GB1578947A - Sifting machines - Google Patents

Description

(54) IMPROVEMENTS RELATING TO SIFTING MACHINES (71) We, UNITED WIRE GROUP LIM ITED, a British Company of Granton Park Avenue, Edinburgh EH5 1HT, Great Britain, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to a sifting machine of the kind having a sifting screen, means for vibrating the screen, and a tray which is spaced above the screen, extends substantially from end to end of the screen, and is inclined so that it can discharge material to be sifted from one end thereof on to one end of the screen. Such a machine will be referred to hereinafter and in the appended claims as a machine of the kind aforesaid.

In some operations in which a machine of the kind aforesaid is used, it is from time to time required that material fed to the tray should not be discharged to the screen so that the latter has to be bypassed. At present, the only way in which the screen can be by-passed is by covering the screen with an imperforate plate or sheet, and this involves considerable time, labour and expense.

An object of the present invention is to provide in such a machine, an improvement whereby the screening stage may be by-passed in a quick, simple, and inexpensive manner.

According to the present invention there is provided a machine of the kind aforesaid having an improvement consisting in that the tray is pivotally mounted so that it can be pivoted, when required, from the inclined position in which it discharges from said one end thereof on to said one end of the screen, to an oppositely inclined position in which it discharges at its other end clear of the screen, and means is provided for releasably locking the tray in each of said positions.

An embodiment of the invention will now be described, by way of example, with reference to the accompanying drawing, in which: - Fig. 1 is a partly schematic side view of a sifting machine incorporating a tray according to the present invention, Fig. 2 is an end view corresponding to Fig. 1, with parts removed, Fig. 3 is a fragmentary view corresponding to Fig. 1, to a larger scale, and showing a modification, and Fig. 4 is a cross-sectional view corresponding to Fig. 2, showing more detail, and with the chute omitted.

Referring to Figs. 1 and 2 of the drawings, tray (or chute) 1 is pivotally mounted on a transverse shaft 2 located intermediate its ends, the shaft 2 being supported at opposite ends by opposed brackets 3 depending from the superstructure or framework 4 of the machine. The shaft 2 is secured to the bracket 3, by nuts 3A which are screwed on to end portions of the shaft which project through holes in the respective brackets 3. A washer 3B is provided between each of the nuts and the brackets.

The tray 1 can thus be pivoted between the position shown in Fig. 1, in which material fed to the tray discharges at the right hand side (in the drawing) on to one end of a screen S, Fig. 4, which extends below the tray, and a position in which the tray 1 is inclined in the opposite direction, and material discharges at the left hand side and clear of the screen.

Means is provided for manually adjust- ing and releasably locking the tray 1 in at least each of said positions, and one example of such means will now be described.

An upstanding lever S is pivotally attached at its lower end to the left hand end of the tray 1, and passes upwards through a ring or annular lug 7 secured to the superstructure 4. One face of the lever 5 has a plurality if spaced notches or gates 6 which respectively engage the ring 7 in accord ance with the position of the tray 2. The lever 5 is locked in engagement with the ring 7 by a wedge peg 8.

Various other devices for adjusting and locking the tray may alternatively be provided.

The modification shown in Fig. 3 will now be described, parts corresponding to those in Figs. 1 and 2 being indicated by the same reference numerals with the addition of the suffix X.

In Fig. 3, the brackets 3X are provided at their lower ends respectively with lugs 10 which project from the brackets 3X towards the end of the chute 1X to which the lever is attached. Each lug 10 has an upstanding slot 1OA which is open at the top, and the opposed end portions of the shaft 2X engage in the slots 10A. As a result of this modification, the chute 1X can be more easily fitted to the machine during assembly, and can be more easily removed, when necessary.

The tray or chute may be pivotally mounted in any other convenient manner, and the screen may be in the form of a screen conveyor.

Further details of the sifting machine shown in the drawings, and its use in relation to the sifting of drilling mud used in oil drilling, will now be given briefly, mainly with reference to Figs. 1 and 4.

The machine consists generally of the framework 4, on which there is supported by springs 11 a so-called sifting basket 12.

The basket 12 is coupled to a vibratory drive unit 14 which is energised by operation of an actuator unit, not shown. The drive unit 14 functions to shake the basket 12 so that the basket vibrates, preferably elliptically.

