Abstract:
A method of manufacturing interlocking sheet metal floor members for use in a grain storage bin or like application requiring passage of fluid through the floor members without permitting passage of granular material therethrough. The method comprises the steps of forming a first interlocking section on a first side edge of a strip of sheet metal and a second interlocking section on a second side of the strip of sheet metal; shearing, opening and corrugating the strip of sheet metal in one roll forming stand which utilizes a pair of shearing and corrugation rollers, wherein the shearing step includes shearing rows of slits across a width of a central portion of the strip of sheet metal, wherein the opening step includes opening the slits to permit fluid flow therethrough, and wherein the corrugating step includes corrugating the strip of sheet metal along each of the series of the slits; and cutting the strip of sheet metal at selected transverse locations to form the sheet metal floor members. The first interlocking section of one sheet metal floor member is interlockable with the second interlocking section of another sheet metal floor member.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to a floor system for a grain storage bin or like application, and, more particularly, to a method and apparatus for making a floor system for grain storage bins utilizing interlocking, ventilated, sheet-metal floor members. 
     Sheet-metal grain storage bins are used for both short term and long term storage of a wide variety of different grains. Grain storage bins of this type ordinarily include a sheet-metal housing, an elevated perforated sheet-metal floor, and a fan for blowing air into the space below the floor so that the air flows upwardly through the floor into the grain. The floor is made up of a plurality of elongated perforated floor members of generally channel-like cross-sectional configuration which interlock with each other to form a continuous floor. The floor may be supported on a variety of different kinds of support members. Usually, the support members are free standing sheet-metal support legs. Examples of grain bin flooring systems of this general kind are described in Simmons U.S. Pat. No. 4,418,558, and Trumper U.S. Pat. No. 4,137,682. 
     Floor members for grain storage bins are typically constructed using a roll forming machine. A strip of sheet metal having prefabricated ventilation holes drilled or punched therein is then fed into the machine from a roll stock. The prefabricated strip with ventilation holes therein is then fed through a preforming stand for making the interlocking side sections. Next, the strip is fed through a corrugation stand to form the corrugations in association with the prefabricated ventilation holes. Finally, the strip is fed through a final forming stand for arching or crowning the top surface of the floor to increase the strength of the floor because the removal of material for the ventilation slots weakens the material. There are several disadvantages with this method which include the added step of drilling or punching the ventilation holes or the extra cost of purchasing pre-punched strip sheet metal, the disposal of the wasted material from the drilling or punching of the ventilation holes, the loss of strength in the floor due to the removal of material to form the ventilation holes, and the added fabrication step of having to arch or crown the top of the floor to compensate for the loss in strength. 
     The Simmons U.S. Pat. No. 4,418,558 teaches a method of manufacturing a grain bin sheet metal floor which includes processing a continuous roll of sheet metal through a preliminary shaping stand for making the interlocking side walls, a lancing stand for making closed slits in the sheet metal a corrugation stand separate from the lancing stand for opening the slits and forming corrugations in the sheet metal, and a finishing stand for arching the floor member. A cut-off machine then cuts the continuous sheet metal into the desired lengths constituting the individual floor members. This method still has the disadvantage of having separate stations for lancing and corrugating the material. 
     SUMMARY OF THE INVENTION 
     The present invention defines an improved method of manufacturing interlocking sheet metal floor members for use in a grain storage bin or like application requiring passage of fluid through the floor members without permitting passage of granular material therethrough. The method comprises the steps of forming a first interlocking section on a first side edge of a strip of sheet metal and a second interlocking section on a second side of the strip of sheet metal. The next step is shearing, opening and corrugating the strip of sheet metal in one roll forming stand using one set of rollers, wherein the shearing step includes shearing rows of slits across a width of a central portion of the strip of sheet metal, wherein the opening step includes opening the slits to permit fluid flow therethrough, and wherein the corrugating step includes corrugating the strip of sheet metal along each of the series of the slits. The final step is cutting the strip of sheet metal at selected transverse locations to form the sheet metal floor members. The first interlocking section of one sheet metal floor member is interlockable with the second interlocking section of another sheet metal floor member. 
