Abstract:
A skimming apparatus which skims a two-component liquid from the surface of a liquid mixture in a tank includes a pump which pumps the skimmed liquid to a coalescer for separating and collecting a lower density liquid component from the mixture and returning the rest of the liquid to the tank. The skimming apparatus further includes a skimmer which is designed to float on the surface of the liquid mixture in the tank. Arms extend between the skimmer and a mounting assembly so that as the level of the liquid mixture in the tank changes the skimmer will continue to skim from the surface of the liquid mixture. A self-adjusting tube assembly extends between the skimmer and the mounting assembly.

Description:
FIELD OF THE INVENTION  
         [0001]    This invention relates generally to removing a nonsoluble oil from an aqueous solution used as a coolant in a machining environment. More particularly, this invention relates to a skimmer which removes a quantity of liquid mixture from the surface of the liquid mixture inside a tank containing the mixture and pumps the mixture to a coalescer which separates the tramp oil from the aqueous solution and returns the aqueous solution to the tank so that the useful life of the aqueous solution may be prolonged.  
         BACKGROUND OF THE INVENTION  
         [0002]    In many machining operations, an aqueous coolant is sprayed or flowed at the location where a cutting tool engages the workpiece, for lubrication and cooling purposes. The coolant is then collected in a tank located below the machine and recycled for continuous use for as long as possible.  
           [0003]    Aqueous coolants of this type are fairly expensive, so it is advantageous to maintain such aqueous coolants in usable condition for as long as possible. Typical machining operations also include lubricating oil for lubricating movable parts. Eventually, this oil drips or flows into the aqueous coolant tank, where it floats upon the surface of the aqueous coolant due to its lighter weight and lower density. This oil, referred to as “tramp oil,” will eventually also contribute to bacterial growth within the aqueous coolant, resulting in a foul odor and reducing the useful life of the aqueous coolant.  
           [0004]    Due to environmental concerns, the oil-contaminated aqueous coolant must be treated as hazardous waste, and therefore represents an environmental and economic concern. Thus, tramp oil represents a serious environmental and economic problem with respect to maintaining proper and cost effective aqueous coolant use during machining operations.  
           [0005]    A number of skimming devices have been developed over the years to remove tramp oil from the surface of aqueous coolant in a coolant tank for a machine. Disk skimmers include a disk which extends into the aqueous coolant and into contact with the tramp oil. Rotation of the disk near the surface results in removal of some oil from the surface, whereupon it is scraped by a blade and removed. Belt type skimmers involve an endless belt which removes tramp oil from the surface of the aqueous coolant, whereupon it is also scraped therefrom for removal. Disk and belt skimmers of this type are relatively inefficient and have space limitations for proper mounting and operation.  
           [0006]    Floating tube skimmers and weir-type skimmers adapt to liquid level fluctuations, and they generally include a pump for pumping the skimmed liquid to a separation device. Such skimmers have proved to be acceptable in relatively large bodies such as lakes, ponds, rivers or even oceans. However, their size typically prevents their use in machining applications. In machining operations, most coolant tanks are as shallow as five or six inches, or as deep as several feet. Also, some machining coolant tanks are located in relatively inaccessible places without much spare space located adjacent thereto.  
           [0007]    In summary, in machining operations it is necessary to skim primarily tramp oil from the surface of the aqueous coolant in the tank (though the skimmed liquid will also include some coolant), to deliver the tramp oil coolant mixture to a separation unit, to separate the tramp oil from the aqueous coolant for collection, and to return the aqueous coolant to the tank for reuse.  
           [0008]    Applicant&#39;s U.S. Pat. No. 5,601,705 discloses a two-part system including a skimmer located inside a tank containing a liquid mixture and a coalescer located outside the tank. The skimmer skims the liquid mixture from the surface of the liquid mixture inside the tank. The coalescer includes a pump which pumps the skimmed fluid through a hose from the skimmer to the coalescer. The coalescer separates tramp oil from the mixture and returns “cleaned” coolant to the tank. Although U.S. Pat. No. 5,601,705 discloses one configuration or design of coalescer, the coalescer may take numerous configurations such as the one disclosed in applicant&#39;s U.S. Pat. No. 6,056,128.  
