GB2124510A

GB2124510A - Liquid filtration apparatus

Info

Publication number: GB2124510A
Application number: GB08017770A
Authority: GB
Inventors: Robert Osteen Alexander
Original assignee: Cera International Ltd
Current assignee: Cera International Ltd
Priority date: 1979-05-31
Filing date: 1980-05-30
Publication date: 1984-02-22

Abstract

Liquid filtration apparatus for machine tool-coolant comprises a liquid collecting tank (10) with a rotary drum filter and an endless chain drag conveyor (15) located in it. The drum is mounted between a pair of sprockets (23 and 24) round which the conveyor chains extend so as to be enclosed within the volume of the conveyor and rotated by the conveyor drive motor. The drum comprises an inner perforated steel layer and an outer layer (33) of woven metal mesh. A row of liquid jet nozzles (44) within the drum direct liquid jets at the inner surface of the cylindrical wall, to wash off solids separated by the mesh from liquid flowing into the drum. The conveyor then moves the solids along and up the tank floor to a discharge station. <IMAGE>

Description

SPECIFICATION Liquid filtration apparatus This invention relates to liquid filtration apparatus for removing solids, including fine particles of solid matter, from liquid collected from at least one industrial machine for re-use.

U.S. Patent Specification No. 3,784,017 discloses gas washing apparatus including a liquid collecting tank with a rotary drum filter and a drag conveyor located in it, the drag conveyor being below the drum filter. An elongated liquid jet is located within the drum and is oriented to direct liquid in jet form at the interior of the perforated surface of the drum whereby to displace enmeshed particles from the perforated wall of the drum. An outside scraper blade or rotating bush is provided for removing displaced particles so that they fall from the drum from displacement from the tank by the drag conveyor.

One object of this invention is to provide selfcontained liquid filtration apparatus which is designed to be connected into the liquid coolant/lubricant circulating system of a separate conventional machine tool and to be operated to separate solid mater from the liquid coolant/lubricant used in that machine tool. To this end it is desirable for the overall height of the filtration apparatus to be minimised so that it can be simply installed alongside the conventional machine tool with which it is to be used having regard to the fact that the used coolant/lubricant liquid outlet is usually located near the base of conventional machine tools.

Another object of this invention is to provide means effective to transport away from the drum metal powder of the fine particulate type that is produced by grinding.

Briefly filtration apparatus in which this invention is embodied includes a liquid collecting tank with a rotary drum filter and a drag conveyor located in it, the drag conveyor comprising endless conveying means, wherein the rotary drum filter is located within the space that is enclosed by the endless conveying means.

Preferably the rotary drum filter is driven for rotation about its own axis by the drag conveyor.

The preferred form of drag conveyor comprises a pair of endless chains or the like which run on pairs of coaxial rollers or sprockets. It is especially convenient for the drum of the rotary drum filter to be mounted between such a coaxial pair of rollers or sprockets in the manner of an axle so that the drum rotates with the rollers or sprockets, since the overall height of the apparatus is minimised.

It is preferred that the filter media of the rotary drum filter be incorporated in the cylindrical wall of the drum, in which case means may be provided for dislodging matter deposited onto the outer surface of the filter media and for displacing that matter to the conveyor. The matter dislodging means may be arranged so that matter so dislodged falls onto a drag conveyor run that extends therebelow. Preferably said means comprise liquid jet forming means for directing liquid at the filter media from within the drum conveniently at a velocity which is high compared with the velocity of liquid that is drawn into the drum for re-use.

Apparatus in which this invention is embodied and which is designed for use in conjunction with a grinding machine includes, outside the drum, a receptacle having a slot which is aligned with a part of the filter media onto which jets are directed by the jet forming means, and suction means adapted to suck liquid into the receptacle through the slot so that particulate matter dislodged from the drum by the action of the jets is drawn into the receptacle with such liquid, there being discharge means by which liquid and particulate matter drawn into the receptacle by the suction means is discharged onto the drag conveyor. Preferably the jet forming means that direct liquid jets onto said part of the filter media are orientated so that the jets they direct are directed substantially horizontally towards said slot.

