulic medium to the hydraulic rams 24.

The accumulator either stores hydraulic medium or releases hydraulic medium according to the pressure of the hydraulic medium and the activation pressure of the accumulator. A pressure gauge is also provided in the fluid conduit, providing a convenient mechanism for measuring the tension on the conveyor belt.

lo The hydraulic rams 24 exert a force on the tail pulley 22 pushing the tail pulley 22 toward the end plate 20 so as to tension the conveyor belt 12. Advantageously, the hydraulic rams are provided internal to the frame 14, and no parts protrude beyond the end plate 20. Further, the use of hydraulic rams 24 simplifies the process for adjusting the tension of the conveyor belt 12. The user can simply adjust the amount of hydraulic medium supplied to the hydraulic rams 24 to increase or decrease tension on the conveyor belt 12.

20 In use, the activation pressure of the accumulator (not shown) is chosen to be commensurate with the pressure required to maintain the normal operating tension on the conveyor belt 12 when in operation. The controller is used to adjust the amount of hydraulic medium supplied to the hydraulic rams to provide the desired tension on the conveyor belt 12. During this normal operation, the hydraulic rams 24 exert force on the tail pulley 22, thereby tensioning the conveyor belt 12.

When the conveyor belt 12 is initially started, the conveyor belt 12 is placed under increased tension. This increased tension results in the tail pulley 22 exerting a greater reactionary force on the hydraulic rams 24. In turn, this -7increases the pressure of the hydraulic medium. When the activation pressure of the accumulator is reached, hydraulic medium is drawn from the hydraulic rams 24 into the accumulator. This acts to reduce the force exerted by the hydraulic rams 24 which in turn reduces the tension on the conveyor belt 12. As the conveyor belt picks up speed, the tension on the conveyor belt decreases to its normal operating level, and the tail pulley will exert a decreasing reactionary force on the hydraulic rams 24. In turn, this reduces the pressure of the hydraulic medium and the hydraulic medium is returned from the accumulator to the hydraulic rams 24 to maintain the desired operating tension on the conveyor belts 12.

It should be appreciated that this invention is not limited to the particular embodiment described above.

0o

Claims

1. A conveyor belt tensioning apparatus comprising: a tail pulley slidably mounted to a frame; and force exerting means extending between the frame and the tail pulley to tension the conveyor belt.

2. A conveyor belt tensioning apparatus as claimed in claim 1, said frame includes guide means slidably mounted thereto, and said tail pulley is provided on said guide means.

3. A conveyor belt tensioning apparatus as claimed in any one of claims 2, 10 wherein said frame comprises a pair of support members provided one adjacent each side of the frame and an end section extending beyond the support members, said tail pulley being slidably mounted in said end section.

4. A conveyor belt tensioning apparatus as claimed in claim 3, wherein said end section comprises a pair of 'C'-shaped members provided one at each side of the frame, said guide means comprising a pair of plates that are received in a corresponding 'C'-shaped member of the end section.

A conveyor belt tensioning apparatus as claimed in any one of claims 1 to 4, wherein said force exerting means is provided between the support member and the tail pulley.

6. A conveyor belt tensioning apparatus as claimed in claim 5, wherein said force exerting means is connected at one end to the support member and at the other end to the guide means.

7. A conveyor belt tensioning apparatus as claimed in claim 6, wherein the force exerting means is arranged to maintain a substantially constant force on the tail pulley. -9-

8. A conveyor belt tensioning apparatus as claimed in claim 6 or 7, wherein said force exerting means comprises a pair of hydraulic rams.

9. A conveyor belt tensioning apparatus as claimed in claim 8, further comprising control means connecting said hydraulic rams to a source of hydraulic fluid, and an accumulator provided between said control means and said hydraulic rams, said control means being user-operable to provided a hydraulic fluid at a predefined pressure to said hydraulic rams, said accumulator arranged to add or remove hydraulic fluid to said hydraulic rams to maintain the force exerted by the hydraulic rams within a predefined range.

10.A method for tensioning a conveyor belt provided on a tail pulley, the tail pulley being slidably mounted to a frame in an end section thereof, the frame S-having support members provided spaced from the end section, comprising the steps of: providing a force exerting means between the support members and the tail pulley to apply a force to the tail pulley such that the tail pulley moves away from the support members and the conveyor belt is thereby tensioned. S.

11.The method of claim 10, further comprising the step of maintaining the force applied by the force exerting means at a substantially constant amount. Dated this Twenty-first day of August 2000. Eric Douglas Charles Mann Applicant Wray Associates Perth, Western Australia Patent Attorneys for the Applicant(s)