           [0009]    Although the skimmer disclosed in U.S. Pat. No. 5,601,705 functions effectively, it has numerous parts which must be assembled in a certain manner, which is very time-consuming. Therefore, some may consider it too expensive to manufacture and too difficult to maintain in the event one or more parts fails.  
           [0010]    Therefore, It is an object of this invention to reduce the number of parts of an aqueous coolant skimmer, specifically the number of moving parts and to simplify the manufacture of such a skimmer.  
           [0011]    It is another object of this invention to improve access to the parts of an aqueous coolant skimmer, to make it easier maintain, without sacrificing the primary functional features of applicant&#39;s prior devices.  
           [0012]    It is another object of this invention to enable the purchaser of an aqueous coolant skimmer to repair the skimmer including replacing the pump without sending the skimmer back to the manufacturer for repair.  
           [0013]    It is still another object of the invention to achieve the above-noted objects for a variety of differently sized and shaped tanks for collecting and holding aqueous coolant.  
         SUMMARY OF THE INVENTION  
         [0014]    The present invention achieves the above-stated objects by utilizing a floatable skimmer which floatably adjusts to the level of the liquid mixture in the tank while at the same time skimming liquid from adjacent the surface, a bracket located at a fixed vertical level in the tank and operatively connected to a vacuum source, and an outlet tube which conveys skimmed liquid from the skimmer to the pump due to the application of vacuum from the vacuum source, the outlet tube adapted to accommodate relative vertical movement between the floatable skimmer and the bracket.  
           [0015]    Another aspect of the invention further contemplates a pair of spaced arms or connectors, each being pivotably connected at both ends, to the bracket and to the skimmer. These connectors assure stable relative vertical movement between the floatable skimmer and the bracket as the liquid level in the tank fluctuates up and down. These connectors also maintain a desired distance between the skimmer and the bracket.  
           [0016]    The invention also contemplates, as the vacuum source, the use of a submersible pump located along an outflow line or conduit. The pump preferably mounts to the bracket and the outflow conduit resides in fluid communication with one end of the outlet tube. Thus, the apparatus pumps skimmed liquid from the supply container, through the outlet tube, along the outflow conduit and eventually to a coalescer.  
           [0017]    The skimmer includes an open-top supply container with a variably sized inlet which adjusts in response to level liquid within the supply container, the supply container further having an outlet adjacent a bottom thereof, which is in fluid communication with one end of the flexible outlet tube. An adjuster residing within the open-top supply container floatably adjusts the size of the inlet in response to the level of the liquid within the supply container, so that the variation of the flow rate of the pump produces a corresponding change in the size of the cross sectional area of the inlet to the supply container. More specifically, an increase in the flow rate of the pump causes the adjuster to correspondingly increase the size of the inlet, while a decrease in the flow rate of the pump causes a corresponding decrease in the size of the inlet.  
           [0018]    Overall, compared to applicant&#39;s prior skimmer, the present invention significantly reduces the number of parts. This reduction in the number of components also simplifies the overall construction. Moreover, because of its inventive structure, the parts are simpler in construction, and the parts are more accessible for an operator, and thereby easier to maintain and/or replace.  
           [0019]    If the pump is mounted directly to the bracket, the pump resides immediately adjacent the skimming apparatus and within the tank. This arrangement helps to further simplify the overall construction of the coalescer, which is typically mounted to a nearby wall. Nevertheless, while a preferred embodiment the present invention contemplates a submersible pump connected directly to the bracket located in the coolant tank, it is to be understood that the pump could be located anywhere along the fluid connection between the outlet tube and the coalescer, so long as sufficient fluid pressure is maintained in the fluid line connection therebetween.  
           [0020]    In an alternative embodiment of the present invention, the skimming apparatus is not secured to a tank wall. Rather, the skimming apparatus is secured to a support float which rises and lowers with the level of fluid inside the tank. This embodiment is preferably used inside deep tanks but may be used in any size of tank.  
           [0021]    These and other features of the invention will be more readily understood in view of the following detailed description and the drawings. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0022]    [0022]FIG. 1 is a perspective view of a preferred embodiment of the skimming apparatus of the present invention mounted inside a tank containing a liquid mixture.  
