Abstract:
The present invention relates to a novel and highly effective design for the squeegee blades used to remove and collect used cleaning solution and other liquids from substantially flat surfaces in manual and motorized cleaning tools. In comparison to the prior art, the present invention provides the squeegee blade with controlled flexibility so that the blade contacts the surface to be cleaned with a wiping lip area that does not change with the applied pressure. As a result of the constant wiping area provided by this invention, the new squeegee blades can operate efficiently on uneven surfaces with reduced wear. Further, the constant contact area between squeegee blade and the surface to be cleaned provides an excellent sealing action, which in turn, leads to more effective removal of the used cleaning solution from the surface and minimizes losses in vacuum that removes the liquid.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    The present invention concerns a new and improved squeegee blade with markedly superior performance when compared to squeegees based on prior art designs. Squeegee blades are used for cleaning windows, floors, and other flat water-resistant surfaces. They are made from flexible plastic materials, such as natural rubber, synthetic rubber, plasticized polyvinyl chloride, and the like, so that they may easily flex to conform to the surface to be cleaned. In cleaning windows, for example, the squeegee blade is often held in a manually operated hand tool provided with a handle. After a cleaning solution has been sprayed or wiped onto the window, the operator holds the tool by its handle as the squeegee blade is pressed against the window and draws it across the surface. These actions serve to remove the cleaning fluid from the surface and leave the window clean. Similar manual tools also may be used in cleaning floors. In commercial scale operations, however, the squeegee is a component of a motorized cleaning unit. Such units apply a cleaning solution to the floor and, then, clean the wet floor surface by rotating cleaning pads or brushes driven in a circular, reciprocating, or other manner. A set of squeegee blades are mounted on an inverted “U” shaped support bar and drawn behind the cleaning pads. This squeegee assembly collects used cleaning solution within the space under the inverted “U” shaped squeegee blade support bar. The used cleaning solution is removed by vacuum from an opening in the top of the inverted “U” structure and returned to a cleaning solution tank for reapplication in front of the cleaning elements.  
         DESCRIPTION OF THE PRIOR ART  
         [0002]    Conventional squeegee blades have flat rectangular cross sections and are fabricated from natural or synthetic rubbers. Although such squeegee blade profiles have been in use for many years, serious problems arise in their use. These problems become particularly severe in industrial applications where large motorized cleaning equipment is in use.  
           [0003]    In practical applications, there are problems in using the flat rectangular squeegee blades described in the prior art. The rectangular profile that contacts the surface to be cleaned often does not maintain uniform contact with the flat, but slightly irregular, floor surface across the working width of the squeegee blades. This non-uniform surface contact becomes worse as the rectangular edge of the squeegee blades suffers abrasion wear in use. The result is unsightly streaks of used cleaning solution on the floor surface after it has been cleaned. Also, due to abrasion in use, this streaking effect becomes more severe with each use of the manual tool or motorized cleaning machine. In order to minimize this effect, it is necessary to frequently change squeegee blades on motorized or manual cleaning equipment.  
           [0004]    Many buildings, due to age or construction faults, have flooring surfaces that deviate substantially from true flatness. In such cases, conventional prior art squeegee blades cannot conform to provide good floor contact across their width. The result, again, is a streaky effect on the cleaned surface.  
           [0005]    A conventional industrial floor cleaning machine that applies a cleaning solution to the surface to be cleaned, scrubs the floor with the applied cleaning solution, collects the used cleaning solution between two squeegee blades, vacuums up the used cleaning solution from between the squeegee blades, and stores the used cleaning solution for reuse or disposal. This is described briefly by the following paragraphs.  
           [0006]    The squeegee blade support fixture may be in the form of an inverted “U” in cross-section. The squeegee blades are attached to each side of the inverted “U”. This support bar is mounted on a frame attached to the cleaning machine so that it extends transversely across the machine just behind the cleaning brushes or pads. One or more openings are provided in the top of the inverted “U” structure for the attachment of suction hoses to remove used cleaning solution from the space between the two squeegee blades. The cleaning solution removed is transferred to a reservoir that is mounted on the floor-cleaning machine.  
           [0007]    With cleaning machines based on prior art teachings, the lip of the leading, relative to the travel direction of the machine, squeegee blade is serrated across its width. Due to this serration of the squeegee blade on the leading side of the squeegee “U”, cleaning solution can flow under the blade and into the space under the inverted “U”, where it is pulled out through the vacuum lines.  
         SUMMARY OF THE INVENTION  
         [0008]    The present invention provides a novel squeegee blade, which substantially avoids all of the deficiencies, described in the foregoing, that seriously limit the utility of squeegee blades based on prior art teachings.  