The basket 12 has opposed side walls 12A and an end wall 12B. The basket is open at the top and bottom, and the base of the basket is formed by the screen S. As shown in Fig. 4, the screen S is formed by two screen elements Sl which are located side-by-side and are removably clamped in position. The basket 12, at its bottom end.

is reinforced by spaced cross bars 12C ol by an open frame, which, in either case, may be formed integrally with the side walls and end wall.

In use, contaminated mud from a bore hole is fed under pressure of around 40 p.s.i. gauge and at a flow rate of 400 to 1600 gallons per minute into two inlet ducts 20 of the machine. The ducts are each closed at one end and mud forced into the ducts 20 exists therefrom via side pipes 22 into several desilter cones or cyclone separators 23. Sixteen such cones are included in the illustrated machine, though only four can be seen. The pressurized mud enters the cones 23 generally tangentially via the pipes 22 so that a swirling action is generated within the cones.

Owing to centrifugal force, the denser constituents of the contaminated mud, including barite, silt and cuttings, tend to segregate towards the bottoms of the cones 23, while the lighter constituents tend to flow upwardly towards the tops of the cones.

The lighter constituents comprise principally the fluid. Fluid rising to the tops of the cones 23 enters discharge pipes 24 and flows from the machine via discharge ducts 25. The fluid leaving ducts 25 is essentially free of slit and cuttings and can be reformed into mud for recycling to a bore hole being drilled. Approximately 80% of the fluid content of the contaminated mud is separated by the desilter cones 23 from the barite, silt and cuttings for re-use.

The remainder of the mud, comprising about 20% of the originally-present fluid, barite, silt and cuttings is discharged from the bottoms of the cones on to the chute 1. The chute 1 serves to deliver the mud to the upstream end of the basket 12. With the basket vibrating or shaking, fluid and barite in the mud are encouraged to pass through the screens to fall into a collector 30 whence they are removed through an outlet or outlets 31 for reconstitution into drilling mud. Silt and cuttings stay behind on the screen and, due to the vibratory motion, are gradually conveyed to a downstream end of the basket. Upon reaching downstream end, the silt and cutings move on to a discharge lip or chute, not shown, and fall into a receptacle, not shown. The material accumulating in the receptacle is periodically discarded.

The vibratory drive unit 14 consists basically of a driven rotatable shaft 15 which extends transversely of the basket 12, and which has end portions projecting through the side walls 12A and carrying eccentric weights 16. The shaft 15 is housed within a casing 17 secured at its ends to the side walls 12A. The shaft 15 is spaced above the screen elements S1, and below the chute 1, and preferably passes through substantially the centre of gravity of the basket.

The shaft 15 is driven by a hydraulic motor 18 which is co-axial therewith, and is directly coupled to one end thereof. The motor 18 is carried by a casing 19 which is secured to the adjacent wall 12A of the basket, so that the motor is free to vibrate with the basket.

The motor 18 is driven by a power unit, not shown, comprising a pumping system driven by an electric motor, and speed control means, the hydraulic motor 18 being connected to the pumping system by flexible hoses.

The motor 18 may alternatively be a pneumatic motor or an electric motor.

The clamping of one of the screen elements S1 will now be described briefly with reference to Fig. 4, the clamping of the other screen element being effected in the same manner.

The screen element has a rectangular frame of which the side members are of angle-section, one flange projecting horizontally outwards from the vertical flange.

The outer horizontal flange of the frame is clamped between a ledge 36 on the adjacent wall 12A of the basket and a clamping strip 43 which is urged downwards by a spring-loaded plunger 44B.

The inner horizontal flange of the frame is clamped between a runner 48, which is secured to the basket 12 and is located milway between the walls 12A, and a clamping strip in the form of a rectangular-section tube 49. A bolt 51 passes through the tube 49 and the runner 48 and is screwed into a nut 52 secured to the runner 48. The head of the bolt 51 is spaced above the tube 49, and a spring 53 urges the tube 49 upwards.

The plunger 44B and the tube 49 are held in the clamping position shown by a bar, not shown, which extends transversely of the basket and projects through apertures in the side walls 12A.

Fuller details of the machine may be obtained by reference to our co-pending Applications Nos. 49795/76 (Serial No.

1,575,312) and 38083/77 (Serial No. 1,578, 946).

WHAT WE CLAIM IS: - 1. A sifting machine of the kind aforesaid having an improvement consisting in that the tray is pivotally mounted so that it can be pivoted, when required, from the inclined position in which it discharges from said one end thereof on to said one end of the screen, to an oppositely inclined position in which it discharges at its other end clear of the screen, and means is provided for releasably locking the tray in each of said positions.