         [0023]    [0023]FIG. 2 is a side elevational view, partially cut away, of the skimming apparatus of FIG. 1.  
         [0024]    [0024]FIG. 3 is a side elevational view, partially cut away, of the skimming apparatus of FIG. 1 with the skimmer raised relative to its position illustrated in FIG. 2.  
         [0025]    [0025]FIG. 4 a top plan view of the skimming apparatus of the present invention.  
         [0026]    [0026]FIG. 5 is a view taken along the line  5 - 5  of FIG. 2.  
         [0027]    [0027]FIG. 6 is an exploded view of the tube assembly shown in FIGS.  1 - 5 .  
         [0028]    [0028]FIG. 7 a perspective view of the skimming apparatus of the present invention secured to a support float. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0029]    The drawings, and particularly FIG. 1, illustrate a skimming apparatus  10  for skimming a liquid mixture of at least two liquid components from inside a tank  12  containing the mixture. The skimming apparatus  10  also pumps the skimmed fluid to an external location where the liquid components of the mixture are separated from one another and one of the components is returned to the tank  12 .  
         [0030]    The tank  12  has a bottom  16  and four side walls  18 , only one of which is shown in FIG. 1. Although FIG. 1 illustrates a generally rectangular tank  12  containing the liquid mixture, the tank  12  may be other configurations such as circular or oval. One of the advantages of the present invention is that the skimming apparatus  10  may be quickly and easily mounted at different locations inside any number of different tanks.  
         [0031]    The tank  12  is typically made of metal such as steel, but may be made of numerous other materials as well.  
         [0032]    The liquid mixture is typically a water-based coolant into which some quantity of machine tool lubricating oil inevitably leaks. Reference numeral  20  identifies the liquid level inside the tank  12 . In a machining environment, the liquid level  20  may vary in height ranging as low as 5 inches to as high as several feet. The liquid level  20  may be of any height depending upon the size of the tank and the volume of the liquid mixture.  
         [0033]    The skimming apparatus  10  is secured to the tank  12  with a mounting assembly  22 . (see FIG. 2) The mounting assembly  22  comprises a mounting bracket  24  and a magnet housing  26  inside which is located a magnet (not shown). Due to the metallic nature of the tank side wall  18 , the mounting assembly may be secured to one of the side walls  18  of the tank  12  at any desired location and held at such a location due to the magnetic force of the magnet and the tank side wall  18 .  
         [0034]    As illustrated in FIG. 4 in plan view, the mounting bracket  24  is a generally L-shaped cross section comprising a first portion  28  oriented parallel wall  18  and a second portion  30  extending inwardly from the first portion  28  at a right angle i.e. away from the illustrated wall. The first and second portions  28 ,  30  extend generally perpendicular to one another and form a generally L-shaped cross sectional configuration (See FIG. 4). The second portion  30  of the mounting bracket  24  has a generally rectangular cut-out portion  32  which functions as a handle for the entire skimming apparatus  10 . (see FIG. 2) The handle enables a user to transport the skimming apparatus  10  from one location to another quickly and easily without disassembly.  
         [0035]    The mounting bracket  24  is preferably made of plastic, and more particularly polyvinylchloride or PVC. The magnet housing  26  is preferably made of metal, but may be made of other materials, and is secured to the mounting bracket  24  with a screw or other fastener (not shown).  
         [0036]    As best illustrated in FIG. 4, a pump  34  is secured to the second portion  30  of the mounting bracket  24  and located on one side thereof. Any standard pump will function in the present invention. However, one which has proven satisfactory is manufactured by the Little Giant Pump Company of Oklahoma City, Okla., and is designated Model No. 1EA-42. Such a pump is a submersible centrifugal style pump which is capable of pumping 170 gal./hr. An electric cord  36  (see FIG. 2) which may be plugged into a outlet energizes or activates the pump  34 .  