           [0009]    [0009]FIGS. 1 through 6, attached hereto, illustrate an embodiment of the present invention in a manual squeegee and contrast it to a manual squeegee based on the teachings of the prior art. The manual squeegee is comprised of a squeegee blade, a support fixture to which the squeegee blade is clamped for support, and a handle attached to the support fixture.  
           [0010]    The squeegee blade,  5  (as numbered in the drawing), contacts the floor surface,  6 , to be cleaned, at an angle of about 45 degrees at the lip,  3 , of the squeegee blade. (FIG. 4)  
           [0011]    When contact force is increased on the squeegee blade,  5 , based on prior art teaching, an increase in the contact area of lip,  7 , results, accompanied by a decrease in the contact force per unit of contact area. (FIG. 5)  
           [0012]    When the contact force is increased between a squeegee blade,  4 , designed according to the present invention, and the surface to be cleaned,  6 , the squeegee blade flexes above the lip,  1 . As a result, the contact area,  2 , between the squeegee blade lip and the surface remains constant, and the contact force, expressed in force per unit of contact area, increases. (FIG. 3)  
           [0013]    As a downward force is applied to the handle of the squeegee based on this invention, the blade itself flexes with the force applied, and the contact area between the lip of the blade,  2 , and the floor remains constant. As a result, the force per unit area between the lip and the floor,  6 , increases. This increased downward force between lip and floor substantially increases the wiping efficiency of the squeegee blade. Furthermore, the added force causes the flexible squeegee blade to conform to any non-uniformities in the floor surface,  6 , more effectively. Consequently, the cleaning solution is wiped more effectively and the streaking observed with prior art squeegees is avoided. Even when the lip area,  2 , becomes worn due the abrasion of repeated uses, the contact area between the squeegee lip and the floor remains substantially constant. (FIG. 3)  
           [0014]    In using the prior art, squeegee blades are often made from low modulus polymer in order to obtain good contact between the squeegee lip and the floor. This approach does reduce streaking initially, but abrasion soon leads to an increase in the contact area, a reduction of contact force, and the appearance of streaks. Freshly installed low modulus squeegee blades, as shown in FIG. 4, generally perform without serious streaking because contact with the floor is at the 90 degree edge of the blade lip,  3 . However, low modulus polymeric material soon is abraded and the contact area increases so that it must be replaced on a regular basis.  
           [0015]    This invention succeeds in obtaining optimum removal of the cleaning solution by designing the squeegee blade so that contact with the floor is on the flat area of the squeegee lip and not with the 90 degree edge of the lip, as is the case with squeegee blades based on the prior art.  
           [0016]    By this invention, the ratio of the thickness of the blade to the radius of curvature at zero stress should be greater than one third of the entire angle of bending before the bending action is half completed.  
           [0017]    The final degree of the bending angle from the initial point, as viewed from the centerline,  41 , should be approximately half the angle of the flexed blade in use. The radius of curvature, R, should be less than 3 times the thickness, T, of the blade. A blade in conformity with the foregoing considerations will have a lip area that will seal well with the floor and wipe so that substantially no streaking remains on the surface to be cleaned. (FIG. 41)  
           [0018]    In the following paragraphs, the use of prior art squeegee blades and squeegee blades based on the new invention in motorized squeegee floor cleaning machines, provided with vacuum systems for removal and recycle of the cleaning solutions, will be compared.  
           [0019]    With squeegees that are based on prior art technology, the leading squeegee blade on the inverted “U” support bar has small protuberances or pads across the face of the lip. This gives the lip a serrated appearance and allows cleaning solution and excessive air to be sucked into the space between the leading and trailing squeegee blades. As a result, even when the squeegee is used on a perfectly flat surface, substantial amounts of air are brought into the space under the inverted “U” support bar along with the cleaning solution. This leads to an excessive lowering of the negative pressure and, thus, vacuum within the space between leading and trailing squeegee blades.  
           [0020]    This deficiency, described in the foregoing, can be corrected by structuring the squeegee on the basis of the current invention. Loss of vacuum within the space between leading and trailing blades is held to a minimum so that cleaning solution with only minimal amounts of air is pulled in under the leading and trailing squeegee blades. Further, negative pressure between blades acts to hold down the trailing squeegee blade and create a dynamic seal between the lip and floor to insure a clean sweep of the used cleaning solution without streaks.  
           [0021]    The current invention can better be understood by reference to the accompanying Figures as described below.  
           [0022]    (1) Squeegee blades on the inverted “U” support bar,  13 , in both the leading,  16 , and trailing,  17 , positions have smooth, non-serrated, contact lips.  