2. A sifting machine as claimed in Claim 1, in which the tray is pivotally connected to a shaft which has end portions projecting through holes in opposed brackets of the machine, the shaft being secured to the brackets by nuts on said end portions of the shaft.

3. A sifting machine as claimed in Claim 1, in which the tray is pivotally mounted by means of a shaft having end portions engaging in upstanding opentopped slots provided in lugs carried by brackets of the machine.

4. A sifting machine as claimed in Claim 1 or 2 or 3, in which said means for releasably locking the tray comprises an upstanding lever pivotally connected at its lower end to the end of the tray remote from said one end of the screen, a ring through which the lever projects upwardly, a plurality of spaced notches on the lever which are selectively engaged by the ring in accordance with the position to which the tray is pivoted, and a wedge engaging between the ring and the lever on the opposite side of the latter from the notches.

5. A sifting machine as claimed in any one of the preceding Claims for use in sifting drilling mud used in oil drilling, said machine having a plurality of cyclone separators located above the tray and through which mud is supplied to the tray when the machine is in use.

6. A sifting machine as claimed in Claim 1 substantially as hereinbefore described with reference to Figs. 1 and 2 of the accompanying drawings.

7. A sifting machine as claimed in Claim 1, substantially as hereinbefore described with reference to Figs. 1 and 2 of the accompanying drawings, when modified in accordance with Fig. 3.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (7)

**WARNING** start of CLMS field may overlap end of DESC **. The motor 18 may alternatively be a pneumatic motor or an electric motor. The clamping of one of the screen elements S1 will now be described briefly with reference to Fig. 4, the clamping of the other screen element being effected in the same manner. The screen element has a rectangular frame of which the side members are of angle-section, one flange projecting horizontally outwards from the vertical flange. The outer horizontal flange of the frame is clamped between a ledge 36 on the adjacent wall 12A of the basket and a clamping strip 43 which is urged downwards by a spring-loaded plunger 44B. The inner horizontal flange of the frame is clamped between a runner 48, which is secured to the basket 12 and is located milway between the walls 12A, and a clamping strip in the form of a rectangular-section tube 49. A bolt 51 passes through the tube 49 and the runner 48 and is screwed into a nut 52 secured to the runner 48. The head of the bolt 51 is spaced above the tube 49, and a spring 53 urges the tube 49 upwards. The plunger 44B and the tube 49 are held in the clamping position shown by a bar, not shown, which extends transversely of the basket and projects through apertures in the side walls 12A. Fuller details of the machine may be obtained by reference to our co-pending Applications Nos. 49795/76 (Serial No. 1,575,312) and 38083/77 (Serial No. 1,578, 946). WHAT WE CLAIM IS: -

1. A sifting machine of the kind aforesaid having an improvement consisting in that the tray is pivotally mounted so that it can be pivoted, when required, from the inclined position in which it discharges from said one end thereof on to said one end of the screen, to an oppositely inclined position in which it discharges at its other end clear of the screen, and means is provided for releasably locking the tray in each of said positions.

2. A sifting machine as claimed in Claim 1, in which the tray is pivotally connected to a shaft which has end portions projecting through holes in opposed brackets of the machine, the shaft being secured to the brackets by nuts on said end portions of the shaft.

3. A sifting machine as claimed in Claim 1, in which the tray is pivotally mounted by means of a shaft having end portions engaging in upstanding opentopped slots provided in lugs carried by brackets of the machine.

4. A sifting machine as claimed in Claim 1 or 2 or 3, in which said means for releasably locking the tray comprises an upstanding lever pivotally connected at its lower end to the end of the tray remote from said one end of the screen, a ring through which the lever projects upwardly, a plurality of spaced notches on the lever which are selectively engaged by the ring in accordance with the position to which the tray is pivoted, and a wedge engaging between the ring and the lever on the opposite side of the latter from the notches.

5. A sifting machine as claimed in any one of the preceding Claims for use in sifting drilling mud used in oil drilling, said machine having a plurality of cyclone separators located above the tray and through which mud is supplied to the tray when the machine is in use.

6. A sifting machine as claimed in Claim 1 substantially as hereinbefore described with reference to Figs. 1 and 2 of the accompanying drawings.

7. A sifting machine as claimed in Claim 1, substantially as hereinbefore described with reference to Figs. 1 and 2 of the accompanying drawings, when modified in accordance with Fig. 3.