         [0037]    An outflow conduit  38  adapted to convey fluid extends upwardly and outwardly from the pump  34  as illustrated in FIGS.  1 - 3 . This conduit or flexible tube  38  leads to a coalescer such as the one disclosed in applicant&#39;s U.S. Pat. No. 6,056,128 where one liquid component of the liquid mixture is separated from another liquid component of the mixture due to their different densities. The conduit  38  is preferably a hose but may be a tube or any other type of structure through which fluid can flow in the direction of arrow  40 . As illustrated in FIGS. 3 and 4, a conventional hose clamp  42  comprising a collar  44  and a screw  46  secures the conduit  38  to the pump  34 , but any one of a number of other suitable fastening structures may be used.  
         [0038]    The skimming apparatus  10  includes a floating skimmer  48  which skims the liquid mixture from the surface of the liquid inside the tank. As best illustrated in FIGS. 1 and 4, the skimmer  48  comprises a horizontally oriented bottom  50 , a vertically oriented first or front wall  52  and a vertically oriented second or rear wall  54  generally parallel the front wall and spaced apart therefrom. Each of the front and rear walls  52 , 54  has a central portion  56  and a pair of outwardly extending outer portions  58 .  
         [0039]    A pair of floats  60  and  62  extend between the outer portions  58  of the front and rear walls  52 ,  54 . The floats  60 ,  62  are adapted to float on the upper surface of the liquid mixture and prevent the skimmer  48  from sinking to the bottom of the tank  12 . The floats  60 ,  62  are secured to the front wall  52 , extend rearwardly from the front wall  52  through the rear wall  54  of the skimmer and continue rearwardly therefrom. One of the floats  60  is of a length shorter than the other float  62  in order to properly balance the skimmer  48  on the surface of the liquid mixture and as to not interfere with the pump  34 . The weight of the skimmer  48  is heavier on one side due to a tube assembly which will be described below, causing the assembly to roll to one side. The difference in the length of the floats offsets this weight differential.  
         [0040]    As best illustrated in FIG. 5, each of the floats  60 ,  62  is a tube filled with air. Each of the floats  60 ,  62  has an outer surface  64  and an inner surface  66 , the difference between the inner and outer surfaces comprising the thickness of the float wall. At the rearward end of each of the floats  60 , 62 , the tube is covered with a cap  68  in order to prevent liquid from getting inside the interior of the floats. As illustrated in FIG. 5, the upper surface of the liquid mixture is located approximately half way up the height of the floats  60 ,  62  or located at the midpoint of the floats  60 ,  62 . The floats  60 ,  62  are preferably made of plastic, and more particularly polyvinylchloride or PVC, but may be made of other materials.  
         [0041]    As best illustrated in FIGS. 1 and 5, the skimmer  48  further comprises a pair of spaced side walls  70  which extend between the front and rear walls  52 ,  54  above the bottom  50 . Together, the bottom  50 , front and rear walls  52 ,  54  and side walls  70  define an supply container  72  of the skimmer  48  which is adapted to receive and hold a quantity of the liquid mixture skimmed from the upper surface of the liquid mixture inside the tank. As illustrated in FIG. 5, one of the side walls  70  has a hole or outlet  74  therethrough. As illustrated in FIGS. 1 and 5, the front wall  56  of the skimmer  48  has an inlet  76  defined by a cutout through which the liquid mixture flows (see arrows  78 ) into the supply container  72 .  
         [0042]    As illustrated in FIGS. 1 and 5, an adjuster  80  located inside the supply container  72  regulates the flow of the liquid mixture through the inlet  76 . As illustrated in FIG. 4, the adjuster  80  comprises a front bracket or wall  82  and a rear bracket or wall  84  between which extends a float  86  adapted to float on the surface of the liquid mixture inside the supply container. The float  86  is a tube filled with air but may be other structures of different shapes or sizes. The front bracket  82  has a front surface  88  which abuts against a rear surface  90  of the front wall  52  of the skimmer. As illustrated in FIG. 4, a biaser  89  pushes the adjuster forwardly toward the front wall  52  of the assembly. More specifically the biaser  89  extends between the rear bracket  84  of the adjuster  80  and the rear wall  54  of the skimmer  48 . Although the biaser  89  is illustrated as being a spring, it may be any other biasing device.  
