Abstract:
A band saw includes a drive wheel and a fixed, curved band saw guide surface having one or more tracks for one or more band saw continuous strips. The one or more tracks contains lubricant openings which are accessed from a source of lubricant under pressure to reduce frictional resistance of the band saw moving over the guide surface.

Description:
This is a divisional application of National application Ser. No. 11/409,995 filed Apr. 25, 2006 now abandoned and currently pending. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to an improvement in a band saw apparatus and, particularly, a simplification of the apparatus including replacement of the conventional, upper idler wheel with a low friction guide surface. This arrangement will enhance the control of the tension in the band saw as well as reduce the expense in constructing and operating such machinery. 
     BACKGROUND OF THE INVENTION 
     In the lumber industry, a number of apparatuses have been employed to cut timber into usable pieces for subsequent operations or usage. Frequently, a wood cant must be cut into fairly thin but elongated pieces and typically band saws are used to accomplish this operation. In conventional band saws, such as represented by U.S. Pat. Nos. 4,061,066, issued Dec. 6, 1977, 6,745,644, issued Jun. 8, 2004, 5,557,989, issued Sep. 24, 1996 and 5,819,613, issued Oct. 13, 1998, an endless band saw is looped around an idler pulley wheel and a drive wheel which is motor driven and operated at high speed to rotate the drive wheel and, hence, the band saw over the pulley wheel while cants or wooden pieces are transported by a conveyor or manually against the cutting teeth of the band saw. Tension on the band saw is maintained by adjusting the distance between the central axis of rotation of the pulley and the drive wheel. The maintenance of the proper tension in the band saw loop is critical to efficient cutting operation and the avoidance of damage to the band saw loop. In particular, an improper low tension will result in wastage of the wood product since vibration of the loop will increase the size of the kerfs or cut made in the wood and can lead to breakage of the band itself. 
     SUMMARY OF THE INVENTION 
     In the present invention, the rotatable idler pulley is eliminated and replaced by a low friction curved guide member that has one or more guide tracks for individual band saw loops. The drive wheel, which is typically but not always located vertically below the surface, provided by the present invention may be formed with a corresponding number of tracks to enhance guidance of the band saw or saws. In addition, the drive wheel may be provided with sprocket teeth on the track surfaces to cooperate with sprocket openings formed along one edge of the band saw opposite the edge on which the cutting teeth are formed. Further, the guide track surface or each guide track surface of the curved guide member is formed with a number of lubricating openings connected to a source of lubricant under pressure or continuous grooves which will also be supplied with a lubricant under pressure. Air under pressure may also be provided with the lubricant so that the band saw moving over the guide track surface will encounter as little friction resistance as possible. 
     One advantage of the arrangement of the present invention is the simplification of a band saw apparatus since the guide track surface will require substantially less maintenance then the idler pulley currently in use. Also, typically the idler pulleys presently in use are relatively heavy as compared with the guide track surface used in the present invention. The weight saving may significantly extend the life of the drive motor for the drive pulley. Additionally, the use of a fixed guide track surface will allow the introduction of closely adjacent, multiple loop tracks which will be spaced apart at the cutting site by virtue of the different radii of each of the tracks as will become apparent from the following description. Further, the use of the stationary guide track surface will reduce vibrations in the band saw during use and thereby result in a reduced kerf size and will allow thinner cutting to be accomplished. 
     The foregoing and other advantages will become apparent as consideration is given to the follow detailed description taken in conjunction with the accompanying drawings, in which: 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic view in side elevation of the apparatus of the present invention; 
         FIG. 2  is a view along lines  2 - 2  of  FIG. 1 ; 
         FIG. 3  is a top plan view similar to  FIG. 1  of an alternative embodiment; 
         FIG. 4  is a side view in elevation of a further alternate embodiment of the invention; and 
         FIG. 5  is a side view is similar to that of  FIG. 4  but showing additional guide tracks; 
         FIGS. 6A and 6B  illustrate a schematic view of an improved band saw and a modified drive wheel, respectively, and; 
         FIG. 7  is sectional view of a multiple path band saw slide arrangement where the individual track surfaces are independently adjustable relative to a common drive pulley and to each other to vary the size of the cut lumber pieces 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to the drawings, wherein like numerals designate corresponding parts throughout the several views, there is shown schematically in  FIG. 1 , a band saw generally designated at  10  which includes an upper located guide member  12 , a vertical support arm  18  extending from a base  14  which houses a motor  20  shown in broken lines which drives which drives a drive wheel which is rotatably mounted on an axle carried by the base  14 . A conventional band saw  16  which is in the form of a continuous loop extends over the curved surface of the guide member  12  and around the drive wheel in a closed path, wherein the closed path includes a rectilinear section to allow access by a workpiece to the band saw&#39;s  16  cutting teeth  62 . To effect cutting, a workpiece, or piece of timber, will be fed against the cutting edge of the band saw  16 , at position  29 , on a conveyor (not shown) typically on one side of the drive wheel and guide member  12 . 