     The present invention provides a shearing and corrugation stand for a continuous roll forming machine for use in making sheet metal floor members. The shearing and corrugation stand comprises a first roller and a second roller. The first roller has a plurality of shear blades each of which is arranged transversely and parallel to each other around a periphery of the first roller. Each of the plurality of shear blades having a first side section and a second side section. The first and second side sections each have recesses therein to form shearing teeth for cutting slits in the sheet metal. The shearing teeth of the first and second side sections are alternately displaced with respect to each other so that a tooth on one section is opposite a recess of the other section. The second roller has a plurality of shear blades each of which is arranged transversely and parallel to each other around a periphery of the second roller. Each of the plurality of shear blades has a first side section, and a second side section. The first and second side sections each have recesses therein to form shearing teeth for cutting slits in the sheet metal. The shearing teeth of the first and second side sections are alternately displaced with respect to each other so that a tooth on one section is opposite a recess of the other section. The shearing blades of the first roller are arranged to mesh with the shearing blades of the second roller to cut and open slits in the sheet metal and at the same time form corrugations in the sheet metal. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a prospective view of a segment of a typical floor member for use in a grain storage bin or like application, the floor member being manufactured in accordance with the method and apparatus of the present invention. 
     FIG. 2 is a schematic block diagram illustrating a roll forming machine which performs the basic steps of manufacturing a floor member in accordance with the present invention. 
     FIG. 3 is a sectional drawing illustrating the slitting, opening and corrugation of the sheet-metal in a single stage of the roll forming machine in accordance with the present invention. 
     FIG. 4 is a prospective view of the rollers used in the slitting, opening and corrugation stage shown in FIG.  3 . 
     FIG.  5   a  is a side elevation of shear/corrugation blade for use in a first roller according to the present invention. 
     FIG.  5   b  is a top plan view of the blade shown in FIG.  5   a.    
     FIG.  5   c  is an end view of the blade shown in FIG.  5   a.    
     FIG.  6   a  is a side elevational view of a shear/corrugation blade of a second roller according to the present invention. 
     FIG.  6   b  is a top plan view of the blade shown in FIG.  6   a.    
     FIG.  6   c  is an end view of the blade shown in FIG.  6   a.   
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 1 illustrates one end segment of a floor member  10  manufactured in accordance with the method and apparatus of the present invention. The floor member  10 , which may be of any desired length, includes a central floor surface portion  12  formed integrally with a depending male support channel  16  at one side of the floor member  10  and a depending female support channel  14  at the opposite side of the floor member  10 . When the floor is installed, the male support channel  16  of the floor member fits into the female support channel  14  of an adjacent similar floor member and both are engaged by a free-standing sheet-metal floor support (not shown) that maintains an air space or plenum below the floor. The free standing floor support is well known to those having ordinary skill in the art. 
     The central floor surface portion  12  of the floor member  10  is preferably of horizontal construction, and includes a multiplicity of narrow ventilation slots  20 . The central portion of the floor member is also formed in a series of transverse corrugations having peaks  22  and valleys  24 . The corrugations extend parallel to the direction of the slots  20 . In a preferred construction, as illustrated, the ventilation slots  20  are located intermediate of the corrugations peaks  22  and valleys  24 , or in other words on the slopes of the corrugations, but it is not essential that this alignment be preserved throughout the floor member  10 . 
     The floor member  10  is formed of sheet-metal which is preferably a galvanized sheet-steel. Typically, the stock from which floor member  10  is fabricated comprises galvanized sheet-steel having a thickness of approximately 0.038 to 0.039 inch. This material is strong enough for most applications. Of course, a heavy or lighter sheet-metal stock may be employed, depending upon end use requirements. 
     FIG. 2 illustrates a roll forming machine  26  according to the present invention for use in fabricating the floor member  10  utilizing a continuous roll of sheet-metal. Flat sheet-metal stock is fed as a strip  28  from a roll  30  in a roll storage station  32  into a preliminary forming stands  34  of the roll forming machine  26 . The preliminary forming stands  34  are used to shape the support channels  14  and  16  along the edges of the sheet-metal strip  28 . 