         [0043]    As illustrated in FIG. 5, the adjuster  80  is pivotable about a horizontal axis defined by a rod  92  extending between the front and rear walls  52 ,  54  of the skimmer  48 . As the float  86  moves up and down with the level  95  of skimmed liquid located inside the supply container  72 , the adjuster  80  pivots about the horizontal axis. The interaction or contact of the front surface  88  of the front bracket  82  of the adjuster  80  and the rear surface  90  of the front wall  52  of the skimmer  48  removes debris therebetween by creating a wiping action and helps prevent the inlet  76  from becoming clogged.  
         [0044]    As illustrated in FIGS. 1 and 4, a stop  91  extends into the supply container  72  and limits upward movement of the adjuster  80  by contacting an upper surface  93  of the rear bracket  84 . Although the stop  91  is illustrated as being a screw, it may be other structures. Thus, the pivoting motion of the adjuster  80  inside the supply container  72  ensures proper operation of the skimming apparatus  10 . When the pump  34  is shut down or turned off, fluid in tube  38  flows down the tube  38  which causes the supply container  72  to fill up with the back flow. As the supply container  72  fills with fluid, the adjuster  80  rises until it hits stop  91 . The rising of the adjuster  80  closes the inlet  76  which keeps oil which was just skimmed from being pushed out of the supply container  72  through the inlet  76  into the tank  12 . The front bracket or wall  82  of the adjuster  80  has a top edge  93  which is higher than the fluid in the tank  12  when the pump is off, creating a damming effect and completely shutting off the inlet  76 .  
         [0045]    As illustrated in FIGS. 1 and 5, a removable screen  94  having a top portion  96  extends downwardly into the interior of the supply container  72 . This removable screen  94  functions to screen debris from the liquid mixture inside the supply container  72  before the liquid mixture passes through the hole  74  in one of the side walls  70  of the supply container. Although the removable screen  94  is preferably a wire screen, it may be made of plastic or any other type of material. The top portion  96  enables the removable screen  94  to be easily grasped by a user for removal.  
         [0046]    As illustrated in FIG. 4, the mounting assembly  48  further comprises a pair of extensions  98  extending rearwardly from the rear wall  54  of the skimmer. Each of these extensions  98  is vertically oriented and has a pair of holes  100  therethrough (see FIGS. 2 and 3).  
         [0047]    A pair of articulating pivot arms or connectors  102  extend between the mounting assembly  48  and the mounting bracket  24  of the mounting assembly  22 . These pivot arms  102  are pivotably secured to the mounting bracket  24  with fasteners  104 , which are illustrated as being screws but which may be any other type of fastener. The other end of the pivot arms  102  are secured to the extensions  98  of the mounting assembly  48  with fasteners  106  as illustrated in FIG. 4. These pivot arms  102  allow the skimmer  48  to move vertically inside the tank  12  with the level of the liquid mixture without affecting the operation of the pump or affecting the mounting assembly. Thus, the skimmer may move from a down position illustrated in FIG. 2 to an up position illustrated in FIG. 3. The downward movement of the skimmer  48  is limited by a limiter  108  which extends through the second portion  30  of the mounting bracket  24 . The limiter  108  is illustrated in the drawings as being a screw but may be any other structure which limits downward movement of the pivot arms  102 . This limiter  108  engages the lower pivot arm  102  and prevents the pivot arms from moving further downwardly beyond the down position illustrated in FIG. 2.  
         [0048]    Another principal component of the skimming apparatus  10  of the present invention is a tube assembly or outlet tube  110 . The tube assembly  110  extends between the skimmer  48  and the pump  34 . The parts of the tube assembly  110  are illustrated in FIG. 6 and comprise a first tube  112  and second tube  114  adapted to slide inside the interior of the first tube  112 . The first tube  112  has a hole  116  therethrough into which is inserted a coupling  118  having a female threaded end  1   19  adapted to engage a male threaded end  120  of the pump  34  and secure thereto. Similarly, the second tube  114  has a hole  122  therein which is adapted to receive a coupling  124  having a male threaded end  126  which is adapted to be threadably engage the hole  74  of one of the side walls  70  of the skimmer  48 . As illustrated in FIG. 6, a collar  128  surrounds the first tube  112 , and similarly a collar  130  surrounds the second tube  114 . Caps  132  cover the ends of the first and second tubes  112 , 114  of the tube assembly.  
         [0049]    The configuration of the tube assembly allows the tubes to move telescopically relative to one another as the skimming apparatus moves up and down with variations in the level of fluid inside the tank. The skimmed mixture which flows into the supply container  72  of the skimmer  48  and through the hole  74  in the side wall  70  flows into the tube assembly  110  via the coupling  124  through the tubes and is drawn through the coupling  118  by the operation of the pump. The second tube  114  slides inside the first tube  112  allowing the entire tube assembly to lengthen and shorten as necessary.  
         [0050]    As illustrated in FIG. 1, a sleeve  134  extends between the tube pieces and prevents material and debris from entering the space between the tubes and inhibiting their movement relative to one another. The ends of the sleeve may be coated with a sealant to prevent the sleeve from fraying. The sleeve  134  may be made of fiberglass or nylon. Bands  136  illustrated in FIG. 1 secure the ends of the sleeve  134  inside the collars  128  and  130 , thus securing the fiberglass sleeve  134  to the first and second tubes  112 ,  114 .  
         [0051]    The second tube  114  has a ribbed portion  138  which prevents debris and other materials from jamming the second tube inside the first tube and preventing movement of the tubes relative to one another. The ribbed portion  138  comprises ribs  140  between which are grooves  142 . The ribbed portion  138  of the second tube  114  enhances the movement of the second tube  114  inside the first tube  112  and enhances the relative movement thereof.  
         [0052]    [0052]FIG. 7 illustrates an alternative embodiment of the present invention. In this embodiment a single support float  150  is used to support the skimming apparatus  10 , the support float being adapted to rise and fall with the liquid level inside the tank. The support float  150  has a metal bracket  152  secured thereto. The magnet  27  of the mounting assembly  22  is secured to the metal bracket  152  in order to secure the skimming apparatus  10  to the support float. Other method or devices may be used to secure the skimming apparatus  10  to the support float  150 .  
         [0053]    As illustrated in FIG. 7, the support float  150  is preferably made of multiple pieces of plastic polyvinylchloride (PVC) pipe  154  secured together. End caps  156  cover the ends of the outermost pieces of pipe. A pair of support feet  158  covered at their lower ends with end caps  160  raise the support float  150  off the bottom of the tank  12  when the liquid level inside the tank drops below a certain level. Although a specific configuration of support float  150  is illustrated and described, those skilled in the art will appreciate that other configurations of a support float may be used. In addition, other materials may be used to construct the support float  150  and feet  158 .  
         [0054]    In operation, upon activation of the pump  34 , the adjuster  80  inside the supply container  72  of the skimmer  48  is drawn downwardly due to the suction or vacuum drawn by the pump  34  on the fluid inside the supply container  72 . This downward motion of the adjuster  80  increases the size of the inlet  76  integrally formed in the front wall  56  of the skimmer  48 . Fluid flows through the inlet  76  into the supply container  72  and is pulled via the pump  34  through the hole  74  in the side wall  70  of the supply container  72  into the tube assembly  110 , and up through the tube assembly  110  into the pump  34 . The pump  34  then pumps the liquid mixture through an outlet tube  38  to a coalescer or other separator (not shown) located outside the tank  12  which removes “tramp” oil from the aqueous coolant. The cleaned aqueous coolant is then returned to the tank  12  for reuse.  
         [0055]    The pump  34  is connected to a timer (not shown) which performs an on/off cycle often. Cycling helps the coalescer separate the oil in a more efficient manner. The cycling also helps create the wiper action described above.  
         [0056]    While these and other features of the skimming apparatus in accordance with the preferred embodiment of the present invention have been described, it will be understood that the invention is not limited thereby and, in light of the present disclosure, various other alternative embodiments will be apparent to one of ordinary skill in the art without departing from the scope of the invention. For example, the invention may be used with different types of floats in order to float the skimmer of the present invention. Accordingly, applicant intends to be bound only by the following claims.