           [0023]    As a result, the leading lip can minimize air entrainment between the blade and floor surface. (FIG. 8)  
           [0024]    (2) In order to increase flexibility near the squeegee blade lip, a row of concavities is provided just above the wiping lip in the backside of the leading squeegee blade,  16 . When squeegee blade,  16 , is mounted on their inverted “U” support bar,  13 , the cavities in the blade face to the inner side of the space between leading,  16 , and trailing,  17 , blades. (FIG. 8)  
           [0025]    (3) The arc,  12 , at the lower end of the trailing squeegee blade,  17 , must face to the inner side of the inverted “U” support bar,  13 . (FIG. 8)  
           [0026]    In operation, a motorized squeegee provided with the novel squeegee blades of this invention, as illustrated in FIGS. 7, 8,  10 , and  11 , performs as described in the following.  
           [0027]    Place the squeegee by the method mentioned (1) on the flat floor,  18 , and start the vacuum pump and scrubbing units of the cleaning machine. Move the machine forward. The forward movement will cause the leading and trailing squeegee blades to flex as shown in FIG. 10. Only minimal amounts of air will leak across the seal made between the flat surface of the squeegee blades and the floor surface. This, in combination with the vacuum pump, causes a negative pressure to increase within the area between the leading,  16 , and trailing,  17 , squeegee blades mounted on the inverted “U”,  13 , support bar. This negative pressure will generate a force, F, between the squeegee blades,  16  and  17 , and the floor,  18 .  
           [0028]    The force, F, is generated by the difference between ambient pressure and the pressure within the space,  14 , within the inverted “U” support bracket. This force, F, in turn, acts to press both squeegee blades against the floor,  18 . Surprisingly, downward force against the floor,  18 , is less at the edge of the leading squeegee blade,  16 , than it is between the floor,  18 , and the edge of the trailing squeegee blade,  17 .  
           [0029]    With regard to (2), it is critically important to carefully select the ratio of cavity area,  11 , to non-cavity area in designing the leading squeegee blade,  16 . If the ratio is too high, it will be too flexible and excessive air will be pulled in with the cleaning solution. This will result in loss of vacuum within the cavity,  14 , under the inverted “U” support bar,  13 . This, in turn, will result in a significant reduction of the force, F, and the seal between squeegee lips,  16  and  17 , and the floor,  18 , will be lost.  
           [0030]    When working on an uneven floor surface, openings will occur between the leading squeegee blade,  16 , and the floor surface. In such cases, there will be a loss of negative pressure within the space,  14 , under the inverted “U” support bar. This loss, however, is not as serious as that observed in the situation described in the foregoing. That is to say that, if the ratio of cavity area to the non cavity area is properly selected, then it is possible to clean floors with considerable unevenness with equipment designed according to this invention. This is because the flexible leading,  16 , and trailing,  17 , squeegee blades conform to nonuniformities in the floor elevation so as to maintain a seal to prevent excessive air leakage and maintain acceptable negative pressures within the space,  14 , enclosed by the inverted “U” support bar.  
           [0031]    According to the teachings of this invention, pressure within the space,  14 , enclosed by the inverted “U” support bar and the squeegee blades can be maintained substantially constant by careful selection of the thickness of the squeegee blades, the modulus of the polymer used in the blades, ratio of the cavity area to non cavity area at the blade lips, and the power of the vacuum pump.  
           [0032]    With regard to point (3), as is the case with the manually operated single blade squeegee mentioned earlier, the trailing squeegee blade lip,  15 , presses down on the floor area,  18 . The trailing squeegee blade,  17 , has a much higher degree of conformability and recovery than do blades designed according to the prior art. Furthermore, the trailing blade,  17 , exerts a much greater downward force against the floor,  18 , due to the action of the leading blade,  16 , in forming a seal against air leakage. (FIG. 10)  
           [0033]    At the point of contact between the lip,  15 , of the trailing squeegee blade,  17 , and the floor, there is substantially no change in the contact area. As a result, the downward force per unit area is equal to the sum of the mechanical pressure of the cleaning machine on the trailing squeegee blade and the pressure resulting from the pressure difference between the space,  14 , enclosed by the inverted “U” support bar and the ambient pressure.  
           [0034]    Because the downward pressure on the floor,  18 , by the rear blade lip,  15 , is high, when the squeegee blade passes over non-uniformities in the floor surface, there is less vacuum loss or streaking than is the case with squeegee blades designed according to the prior art. This is a result of the high degree of conformability of the trailing blade that minimizes the area through which air may flow as the blade passes over non-uniformities. Further, even if some used cleaning solution pooling in the low points of floor non-uniformities is missed by the wiping action of lip,  15 , of the trailing squeegee blade,  17 , it still may be pulled into the space,  14 , enclosed by the inverted “U” squeegee blade support bar by the passage of ambient air under the lip,  15 .  
           [0035]    As a result of the foregoing, it is possible to clean a floor with relatively large non-uniformities without leaving streaks of small puddles when cleaning with a machine that utilizes squeegee blades,  16  and  17 , based on this invention.  
           [0036]    Further, even as the squeegee blades of this invention wear due to abrasion and multiple uses, the area of contact between the trailing squeegee blade lip,  15 , remains substantially constant, so the squeegee blades may be used longer without replacement than is the case with squeegee blades based on the prior art.  
           [0037]    As mentioned in the foregoing, a critical point of this invention is that the design of the leading squeegee blade,  16 , makes it possible to maintain a negative pressure within the space,  14 , within the inverted “U” support bar substantially constant, while still effectively taking in the used cleaning solution.  
           [0038]    It is possible to vacuum in the used cleaning solution without lifting the leading squeegee blade, while keeping a negative pressure in the space within the inverted “U” squeegee blade support bar. How this can be accomplished is described in the following section.  
           [0039]    In order to accomplish the foregoing, the portion of the leading squeegee blade,  16 , at, and just above, the lip,  22 , that contacts the floor is made of a porous material. With this arrangement, cleaning solution can be pulled into the space,  14 , between blades without the need to lift the leading squeegee blade,  16 .  
           [0040]    A plate of a breathable sponge-like material,  20 , and a plate of non-breathable rubber,  21 , can be laminated together to serve as the leading squeegee blade,  22 , with the sponge-like component serving as the floor contact component. (FIG. 12)  
           [0041]    By selection of the degree of breathability of the sponge-like component and the area of the squeegee lip,  22 , the negative pressure in the space,  14 , within the inverted “U” support bar and, as indicated earlier, the pressure of the trailing squeegee blade,  17 , against the floor can be adjusted for optimum performance.  
           [0042]    As described when non-breathable squeegee blades are used, the breathable blades also provide substantially better performance with lower levels of streaking, even on floors with non-uniform surfaces, than can be obtained when using squeegee blades based on prior art teaching.  
           [0043]    It should be mentioned, however, that, if the floor,  23 , to be cleaned is highly uneven, then excessive clearances may develop between the leading blade,  16 , and some areas of the floor,  23 . In such case, it will be difficult to maintain an acceptable level of vacuum within the space between squeegee blades and performance may not be acceptable, even with squeegee blades based on this invention, since the trailing blade,  17 , will not maintain a good seal with the floor,  23 , and used cleaning solution will not be effectively wiped up. (FIG. 15)  
           [0044]    The problem with highly irregular floor surfaces referred to above can be corrected by using a leading squeegee blade,  16 , with a configuration similar to that described for the trailing squeegee blade,  17 . In such case, the leading squeegee blade,  35 , must be mounted so that it is curved in the leading direction. (FIG. 13)  
           [0045]    With the leading squeegee blade,  35 , the flat lip surface will conform to non-uniformities in the floor,  23 , as the blade flexes (FIG. 14), while still maintaining a constant pressure between the lip of the trailing squeegee blade,  17 , and the floor,  23 . Minimal air flow beneath the lip of the trailing squeegee blade as it moves over floor non-uniformities assists in effectively wiping used cleaning solution from the irregular surface. As a result of such performance, even severely irregular floor surfaces,  23 , can be cleaned when squeegee blades based on this invention are used.  
           [0046]    The accompanying drawings are described briefly by the following.  
       
    
    
     BRIEF DESCRIPTION OF THE DROWINGS  
       [0047]    [0047]FIG. 1 is an isometric projection sketch of a single-blade, manually operated squeegee according to this invention.  
         [0048]    [0048]FIG. 2 is a cross sectional view of the squeegee blade and holding clamp for use in the manually operated squeegee of FIG. 1.  
         [0049]    [0049]FIG. 3 is a cross sectional view of a squeegee blade as shown in FIG. 2, when being pulled across a surface to be cleaned.  
         [0050]    [0050]FIG. 4 is a cross sectional view of a manually operated squeegee blade, when it is in use, according to the teachings of the prior art.  
         [0051]    [0051]FIG. 5 is a cross sectional view of a manually operated squeegee blade, when it is in use, based on the prior art.  
         [0052]    [0052]FIG. 6 is a cross sectional view of a prior art manually operated squeegee blade.  
         [0053]    [0053]FIG. 7 is an isometric projection view of a motorized two blade squeegee floor cleaning machine with vacuum lines to the inverted “U” squeegee blade support bar.  
         [0054]    [0054]FIG. 8 is an isometric projection view of leading and trailing squeegee blades of the invention attached to a squeegee blade support frame.  
         [0055]    [0055]FIG. 10 is a cross sectional view of leading and trailing squeegee blades according to the invention mounted on an inverted “U” support bar, as they appear when in use.  
         [0056]    [0056]FIG. 11 is a magnified view of the leading squeegee blade shown in the “A” area of FIG. 10.  
         [0057]    [0057]FIG. 12 is an isometric projection view of leading and trailing squeegee blades of the invention attached to a squeegee blade support frame.  
         [0058]    [0058]FIG. 13 is a cross sectional view of a set of squeegee blades according to the invention that are mounted on an inverted “U” support bar for use on severely uneven floor surfaces.  
         [0059]    [0059]FIG. 14 is an isometric projection view showing the leading blade of a squeegee blade set, designed according to the invention, in contact with a highly uneven floor surface.  
         [0060]    [0060]FIG. 15 is a cross sectional view of a severely uneven floor surface being contacted by a squeegee blade of the invention.  
         [0061]    [0061]FIG. 16 is an isometric projection view of leading and trailing squeegee blades of the invention attached to a squeegee blade support frame.  
         [0062]    [0062]FIG. 17 is an isometric projection view, rotated counter clockwise 90 degrees from FIG. 16, of leading and trailing squeegee blades of the invention attached to a squeegee blade support frame.  
         [0063]    [0063]FIG. 18 is an isometric projection view, rotated 180 degrees from FIG. 16, of leading and trailing squeegee blades of the invention attached to a squeegee blade support frame.  
         [0064]    [0064]FIG. 19 is an isometric projection view, rotated 180 degrees from FIG. 16, of leading and trailing squeegee blades of the invention attached to a squeegee blade support frame.  
         [0065]    [0065]FIG. 20 is an isometric projection view of squeegee blades, according to the invention, that can be used either in the leading or trailing position on the squeegee blade support frame.  
         [0066]    [0066]FIG. 21 is an isometric projection view of squeegee blades, according to the invention, that can be used either in the leading or trailing position on the squeegee blade support frame.  
         [0067]    [0067]FIG. 22 is an isometric projection view of squeegee blades, according to the invention, that can be used either in the leading or trailing position on the squeegee blade support frame.  
         [0068]    [0068]FIG. 23 is an isometric projection view of squeegee blades, according to the invention, that can be used either in the leading or trailing position on the squeegee blade support frame.  
         [0069]    [0069]FIG. 24 is an isometric projection view of squeegee blades, according to the invention, that can be used either in the leading or trailing position on the squeegee blade support frame.  
         [0070]    [0070]FIG. 25 is an isometric projection view of squeegee blades, according to the invention, that can be used either in the leading or trailing position on the squeegee blade support frame.  
         [0071]    [0071]FIG. 26 is an isometric projection view of squeegee blades, according to the invention, that can be used either in the leading or trailing position on the squeegee blade support frame.  
         [0072]    [0072]FIG. 27 is an isometric projection view of a squeegee blade support frame with one leading blade, according to the invention, that is curved just above its lip.  
         [0073]    [0073]FIG. 28 is an isometric projection view of a squeegee blade support frame with one leading blade, according to the invention, that is curved just above its lip.  
         [0074]    [0074]FIG. 29 is an isometric projection view of a squeegee blade support frame with one leading blade, according to the invention, that is curved just above its lip.  
         [0075]    [0075]FIG. 30 is an isometric projection view, rotated 180 degrees from FIG. 28, of a squeegee blade support frame with one leading blade, according to the invention, that is curved just above its lip.  
         [0076]    [0076]FIG. 31 is an isometric projection view, rotated 180 degrees from FIG. 28, of a squeegee blade support frame with one leading blade, according to the invention, that is curved just above its lip.  
         [0077]    [0077]FIG. 32 is an isometric projection view of a squeegee blade support frame with one leading blade, according to the invention, that is curved just above its lip.  
         [0078]    [0078]FIG. 33 is an isometric projection showing a set of squeegee blades, according to the invention, in their support bar mounted on a motorized wet vacuum floor cleaning machine.  
         [0079]    [0079]FIG. 34 is an isometric projection showing a squeegee blade support bar with two identical squeegee blades, having a curve just above the blade lip, according to the invention, that is usable in either the leading or trailing position.  
         [0080]    [0080]FIG. 35 is an isometric projection showing a squeegee blade support bar with two identical squeegee blades, having a curve just above the blade lip, according to the invention, that is usable in either the leading or trailing position.  
         [0081]    [0081]FIG. 36 is an isometric projection showing a squeegee blade support bar with two identical squeegee blades, having a curve just above the blade lip, according to the invention, that is usable in either the leading or trailing position.  
         [0082]    [0082]FIG. 37 is an isometric projection showing a squeegee blade support bar with two identical squeegee blades, having a curve just above the blade lip, according to the invention, that is usable in either the leading or trailing position.  
         [0083]    [0083]FIG. 38 is an isometric projection showing a squeegee blade support bar with two identical squeegee blades, having a curve just above the blade lip, according to the invention, that are usable in either the leading or trailing position.  
         [0084]    [0084]FIG. 39 is an isometric projection showing a squeegee blade support bar with two identical squeegee blades, having a curve just above the blade lip, according to the invention, that is usable in either the leading or trailing position.  
         [0085]    [0085]FIG. 40 is an isometric projection showing a squeegee blade support bar with a trailing squeegee blade having cavities that provided across the outside of the bent area.  
         [0086]    [0086]FIG. 41 is a cross sectional view of a squeegee blade, according to the invention, that illustrates the relationship between the blade&#39;s radius of curvature and thickness to flexing of the blade.  
         [0087]    [0087]FIG. 42 is a cross sectional view of a squeegee blade, according to the invention, that further illustrates the relationship between radius of curvature and thickness to blade flexing.  
         [0088]    [0088]FIG. 43 is a cross sectional view of a squeegee blade, according to the invention, that further illustrates the relationship between radius of curvature and thickness to blade flexing.  
         [0089]    [0089]FIG. 44 is a cross sectional view of a squeegee blade, according to the invention, that further illustrates the relationship between radius of curvature and thickness to blade flexing.  
         [0090]    [0090]FIG. 45 is a cross sectional view of a laminated squeegee blade, according to the invention, that illustrates the relationship between laminate structure and flexing.  
         [0091]    [0091]FIG. 46 is a cross sectional view of a squeegee blade, according to the invention, that can be mounted in either the leading or trailing position on the inverted “U” support bar.  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0092]    The implementation of the current invention is illustrated by the Figures and is further described in the following.  
         [0093]    There are several approaches to flexing a squeegee blade in order to improve its efficiency in wiping used cleaning solution, depending on the specific needs. Several such approaches are described in FIG. 2 and FIG. 9.  
         [0094]    a 1) Reduce the blade thickness from the mounting side to the lip side of the squeegee blade. (FIG. 43)  
         [0095]    a 2) First bend the squeegee blade side opposite to the direction of travel and, then, bend the blade in the direction of travel. (FIG. 45)  
         [0096]    a 3) Bend the squeegee blade to an angle of approximately 90 degrees (FIG. 42). At this point the relation between thickness and the radius of curvature is as follows. The angle θ, made by the centerline,  42 , of the squeegee blade before bending and the centerline after bending,  43 , from thickness centerline  42  before bending and the thickness centerline  43  after bending, is the vertex. From the bending point A to the lip B, AB, is the base of an isosceles triangle. The length of the isosceles triangle&#39;s sides, R, is the radius of curvature.  
         [0097]    a 4) Two squeegee blades are bent near their lips in opposite directions, then, laminated together back to back. A hand squeegee equipped with such a laminated blade can be used in either a forward or backward direction. (FIG. 46)  
         [0098]    a 5) When a blade,  38 , is attached to the back side of bent blade and the bent blade contacts the back blade,  38 , at a point, H, H is the starting point for the bending action. (FIG. 44)  
         [0099]    a 6) The trailing squeegee blade,  17 , of a squeegee that picks up used cleaning solution from the floor by vacuum for recycle can have curvatures at both the upper and lower sides. In such case, if one working side becomes worn, the blade can be reversed so that the other side of the blade comes into use.  
         [0100]    The section that follows describes the use of squeegee blades based on the current invention, for use with motorized floor squeegees that pick up used cleaning solution for recycle by vacuum.  
         [0101]    For optimum operation, airflow under the trailing,  17 , and leading,  16 , squeegee blades must be kept to a minimum in order to avoid a loss of vacuum in the space,  14 . The current invention avoids such losses due to the following considerations:  
         [0102]    A1) One side of the leading blade,  16 , is provided with a series of cavities,  11 , that are faced toward the trailing squeegee blade (FIG. 8). This increases the flexibility of the blade so that it can easily conform to non-uniformities in the floor surface and, thus, minimize air intake.  
         [0103]    A2) Make some thickness differences on one of the two sides of the front blade,  16 , and attach the blade to the squeegee frame,  13 . (FIG. 17). Adjust the point of contact with the floor so that it is under line  26 . The center of the blade where it is thinnest will be slightly off the floor.  
         [0104]    A3) The squeegee blade may be made with differential softness. For example, area,  27 , may be made softer than area,  28 . When this blade is attached to the squeegee frame,  13 , the lower softer area,  27 , can easily conform to the floor surface. (FIG. 16)  
         [0105]    A4) The height of the inverted “U” shaped support frame,  13 , may be adjusted at its attachment point in order to adjust the squeegee blade set level relative to the floor. (FIG. 19)  
         [0106]    A5) The length of the leading squeegee blade may be adjusted at its attachment to the squeegee frame,  13  (FIG. 18). At this time, the contacted point with the floor should be above the line,  32 . The longer part of the leading blade should be slightly above the floor at the center.  
         [0107]    In order to minimize the loss of vacuum within the space under the inverted support bar, the following can be done.  
         [0108]    A6) A breathable sheet of sponge,  20 , is laminated to a non-breathable sheet,  21 , of an elastomeric material. Lengths of the sheets are adjusted so that the breathable sheet,  20 , contacts the floor first. (FIG. 12).  
         [0109]    In addition to the individual actions of the foregoing, combinations of A1) through A6) may be taken together.  
         [0110]    As one example of an embodiment of this invention, the leading squeegee blade, A6), is attached to the main frame,  13 , by, A4), then the lower sponge-like component is first to contact the floor surface.  
         [0111]    When using a motorized floor cleaning machine,  19 , it is possible to have good result when using unidirectional squeegee blades. (FIG. 7)  
         [0112]    If a wet vacuum machine,  34 , is used, however, results are better if dual directional squeegee blades are used. (FIG. 33)  
         [0113]    In the next section, the use of dual directional squeegee blades is described further.  
         [0114]    B1) Dual directional squeegee blades are fabricated by laminating a trailing blade,  17 , as in A1), with a leading blade,  16 . The laminated blades then are mounted in both the leading and trailing positions on the inverted “U” support bar of the squeegee frame,  13 . (FIG. 20)  
         [0115]    B2) The rear blade,  17 , and the above mentioned A2), the front blade, put together, and these blades attach on the rear and front sides of the squeegee frame,  13 . Careful adjustments should be made so that the laminate contacts the floor below the line,  26 . (FIG. 24).  
         [0116]    B3) The trailing squeegee blade,  17 , as in above mentioned A3), laminated with a leading blade,  16 , is attached to the squeegee frame,  13 . (FIG. 22)  
         [0117]    B4) After the height of the perpendicular part,  29 , is adjusted on the squeegee frame, the trailing blade,  17 , is attached to the front and rear part of the squeegee frame,  13 . (FIG. 23)  
         [0118]    B5) The trailing blade,  17 , as in abovementioned A5) and the leading blade,  16 , are laminated and attached to the front and rear plates of the squeegee frame,  13 . The floor contact point must be adjusted so that it is above the line,  32 . (FIG. 25),  
         [0119]    B6) The laminate of trailing blade,  17 , with the sponge-like material,  20 , is mounted onto the front and the rear plates of the squeegee frame,  13 . (FIG. 21)  
         [0120]    B7) The blade,  34 , which has multiple cavities near its lip and starting at the bend of the trailing blade,  17 , also may be mounted on both the back and front plates of the squeegee frame,  13 . (FIG. 26)  
         [0121]    When the squeegee equipment is operated unidirectionally, combinations of B1) through B7), depending on the application, may be used.  
         [0122]    In cleaning severely uneven floors,  23 , utilizing A1) through A6) of the foregoing, the trailing squeegee,  17 , wipes cleanly since both trailing,  17 , and leading,  35 , squeegee blades maintain good seals between lips and the uneven floors so as to minimize excessive loss of vacuum.  
         [0123]    C1) On one side the blade is bent to the lower area of the front blade,  35 , to put the cavities,  11 , on the lower side. This area of the blade should be on the inside of the blade. The leading squeegee blade,  35 , must be mounted so that it is curved in the leading direction. (FIG. 27)  
         [0124]    C2) On one side the blade is bent to the lower area of the front blade,  35 , to make some thickness differences on one of the two sides of the front blade,  35 . Adjust the point of contact with the floor so that it is under line  26 . The leading squeegee blade,  35 , must be mounted so that it is curved in the leading direction. (FIG. 30)  
         [0125]    C3) On one side the blade is bent to the lower area of the front blade,  35 , to be made with differential softness. The leading squeegee blade,  35 , must be mounted so that it is curved in the leading direction. (FIG. 29)  
         [0126]    C4) The height of the inverted “U” shaped support frame,  29 , may be adjusted at its attachment point in order to adjust the squeegee blade,  35 , level relative to the floor. The leading squeegee blade,  35 , must be mounted so that it is curved in the leading direction. (FIG. 32)  
         [0127]    C5) The length of the leading squeegee blade,  35 , may be adjusted in length to the bent down part as it is mounted on the squeegee frame,  13 . In making length adjustments, the floor contact point must be kept above the line,  32 . The leading squeegee blade,  35 , must be mounted so that it is curved in the leading direction. (FIG. 31)  
         [0128]    C6) The breathable sponge-like side,  20 , laminated with a non-breathable side,  21 , to form a squeegee blade is curved at the bottom and attached to the squeegee blade support frame,  13 . The leading squeegee blade,  35 , must be mounted so that it is curved in the leading direction. (FIG. 28)  
         [0129]    Further, in order to make a squeegee blade set operable in a forward/backward direction, approaches B1) through B6) mentioned in the foregoing may be used.  