Machine tool coolant filtration apparatus in which this invention is embodied will be described now by way of example with reference to the accompanying drawings, of which:~ Figure 1 is diagrammatic side elevation of the apparatus; Figure 2 is a section on the line Il-Il in Figure 1 of a practical embodiment and is drawn to a larger scale than is Figure 1; Figure 3 is a diagram illustrating the configuration of the drag conveyor in the tank of the apparatus shown in Figures 1 and 2 and is drawn to a somewhat smaller scale than are Figures 1 and 2; Figure 4 is a fragmentary longitudinal section Or a modified form of the apparatus shown in Figures 1 to 3, the section being in a vertical plane; ard Figure 5 is a plan view of Figure 5.

The apparatus shown in Figures 1 to 3 comprises an open topped tank 10 which is generally rectangular and has an upwardly sloping extended portion 11 at one end, as is shown in Figures 1 and 3. Figure 3 shows that an inlet duct 12 is provided at the top of the main portion of the tank 10. The inlet duct 12 is for connection to the used coolant discharge of the machine tool or tools with which the apparatus is used.

A drag conveyor is housed within the tank 10 and comprises an endless conveyor 13 and a power plant 14. The construction of the endless conveyor 13 is conventional, comprising a pair of endless chains which are interconnected at spaced intervals by lengths 1 5 of angle iron. The chains run on sprockets or rollers which are arranged so that the path of the endless conveyor 13 turns around a coaxial pair of intermediate rollers or sprockets 16 from a lowermost horizontal portion 17 to an upwardly inclined portion 18 which extends up to an upper pair of coaxial driven sprockets 19. The driven sprockets 19 are journaled in the upwardly sloping extension 1 1 of the tank 10 at a level which is higher than the level of the inlet duct 1 2.The path of the endless conveyor 13 also comprises a curved return portion 21 which runs downwards from the driven sprockets 19 under a curved guide 22 to a coaxial pair of end idler sprockets 23 and 24.

Those parts of the endless conveyor 13 that pass around the end idler sprockets 23 and 24 and along the lower horizontal path portion 17 and the upwardly inclined path portion 18 are spaced by a substantially uniform distance from the adjacent surfaces of the tank 10. The lengths 15 of angle iron form pushers which project outwardly from the chains and pass close to the inner surfaces of the tank 10 as they travel around the end idler sprockets 23 and 24, along the horizontal path portion 17 and up the upwardly inclined path portion 18.

Figure 1 shows that the power plane 14 is mounted at the top of the upwardly sloping extension 11 of the tank 10. The power plant 14, which includes an electric motor, has a sprocket 25 mounted on its output shaft. The coaxial pair of driven sprockets 19 have a common axle which projects through the tank wall and carries a further sprocket 26 outside the tank 10. The power plant sprocket 25 is drivingly coupled to the further sprocket 26, and hence indirectly to the driven sprockets 19, by a drive chain 27 which meshes with the further sprocket 26.

Figure 2 shows that each of the end idler sprockets 23 and 24 is journaled in the adjacent wall of the tank 10 and that they form the end walls of a cylindrical drum which has a perforated cylindrical wall 28. It follows that the drum is located within the space that is enclosed by the endless conveyor 13.

The cylindrical wall 28 of the drum comprises a laminated tube with a ring 29, 31 spigotted into it at either end. Each ring 29, 31 is welded to both the laminated tube and the inner face of the respective end idler sprocket 23, 24 with which it is coaxial. There is a radial clearance between the laminated tube and the lengths of chain of the endless conveyor 13 that extend around the sprockets 23 and 24.

The laminated tube has two layers. The inner layer 32 is a perforated stainless steel tube and provides the laminated tube with its structural strength. The outer layer 33 comprises a woven metal mesh and conveniently is formed by wrapping a length of such mesh around the stainless steel tubular layer 32 and joining the ends of the mesh length together to form a joint that runs along the laminated tube.

The end idler sprocket 23 is annular. It is journaled in a tube 34 which is a sliding fit in an aperture 35 in the wall of the tank 10. The outer end of the tube 34 is welded to a hollow housing.

The bore of the tube 34 communicates with the interior of the hollow housing 36 through an aperture in the wall of the housing 36 to which the tube 34 is welded. The housing 36 is bolted to a mounting ring 37 which in turn is welded to the outer surface of the tank 10 around the aperture 35. An outlet port 38 is formed in the side wall of the housing 36.

A manifold 39 is supported within the interior of the drum by its header pipe 41 which extends through the central aperture of the annular end idler sprocket 23, through the tube 34, through the interior of the hollow housing 36 and through an aperture 42 in an end wall 43 of the housing 36. The header pipe 41 is welded to the housing end wall 43 around the outer end of the aperture 42. The housing end wall 43 is bolted to the remainder of the structure of the housing 36.

Hence the header pipe 41 and the manifold 39 that it carries are supported removably by the hollow housing 36. The axis of the header pipe 36 is horizontal and extends directly below the rotary axis of the drum. The end of the header pipe 41 within the drum is closed. The manifold 39 depends from the header pipe 41 and carries a row of downwardly directed jet nozzles 44 which are adapted to form flat divergent jets which are directed vertically downwards onto the interior of the perforated mild steel tube 32. The spacing between the jet nozzles 44 is such that the jets formed by adjacent nozzles 44 merge before striking the perforated mild steel tube 32, as is shown diagrammatically in Figure 2.

Figure 1 shows that the housing outlet port 38 is connected to the inlet of a motor driven pump 45 by a pipe 46. A pump outlet pipe 47 is provided for returning filtered coolant to the machine tool or machine tools with which the apparatus is used. A branch pipe 43 from the pump outlet pipe 47 is connected to the outer end of the header pipe 41.

In use of the apparatus, used coolant is delivered from the associated machine tool or machine tools to the tank 10 through the inlet duct 12. It will be understood that the level of such coolant within the tank 10 is maintained below the inlet duct 12 and above the top of the drum.

The motor of the power plant 14 is energised so that the endless conveyor 13 is driven continuously anti-clockwise as seen in Figure 3.

The pump motor is energised so that the pump 45 is driven continuously to draw coolant liquid from within the drum, and to discharge that liquid via the pump outlet pipe 47 to the associated machine tool or machine tools and to deliver some of it to the manifold 49 via the branch pipe 48 and the header pipe 41.

Heavy solids, such as swarf or soils, that are carried into the tank 10 by the incoming flow of coolant, sink onto the conveyor 13 and are dragged out of the liquid by the length of the conveyor 13 that moves up the upwardly inclined portion 18 of its path to a discharge location at the top. Finer particulate matter carried into the tank 13 10 by the incoming coolant flow is carried to the drum by the flow of liquid that is drawn into the drum from outside, through the interstices of the cylindrical wall 28, by the action of the pump 45 drawing liquid from within the drum. Such particulate matter is deposited on the outer surface of the cylindrical wall 38, and it tends to be deposited nearer the top than the bottom of the cylindrical wall.The cylindrical wall 28 is rotated about its axis by the sprockets 23 and 24 that form its end walls, those sprockets being driven by the chains of the conveyor 1 3. Hence particulate matter deposited on the cylindrical wall 28 is carried to the bottom of the drum where it is dislodged by the action of the liquid jets directed onto the inner surface of the bottom of the drum by the row of nozzles 44. Such dislodged particulate matter falls onto the conveyor 1 3 that runs below the drum and is dragged out of the liquid by that conveyor 13.

The pump 14 is arranged so that the velocity at which liquid is directed onto the interior of the drum by the nozzles 44 is considerably greater than the velocity at which liquid is drawn into the drum through the interstices of the cylindrical wall 28 of the drum. Hence any tendency for particulate matter that is dislodged from the drum to be sucked back onto the drum with liquid flow into the drum is minimized.

Supply of liquid to the header pipe 41 may be controlled so that liquid is directed by the jets 44 onto the interior of the cylindrical wall 28 periodically and not continuously. A solenoid valve may be provided in the branch pipe 48 for controlling liquid supply to the header pipe 41.

Operation of the solenoid valve could be controlled automatically and a suitable control circuit may include a timing device.

The flow rate at which the apparatus delivers filtered liquid depends upon the axial length of the drum. Reinforcement rings can be provided within the laminated tube at spaced intervals along that tube if necessary. Such rings should be located between adjacent jets 44 if they are required, otherwise they could undesirably influence the operation of the jets 44 to dislodge particulate matter from the drum.

Figures 3 and 4 show another arrangement for dislodging fine particulate matter from the outer surface of the cylindrical wall 28 and for transferring it to the drag conveyor 13 for conveyance out of the tank 10. This arrangement is particularly suitable for dislodging from the drum metal powder of the fine particulate type that is produced by grinding.

In this arrangement the header pipe 41 supports a manifold 49 within the drum in a manner similar to the manner in which it supports the manifold 39. The manifold 49 projects sideways from the header pipe 41, in the direction towards the upwardly sloping run of the conveyor 13, and carries a row of horizontally directed jet nozzles 51 which are adapted to form flat divergent jets which are directed horizontally onto the interior of the perforated mild steel tube 32.

The spacing between the jet nozzles 51 is such that the jets formed by adjacent nozzles merge before striking the perforated mild steel tube 32, as is shown diagrammatically in Figure 5.

Another motor driven pump 52, which is referred to from hereon as the transfer pump 52 and which is mounted outside the tank 10 adjacent the pump 45, has its inlet connected to an elongate manifold casing 53 via a suction pipe 54 which passes through the tank wall. The manifold casing 53 is supported within the tank 10 between the drum and the upwardly sloping run of the conveyor 13 and adjacent the drum. A horizontally extending elongate slot communicates with the interior of the manifold casing 53, and hence with the interior of the suction pipe 54, and is formed in the face of the casing 53 that is adjacent the drum so that it is horizontally aligned with the axis of rotation of the drum and with the portion of the interior of the perforated mild steel tube 32 onto which the jets are directed by the jet nozzles 51.The slot is virtually as long as the perforated tube 32 and has flow directing baffles located in it at spaced intervals along it A discharge pipe 55 is connected to the output of the transfer pump 52 and discharges onto the upwardly sloping run of the conveyor 13.

Particulate matter dislodged from the drum by the action of liquid jets directed horizontally onto the inner surface of the perforated tube 32 by the jet nozzles 51 is drawn through the elongate slot into the manifold 53 by the action of the transfer pump 52 and is then transferred by that pump 52 to the discharge pipe 55 from which it is discharged onto the upwardly sloping run of the conveyor 13.

Apparatus as described with reference to the drawings is particularly convenient for use with machine tools which have a low outlet for used coolant liquid (say 2 feet from the ground) since it avoids the need for special civil engineering work for its installation.

Liquid filtration apparatus similar to that described above with reference to the accompanying drawings may be used in washing fluid collecting tanks of industrial parts washing machines and air washers.

It should be noted that formation of the cylindrical wall 28 as a laminated tube composed of the inner perforated layer which provides structural strength and the outer woven metal mesh enables a finely woven metal mesh to be used as the filter media material with the consequent advantage of a high degree of fine solid separation whereas such finely woven metal mesh material cannot be used along to form the cylindrical wall because it does not have sufficient inherent structural strength. The inner perforated layer may be formed of a coarse wire mesh material.

Claims

1. Liquid filtration apparatus including a liquid collecting tank with a rotary drum filter and a drag conveyor located in it, the drag conveyor comprising endless conveying means, wherein the rotary drum filter is located within the space that is enclosed by the endless conveying means.

2. Liquid filtration apparatus according to Claim 1, wherein the rotary drum filter is driven for rotation about its own axis by the drag conveyor.

3. Liquid filtration apparatus according to Claim 1, in which the drag conveyor comprises a pair of endless chains which run on at least one pair of coaxial sprockets, wherein the drum of the rotary drum filter is mounted in the manner of an axle between said pair of coaxial sprockets so that the drum rotates with the sprockets of said pair.

4. Liquid filtration apparatus according to any one of Claims 1 to 3 wherein the filter media of the rotary drum filter is incorporated in the cylindrical wall of the drum.

5. Liquid filtration apparatus according to Claim 4, including means operable to dislodge matter deposited onto the filter media and to displace that matter to the conveyor.

6. Liquid filtration apparatus according to Claim 5, wherein said matter dislodging means comprise liquid jet forming means operable to direct liquid at the filter media from within the drum.

7. Liquid filtration apparatus according to Claim 6, wherein said liquid jet forming means and said means operable to draw liquid into the drum through the filter media are arranged so that the former directs liquid in jet form at the filter media at a velocity which is higher than the velocity of liquid that is drawn into the drum by the latter.

8. Liquid filtration apparatus according to Claim 6 or Claim 7, including outside the drum a receptacle having a slot which is aligned with a part of the filter media onto which jets are directed by the jet forming means, and suction means adapted to suck liquid into the receptacle through the slot so that particulate matter dislodged from the filter media by the action of the jets is drawn into the receptacle with such liquid, there being discharge means operable to discharge onto the drag conveyor liquid and particulate matter drawn into the receptacle by the suction means.

9. Liquid filtration apparatus according to Claim 8, wherein the jet forming means are oriented so that the jets they direct are directed substantially horizontally towards said slot.

10. Liquid filtration apparatus including a liquid collecting tank with a rotary drum filter in it, the drum filter comprising a cylindrical drum having a cylindrical wall, filter media incorporated in the cylindrical wall and means operable to draw liquid into the drum from within the tank and through the filter media, there being matter dislodging means comprising liquid jet forming means operable to direct liquid in jet form at the filter media from within the drum in opposition to liquid drawn into the drum, the matter dislodging means being provided for displacing from the filter media matter deposited onto the filter media, wherein there are provided, outside the drum, a receptacle having an aperture which is aligned with a part of the filter media onto which liquid is directed in jet form by the jet forming means, and suction means operable to suck liquid into the receptacle through the aperture so that particulate matter dislodged from the filter media by the jets is drawn into the receptacle with such liquid, there being discharge means by which liquid and particulate matter drawn into the receptacle by the suction means is discharged at a location remote from the drum.

11. Liquid filtration apparatus according to Claim 10, wherein said liquid jet forming means and said means operable to draw liquid into the drum through the filter media are arranged so that the former directs liquid in jet form at the filter media at a velocity which is higher than the velocity of liquid that is drawn into the drum by the latter.

12. Liquid filtration apparatus according to Claim 10 or Claim 11, wherein the jet forming means are oriented so that liquid they direct in jet form is directed substantially horizontally towards said aperture.

13. Liquid filtration apparatus according to any one of Claims 10 to 12, including a drag conveyor comprising endless conveying means having a run which extends below the drum.

14. Liquid filtration apparatus including a liquid collecting tank with a rotary drum filter in it, the drum filter comprising a cylindrical drum having a perforated cylindrical wall and means operable to draw liquid into the drum from within the tank through the perforated wall, wherein the perforated cylindrical wall comprises a laminated tube composed of an inner structural layer of perforated material and an outer layer of woven mesh filter media material laid on the inner layer.

15. Liquid filtration apparatus substantially as described hereinbefore with reference to and as illustrated in Figures 1 to 3 of the accompanying drawings or modified substantially as described hereinbefore with reference to and as illustrated in Figures 4 and 5 of the accompanying drawings.