     As strip  28  emerges from the preliminary forming stands  34 , the strip  28  retains a flat central portion that will ultimately form the central floor surface portion  12  of a completed floor member  10  (see FIG.  1 ). In this condition the sheet-metal strip  28  is fed into the shearing and corrugating stand  40  in accordance with the present invention. The shearing and corrugation stand  40  uses a pair of rollers or drums  42  and  44  (shown in FIGS. 3 and 4 and discussed below), each of which has blades which shear and open the ventilation slots  20  and at the same time provides the corrugation on the central floor surface portion  12  of the floor member  10 . The shape of the blades (as further explained below) allows the strip  28  to simultaneously be formed into the corrugations while the ventilation slots  20  are cut and opened. As the completely formed floor member strip  28  emerges from the shear and corrugating stand  40 , a cut-off machine  42  slices desired lengths, constituting the individual floor members  10 . The shearing and corrugation stand  40  may be retrofitted into an existing roll forming machine such as, for example, roll forming machine Model No. M2½-24-9 which is available from the Bradbury Company Inc. of Moundridge, Kans. 67107. In this arrangement, the corrugation stand of the Model No. M2½-24-9 is replaced with the shearing and corrugation stand  40  of the present invention. 
     FIGS. 3 and 4 show the shearing and corrugation stand  40  in greater detail. The shearing and corrugation stand  40  includes a first roller  42 , a second roller  44 , a frame (not shown) for mounting the first and second rollers  42  and  44 , and a drive mechanism  49  for driving the first and second rollers  42  and  44 . 
     The first roller  42  includes a plurality of shear blades  54  which are shown in more detail in FIGS.  5   a - 5   c.  Each shear blade  54  is arranged transversely to the first roller  42  and parallel to each other around a periphery of the first roller  42 . The first roler  42  is adjustably mounted so that the depth to which the teeth of the first and second rollers mesh may be varied. In addition, each of the shear blades  54  is equally spaced around the periphery of the first roller  42 . This arrangement provides for a uniform formation of the ventilation slots  20  on the floor members  10 . 
     Referring specifically to FIGS.  5   a - 5   c , each of the plurality of shear blades  54  on the first roller  42  has a first side section  60 , a second side section  62 , and a top surface  63 . The first and second side sections  60  and  62  each have recesses  64  therein to form shearing edges or teeth  66 . The recesses  64  are U-shaped only because of the milling tool used to cut them, but can be of any suitable dimension and shape. The first side section  60  also has mounting holes  69  which are used to mount the shearing blade  54  in a radial groove on the first roller  42 . The shearing edges  66  of the first and second side sections  60  and  62  on the first roller  42  are alternately displaced with respect to each other so that a shearing edge  66  on one section is arranged opposite to a recess  64  on the other section. The illustrated embodiment depicts the first side section  60  with seven (7) cutting edges  66  and eight (8) recesses  64  and the second side section  62  with eight (8) cutting edges  66  and seven (7) recesses  64 . The top surface  63  of the shear blades  54  of the first roller  42  is flat. However, it is to be understood that the shape of the top surface  63  may be varied to suit particular design applications. 
     The second roller  44  also has a plurality of shear blades  70  which are shown in more detail in FIGS.  6   a - 6   c.  The shear blades  70  are arranged transversely to the second roller  44  and parallel to each other around a periphery of the second roller  44 . In the illustrated embodiment the second roller  44  is fixed in the roll forming machine  26  so that the height of the shearing blades  70  is fixed and so only the first roller  42  is movable with respect to the second roller  44 . Of course, this arrangement may be varied to suit the particular machine. The shear blades  54  and  70  of the first and second rollers  42  and  44  are arranged to mesh with each other to cut and open slots in sheet-metal strip  28  and at the same time provide the transverse corrugations in the strip  28 . 