     As shown in the enlarged sectional view of  FIG. 2 , the guide member  12  is provided with a guide track  22  and, on one side of the guide track  22  there is provided a guide shoulder  25  to insure retention of the band saw  16  on the guide track surface and in a stable position relative to a plurality of lubricating openings or grooves formed in the guide track surface. A number of techniques are available for reducing friction and assuring smooth operation and passage of the band saw over the smoothly arcuate guide track surface. For example, in one form, the guide track surface may be provided with a plurality of grooves  23  spaced apart along the width of the guide track surface and extending along at least a portion of the path of travel of the band saw  16 . A lubricant may be fed under pressure through one or more tubes  24   a  to continuously lubricate the underside of the band saw  16 . Alternatively, the lubricant, such as a hydraulic fluid, may be mixed with air under pressure and pumped to the groove chambers  23  underlying the groove openings on the guide track surface. 
     An alternative structure is illustrated in the top plan view of  FIG. 3 , where in place of the elongated grooves, multiple rows of openings  26  may be provided to extend across the width of the guide track surface. Similar to the embodiment of  FIG. 2 , each of these openings  26  will be provided with access to a hydraulic fluid under pressure such as through tubes  24  which will be connected to a supply source  200  via a pump  31 , which may also supply pressurized air with the hydraulic fluid to the openings  26  to facilitate the transport of the band saw  16  over the guide track surface. The amount of pressure used for the fluid whether hydraulic, air or a combination of these, will, of course, depend on the weight of the bandsaw and the tension under which it is operating as will be apparent to those skilled in this technology. 
     With reference to a  FIGS. 4 and 5 , there are shown alternative forms of the present invention where the guide member  12 A is formed with a base  40  and a plurality of guide tracks  34  each of different radius relative to a center  32  and each will carry a separate band saw loop. Each guide track  34  is separated from an adjacent track by a wall member, one of which is indicated at  52 . As will be apparent from  FIG. 5 , a large number of guide tracks, such as at  42 - 50 , may be provided with decreasing radii from  42  to  50 . This will have the effect of spatially separating the band saws at the wood cutting site. The corresponding drive wheel, mounted on base  14 , need simply have the adequate axial width to accommodate the number of tracks for the number of band saws used. Also, each of the tracks  42 - 50  will be provided with either the grooves or openings in its surface described above in conjunction with  FIGS. 1-3  to receive the pressurized hydraulic fluid and/or air but these features some of which are indicated at  51  but are omitted from the other tracks for the sake of clarity. The guide track surface in these embodiments is preferably made from case hardened steel and must be fixed rigidly on the post  18  to minimize or eliminate vibration during operation of the apparatus. 
     Referring to  FIG. 6 , there is shown a segment of a band saw  60  having the usual cutting teeth  62  along one edge and on the opposite edge there are provided sprocket holes  64  for cooperating with sprocket teeth  66  formed on the surface of a drive wheel  14 B. With this arrangement in place, variations in tension in the band saws moving over the guide members  12  and  12 A will be minimized. 
     In  FIG. 7 , a further arrangement is shown where each band saw  70 ,  72 ,  74 ,  78  and  80  is provided with a separate support slide  82 ,  84 ,  86 ,  88 ,  90  and  100 . The slides  82 ,  84 ,  86 ,  88 ,  90  and  100  are substantially identical apart from the size of the mounting bases such as at  102  so that the following description will be understood to apply to each slide  82 ,  84 ,  86 ,  88 ,  90 , and  100 . 
     Slide  82  has an elongated arm  104  which has an upper slide surface  106  which is provided with a plurality of openings such as indicated at  108 . The openings  108  are spaced across the surface  106  to underlie the band saw  112 . The base member  102  is provided with a lubricant feed passage  110  which is supplied with a lubricant which may be mixed with air under pressure from a pump (not shown). The band saw  112  has its cutting edge extending beyond the end of arm  104  as shown at  114 . 
     A mechanism for spacing the slides  82 ,  84 ,  86 ,  88 ,  90 , and  100  may include a set of drive screws such as indicated at  118  each of which is connected to a gear system  111  rotatably carried in each base member  102  to permit selective rotation of the gears and activation of corresponding drive screws to change the spacing between the arms. Separate electric motors (not shown) may be used to control selected ones of the gears of the system to effect independent movement of the slides toward or away from each other. This can be accomplished by control circuitry of a conventional type to allow selective actuation of selected gears  113  of the system. 
     Having described the invention, it will be apparent to those skilled in this art that various modifications may be made therein without departing from the spirit and scope of this invention as defined in the accompanying claims.