         [0130]    D1) A trailing blade,  17 , as described in C1) of the foregoing, and a leading blade,  35 , may be laminated together, and mounted on the inverted “U” squeegee blade support bar,  13 , in both the leading and trailing positions. (FIG. 34)  
         [0131]    D2) A trailing blade,  17 , as described in C2) of the foregoing, and a leading blade,  35 , may be laminated together, and mounted on the inverted “U” squeegee blade support bar,  13 , in both the leading and trailing positions. (FIG. 35)  
         [0132]    D3) A trailing blade,  17 , as described in C3) of the foregoing, and a leading blade,  35 , may be laminated together, and mounted on the inverted “U” squeegee blade support bar,  13 , in both the leading and trailing positions. (FIG. 36)  
         [0133]    D4) The height of the inverted “U” shaped support frame,  29 , may be adjusted at its attachment point in order to adjust the level relative to the floor. A trailing blade,  17 , as described in C4) of the foregoing, and a leading blade,  35 , may be laminated together, and mounted on the inverted “U” squeegee blade support bar,  13 , in both the leading and trailing positions. (FIG. 38)  
         [0134]    D5) A trailing blade,  17 , as described in C5) of the foregoing, and a leading blade,  35 , may be laminated together, and mounted on the inverted “U” squeegee blade support bar,  13 , in both the leading and trailing positions. (FIG. 37)  
         [0135]    D6) A trailing blade,  17 , as described in C5) of the foregoing, and a leading blade,  35 , may be laminated together, and mounted on the inverted “U” squeegee blade support bar,  13 , in both the leading and trailing positions. (FIG. 39)  
         [0136]    Examples of the forces acting on the rear blade,  17 , in a squeegee set designed according to this invention are given in the following.  
         [0137]    The width of the wiping area of the squeegee blade set is 100 cm and the length of the trailing blade,  17 , from the base,  25 , of the inverted “U” bar support to the surface to be cleaned,  15 , is 2 cm. At that point the weight between lip and floor is measured as 2000 g.  
         [0138]    The leading squeegee blade,  16 , supports a vacuum at 20 cm of water within the space,  14 , under the inverted “U” support bar. With this information, it is possible to calculate the force of the trailing blade on the floor surface caused by the difference in the air pressure;  
         [0139]    The total downward force, resulting from air pressure difference, on the trailing blade,  17 , is then: 
         FT=100 cm×2 cm×20 g/cm  2 =4000 g 
         [0140]    If the force directed to the floor is half of FT, then, The increase of the downward force on the floor from the differential air pressure is Fl=2000 g  
         [0141]    As can be seen from the foregoing equation, the force from the trailing blade tip area,  15 , is doubled by the difference in air pressure. The negative pressure within the space under the inverted “U” of the squeegee blade support bar,  14 , is normally about 100 mm of water, and the pressure, F, under the lip area,  15 , of the trailing squeegee blade becomes higher with increases in this negative pressure. However, if airflow slows down and the air pressure differential diminishes, the speed of the cleaning machine must be decreased on an uneven floor in order to wipe cleanly without water streaks.  
         [0142]    When the negative pressure within the space under the inverted “U” support bar becomes higher, the air flow becomes faster due to pressure differential. In this case, wiping will be without streaks. If there is less airflow through the vacuum hose,  24 , however, there will be a need to decrease the inner diameter of the hose in order to keep the air velocity constant for effective removal of the used cleaning solution.  
         [0143]    Depending on the power of the machine, at negative pressure of 1000 mm of water in the space,  14 , under the inverted “U” squeegee blade support bar and a vacuum hose,  24 , diameter of 20 mm provides an acceptable velocity for removal of the used cleaning solution and its transfer to the storage vessel.  
         [0144]    A closer spacing of the leading and trailing squeegee blades will result in a more rapid removal of the used cleaning solution by the collecting hose,  24 .  
         [0145]    There is a limit to how close the blades can be spaced, since, if flat sides actually contact each other, space under the inverted “U” becomes substantially zero and all flow halts. If use is made of approach A1) with the leading blade as C1, then, even if the inner curved blades touch at rest, they will separate apart as the cleaning machine moves on the floor surface. When cavities have been provided across the outside of the bent area of the trailing squeegee blade,  40 , (FIG. 40), then as indicated earlier, there is sufficient space between the blades for them to separate easily as the cleaning machine moves across the floor surface. Spacing the leading and trailing blades close together results in a minimal area between blades. This, in turn, leads to a fast and efficient removal of the used cleaning solution by the vacuum hose,  24 . The amount of the used cleaning solution and air taken in under the leading blade must be carefully adjusted so that more comes in under the ends of the blade and less under the center section.  
         [0146]    The general configuration of the trailing blade,  17 , is shown in FIG. 10. For optimum performance, the lip thickness, radius of curvature, and length from the inverted “U” bar to the lip of this blade must be selected in accordance with the negative pressure used within the area,  14 , under the inverted “U” support bar.