     Each of the plurality of shear blades  70  of the second roller  44  has a first side section  72 , a second side section  74  and a top surface  76 . The first and second side sections  72  and  74  each have recesses  78  therein to form shearing edges or teeth  80 . The first side section  72  also has mounting holes  79  which are used to mount the shearing blade  70  in a radial groove on the first roller  44 . The shearing edges  80  of the first and second side sections  72  and  74  are alternately displaced with respect to each other so that a shearing edge  80  on one section is arranged opposite to a recess  78  on the other section. The top surface  76  of the first and second side sections  72  and  74  of the second roller  44  includes an upwardly extending beveled or crowned surface  82 . The beveled surface  82  rounds the peaks  22  of the floor member  10  to eliminate the sharp edges which usually form around the drilled or punched ventilation slots  20 . The first and second rollers  42  and  44  preferably have an outer diameter of 6 to 8 inches and a length of approximately 10 inches, however these dimensions may vary depending on the application. 
     The drive mechanism  49  includes a motor force  50  applied to one or both of the rollers  42  and  44 . In either case the first and second rollers have a gear arrangement  57  at the peripheral ends thereof to maintain the alignment and integrity of the first and second rollers  42  and  44  and the station  40 . A guide roller (not shown) is also well known and is used at the edges of the first and second rollers  42  and  44  to keep the sheet-metal strip  28  on track through the shearing and corrugation stand  40 . The guide roller may be provided to ride in the female support channel  14 . 
     The sheet-metal strip  28  which is still flat in its central portion advances through the shearing and corrugation stand  40  at a rate of between 30 to 100 feet/minute. As the sheet-metal strip  28  proceeds through the shearing and corrugation stand  40 , each tooth on the shearing blades  54  and  70  engages the sheet-metal strip  28  and cuts a slit. For a typical shearing action, it is desirable to maintain a clearance between the teeth of the shearing blades  54  and  70  of between 5% to 10% of the thickness of the strip  28  metal thickness as the teeth mesh together. As the teeth continue to mesh with each other, the slits are stretched open to form ventilation slots  20 . Further meshing of the teeth of the shear blades  54  and  70  provides the transverse corrugations peaks and valleys  22  and  24  on the sheet-metal strip  28 . 
     This single stage operation using the shearing teeth on the first and second roller  42  and  44  produces some stretching in the sheet-metal strip  28  which distorts the shape of the ventilation slots  20  on the floor members  10 . The tight meshing of the shearing blades  54  and  70  allows them to shear, open and corrugate the strip  28  as shown in FIG.  3 . By adjusting the depth that the shearing blades  54  and  70  enter each other, it is possible to control the height of the ventilation slots  20 . By changing the shape of the top surface  76  of the shearing blades  70 , it is also possible to adjust the height of the corrugations. This is desirable because smaller holes are necessary to keep smaller grains such as such rice from falling through the floor compared to larger openings which allow more air to flow for larger grains such as corn. 
     The ventilation slots  20  which are formed using the method and apparatus of the present invention have a more rectangular shape due to the dual shearing blades  54  and  70 , compared to the elliptical shape of the prior art techniques such as is disclosed in the Simmons U.S. Pat. No. 4,418,558. The rectangular ventilation slots  20  of the present invention allow more open space for better air flow therethrough. 
     The floor members  10  manufactured by the method and apparatus of the present invention are characteristically quite strong, relative to the thickness and strength of the sheet-metal employed in fabrication, due to the combination of the arch and corrugated construction employed for in central floor portions  12  of the floor members. Furthermore, since no sheet-metal has been cut from the central floor portion  12 , the substantial reduction in strength that occurs with punch perforation techniques is not encountered. At the same time, the cost of a perforating punch stand for the roll forming machine is eliminated, so that the method and apparatus of the invention result in a substantial economic benefit over the prior art punch perforation methods. Moreover, the shearing and corrugation stand  40  of the present invention accomplishes in one operation, the combined operation of the lancing stand and the corrugation stand described in the Simmons U.S. Pat. No. 4,418,558. The shearing and corrugation stand  40  of the present invention is more cost and space efficient than the prior techniques and provides a simpler and unique manufacturing technique over the state of the art. In addition, retrofitting of existing roll forming machinery now requires replacement of only one stand instead of two or more stands. 
     Although the present invention has been described with reference to preferred embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention.