Liquid purification or separation – With repair or assembling means
Reexamination Certificate
2000-09-12
2002-03-12
Lithgow, Thomas M. (Department: 1724)
Liquid purification or separation
With repair or assembling means
C210S295000, C210S298000, C210S411000, C210S415000, C210S460000, C210S416500, C210S462000
Reexamination Certificate
active
06355167
ABSTRACT:
FIELD OF INVENTION
This invention relates to an apparatus for filtering contaminated liquids, particularly cooling and/or lubricating liquids which are employed during the machining of workpieces with metal removal, comprising a liquid container with an inlet for contaminated liquid and an outflow for filtered liquid, in which container a filtering insert is disposed which can be connected to the outflow.
BACKGROUND OF INVENTION
Apparatuses of this type, which are also sometimes termed sieve separators, are employed during the machining of workpieces with metal removal for the conditioning of cooling and lubricating liquids which are used in grinding, turning, milling, etc, and which have to be freed from material swarf and dust as extensively as possible before they can be reused as cooling lubricants. Contaminated liquid reaches the liquid container via the inlet and is taken off as purified liquid via the outflow after it has flowed through the filtering insert, which retains swarf and dust from the liquid. The separated contaminants can be automatically removed by means of an extractor device. If the amount of contaminants which arise is small, it is also possible for the liquid to be discharged from the filtering apparatus and for the sludge which has accumulated over the course of time to be removed by hand.
An apparatus of the type cited at the outset is known from DE 196 35 364 A1, in which a bar screen is disposed in the liquid container as a filtering insert, the inlet side of which is directed downwards, wherein the scraper chain of a scraper conveyor is led past the inlet side of the bar screen in order to clean the bar screen. In this known apparatus, the area of the bar screen through which the liquid can flow during filtration is limited and is restricted by the length and width of the liquid container. Since the space taken up by filtering apparatuses in the vicinity of machine tools should be designed to be as small as possible, and a compact mode of construction of the filtering apparatus is therefore required, this known apparatus is in most cases unsuitable for full-flow filtration, in which the entire liquid is filtered at a constant degree of fineness. Consequently, it is generally only used for partial flow filtration in which only part of the liquid is finely filtered through the bar screen using an aperture width of 50 &mgr;m or 75 &mgr;m, whilst the remainder of the liquid to be purified is deemed to be satisfactory with somewhat inferior degree of filtration which can be achieved via a further, coarser filter, or which can be achieved by means of a stack of plates which results in calming of the flow, as a result of which contaminants which are entrained in suspension are able to settle in the contaminated liquid.
For throughputs comprising larger amounts of liquid which have to be finely filtered by full-flow filtration, apparatuses are known in which a filtering insert which rotates about a horizontal axis is disposed immersed in the liquid. The contaminated liquid flows into the interior of the drum through a filter means disposed at the periphery of the filtering insert and is discharged via a suction pipe connected to the insert. At least one scraper is disposed in the container parallel to the axis of rotation of the drum and is pressed against the insert, and when the scraper rotates it removes contaminants which have been deposited on the filter means. These contaminants then sink downwards in the liquid container and are removed from the container by a rake apparatus.
In this known apparatus for full-flow fine filtration, the discharge of the filtrate from the interior of the filtering insert frequently causes problems, since the suction pipe is led via a rotary lead-through into the interior of the filter, which is difficult to seal from the contaminated liquid. In this known apparatus, only a comparatively small pressure difference can be employed between the interior of the filter and the liquid on the outside thereof, so that intermediate storage of the filtrate in a filtrate tank directly behind the filtering insert is necessary. From the filtrate tank, the filtrate can be fed back to the machine tool or the like by means of feed pumps. In this known apparatus it has proved particularly difficult to install and remove the filtering insert. These are operations which have to be carried out at regular intervals in order to subject the filter to a thorough cleaning procedure if contaminants which have not been removed by the scraper have blocked the filter means of the insert over the course of time.
SUMMARY OF THE INVENTION
The object of the present invention is to improve an apparatus of the type cited at the outset so that a high throughput of liquid through the filtering insert is achieved for an apparatus of comparatively small external dimensions, wherein it should be possible to take off the filtrate directly from the liquid container without additional filtrate collecting vessels, and wherein it should be possible in addition to ensure reliable cleaning of the filtering insert in operation, and to ensure ease of replacement of the filtering insert.
This object is achieved according to the invention by providing a filtering insert which substantially consists of a filter drum which can be installed in the liquid container fixed in relation thereto and which comprises a filter means which is disposed at its periphery and which can be cleaned by a cleaning device which can be moved along the peripheral face of the drum. The filter drum is preferably cylindrical and is disposed suspended or standing on an end face in the liquid container, and can be inserted therein from above and can be removed from the container from above.
The use of a filter drum at the periphery of which the filter means is disposed results in a large filter area which is sufficient even for high liquid throughputs. Since the filter drum itself does not rotate in the liquid container, but is fixedly disposed in relation thereto, the costly rotary lead-through which was used in the prior art between the interior of the filter drum and the take-off pipe for the filtrate can be dispensed with. Instead, it is possible to attach and seal the pipe for the filtrate fixedly to the filter drum by a flange or by another means, and to remove the filtrate directly from the interior of the filter drum by means of a feed pump. A relatively large pressure drop can thereby be achieved between the outside and the inside of the filter, which results in a high throughput through the available filter area.
Since the filter drum can be removed from the container from above, and can be inserted in the latter from above, the liquid of the liquid container does not need to be discharged when the filter drum is replaced, so that the down-time of the apparatus when changing the drum can be kept to a minimum. The drum can be replaced within a few minutes, by detaching it from the flanged joint to the feed pump, pulling it upwards from the container together with part of the suction line, and replacing it by a new drum, which then only has to be flanged to the feed pump before it can be put in operation. Outflow of the filtrate advantageously occurs via a filtrate suction pipe which projects into the drum interior and which is sealed by an end face of the filter drum. At the same time, the arrangement can be designed so that the filter drum is disposed suspended on the filtrate outflow, and so that no additional fixing means are therefore necessary for the fixed mounting thereof in the interior of the liquid container.
The filter drum can have a discharge opening on its bottom end face, which discharge opening can be opened or closed from the top end face. In order to remove the filter drum, which is necessary for the replacement thereof or for a thorough cleaning operation, the discharge opening on the bottom end face can be opened from the top face of the drum, so that any filtrate which still remains in the interior of the drum can drain downwards therefrom when the drum is lifted upward
Lithgow Thomas M.
MSG Maschinen-und Stahlbau GmbH
Vickers Daniels & Young
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