Abstract:
Described is an adjustable roll drive including a fixed drive cylinder having a fixed drive gear, a fixed intermediate gear rotated by the fixed drive gear, a movable intermediate gear rotated by the fixed intermediate gear, and a movable driven cylinder having a movable driven gear wherein the movable driven gear is rotated by the movable intermediate gear. A linkage system is employed to maintain a substantially constant distance between axes of successive gears and an adjustment mechanism to vary a distance between the fixed drive cylinder and the movable driven cylinder. The continuously adjustable roll drive may be adapted further for use in grain grinding operations.

Description:
FIELD OF INVENTION  
       [0001]     This invention generally relates to an improved mill roll drive that is capable of adjustment during use and without the necessity for change gears.  
       BACKGROUND INFORMATION  
       [0002]     To produce flour, grain may be fed between two elongated grinding cylinders separated by a specified distance or gap. The milling process may consist of different grinding stages depending on the desired grind of the final product. During the milling process, the grinding cylinders are subject to wear and must be adjusted to maintain the desired gap. A first grinding cylinder axis may be fixed in position while a second grinding cylinder axis is adjustable.  
         [0003]     Conventional flour mill roll stands are equipped with oil lubricated gear boxes and utilize change gears to maintain the gap when grinding cylinders wear. A grinding cylinder drive gear may be repeatedly changed for a smaller drive gear to reduce the distance between the grind cylinder axes and thus reduce the gap between the grinding cylinders. In general, millers may change the drive gear up to eight times before replacing a grinding cylinder. Fine adjustments are achieved before replacing a drive gear by moving the adjustable axis of the first grinding cylinder closer to the fixed axis of the second grinding cylinder. The respective drive gears of the first and second grinding cylinders are also moved closer together as a result. Consequently, the drive gears are running outside of the optimal pitch line approximately 90% of the time, thus causing premature gear wear. Regular adjustment to gear position also results in gear box seal leaks.  
         [0004]     To overcome the problems associated with gear driven roll drives, belt drives and chain drives have been employed. The use of change gears may be avoided, but belts are subject to high tension and may break without warning requiring emergency repair. Belts must also be tensioned after each adjustment requiring the mill to stand still. Chains experience similar problems as belts and additionally must be lubricated.  
       SUMMARY OF THE INVENTION  
       [0005]     The present invention is directed to a continuously adjustable roll drive. The roll drive according to the present invention may be adjusted without the use of change gears or running the gears outside of the pitch line. The roll drive according to the present invention comprises a fixed drive cylinder having a fixed drive gear, a fixed intermediate gear rotated by the fixed drive gear, a movable intermediate gear rotated by the fixed intermediate gear, and a movable driven cylinder having a movable driven gear, wherein the movable driven gear is rotated by the movable intermediate gear. The roll drive further comprises a linkage system to maintain a substantially constant distance between axes of successive gears, and an adjustment mechanism to vary a distance between the fixed drive cylinder and the movable driven cylinder.  
         [0006]     One embodiment of the present invention further comprises grinding cylinders for use in the grain grinding operations of flour mills and/or breweries. In an additional exemplary embodiment, at least one of the gears of the continuously adjustable roll drive is a self-lubricating non-metal gear.  
         [0007]     The present invention is also directed to a method of adjusting a distance between two rotating cylinders, comprising the steps of maintaining a substantially fixed pitch line between a fixed drive gear and a fixed intermediate gear, wherein the fixed intermediate gear transfers motion of the drive gear; maintaining a substantially fixed pitch line between the fixed intermediate gear and a movable intermediate gear, wherein the movable intermediate gear transfers motion of the fixed intermediate gear; maintaining a substantially fixed pitch line between the movable intermediate gear and a movable driven gear, wherein the movable driven gear transfers motion of the movable intermediate gear and the movable driven gear is a first distance from the fixed drive gear; and actuating an adjustment mechanism to move the movable driven gear to a second distance from the fixed drive gear, wherein the substantially fixed pitch lines are maintained during the movement. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0008]     The accompanying drawings are included to provide a further understanding of the invention and are incorporated in and constitute part of the specification, illustrate several embodiments of the invention and, together with the description, serve to explain examples of the present invention. In the drawings:  
         [0009]      FIG. 1  shows an isometric view of an exemplary embodiment of the roll drive according to the present invention including two grinding cylinders;  
         [0010]      FIG. 2  shows a first side view of an exemplary embodiment of the present invention;  
         [0011]      FIG. 3  shows a second side view of an exemplary embodiment of the present invention;  
         [0012]      FIG. 4  shows a third side view of an exemplary embodiment of the present invention;  
         [0013]      FIG. 5  shows a cross-sectional view of a rotation mechanism according to the present invention;  
         [0014]      FIG. 6  shows a fourth side view of an exemplary embodiment of the present invention;  
         [0015]      FIG. 7  shows a cross-sectional view of plane A-A as represented on  FIG. 6 ;  
         [0016]      FIG. 8  shows a cross-sectional view of plane B-B as represented on  FIG. 6 ; and  
         [0017]      FIG. 9  shows a cross-sectional view of plane C-C as represented on  FIG. 6 .  
     
    
     DETAILED DESCRIPTION  
       [0018]     The present invention is directed to a continuously adjustable roll drive. The roll drive according to the present invention may be useful as a flour mill roll drive. However, those of skill in the art will understand that there are other applications to which the present invention may be directed. It should be noted that all the gears of the exemplary embodiment described herein may be non-lubricated gears because of the novel arrangement presented herein. Thus, the present invention eliminates the need for any lubrication of the gear mechanism.  
         [0019]      FIG. 1  shows an exemplary embodiment of the roll drive  1 . The roll drive  1  may be supported by a roll drive stand  2  or other support means known to those of ordinary skill in the art. The roll drive  1  comprises a drive gear  4  and a driven gear  6 . The drive gear  4  and the driven gear  6  are free to rotate about separate and substantially parallel longitudinal axes  8  and  10 , respectively. The longitudinal axis  8  of the drive gear  4  is in a fixed position with reference to the roll drive  1 . In an exemplary embodiment of the present invention shown in  FIGS. 5-8 , the distance between the fixed longitudinal axis  8  of the drive gear  4  and a movable longitudinal axis  10  of the driven gear  6  is approximately 0.26 m (10.06 in). Those skilled in the art will understand that the dimensions provided throughout this description are only exemplary dimensions for the described exemplary embodiment. Other embodiments may include dimensions different from those described herein.  
         [0020]     As shown in  FIG. 1 , the roll drive  1  includes at least two intermediate gears comprising a first intermediate gear  12  and a second intermediate gear  14 . The first intermediate gear  12  and the second intermediate gear  14  are free to rotate about separate and substantially parallel axes, a fixed axis  16  of the first intermediate gear  14  and a movable axis  18  of the second intermediate gear  14 . The fixed axis  16  of the first intermediate gear  12  is fixed in position with reference to the roll drive  1 , either by connection to the roll drive stand  2  or other means known to those of ordinary skill in the art. The first intermediate gear  12  is in communication with the drive gear  4  and the second intermediate gear  14 .  
         [0021]     In an exemplary embodiment shown in  FIGS. 5-8 , the relative distance between the fixed longitudinal axis  8  of the drive gear  4  and the fixed axis  16  of the first intermediate gear  6  is approximately 0.21 m (8.21 in.). The second intermediate gear  14  is in communication with the driven gear  6  thereby allowing the drive gear  4  to indirectly rotate the driven gear  6  via the first intermediate gear  12  and the second intermediate gear  14 . A means of supplying continuous torque may be included in communication with the drive gear  4 .  
         [0022]     Shown in  FIG. 1 , the roll drive  1  may comprise a linkage system to fix and maintain the relative distances between the axes of any or all of the gears and desired pitches between the respective gears. Such linkage system may comprise a first linkage  20  with a first end  22  and a second end  24 , and a second linkage  26  with a first end  28  and a second end  30 . The first end  22  of the first linkage  20  is connected to the second intermediate gear  14  and the second end  24  is connected to the driven gear  6 . The first end  28  of the second linkage  26  is connected to the first intermediate gear  12  and the second end  30  is connected to the second intermediate gear  14 . The drive gear  4  and the first intermediate gear  12  may optionally be connected via a third linkage  32 . However, since drive gear  4  and intermediate gear  12  may be fixed to a frame (not shown) of the roll drive  1 , the third linkage may not be required. In an exemplary embodiment of the present invention shown in  FIGS. 5-8 , the distance between the fixed axis  16  of the fist intermediate gear  12  and the movable axis  18  of the second intermediate gear  14  is approximately 0.22 m (8.69 in), and the distance between the movable axis  18  of the second intermediate gear  14  and the movable longitudinal axis  10  of the driven gear  6  is approximately 0.23 m (9.18 in).  
         [0023]     The roll drive  1  may also comprise a first grinding cylinder  34  and a second grinding cylinder  36 . The first grinding cylinder  34  and the second grinding cylinder  36  are preferably of an elongated cylinder shape. The first grinding cylinder  34  and the second grinding cylinder  36  are attached to the drive gear  4  and the driven gear  6 , respectively, and are free to rotate about longitudinal axes  8  and  10  respectively. In an exemplary embodiment of the present invention shown in  FIGS. 5-8 , the first grinding cylinder  34  and the second grinding  36  cylinder are approximately 0.25 m (10 in) in diameter and 1.02 m (40 in) in length.  
         [0024]     The roll drive  1  also includes an adjustment means for varying the relative distance between the driven gear  6  and the drive gear  4 , and consequently varying the relative distance between the second grinding cylinder  36  and the first grinding cylinder  34  if employed.  FIG. 2  shows a first side view of the gearing mechanism for the roll drive  1 . As shown in  FIG. 2 , the adjustment means may comprise an adjustment lever  38 . The adjustment lever  38  may include a first end  40  and a second end  42 . The first end  40  may be coupled at location  41  to a frame (not shown) of the roll drive  1  and free to rotate about an axis fixed in relation to the roll drive  1 . As would be understood by one skilled in the art, the cylinder  36  includes a shaft (not shown) which is coupled to the drive gear  6  to cause the cylinder to rotate. The adjustment lever  38  may be rotationally coupled to the driven gear  6  and cylinder  36  combination by the shaft (not shown) being inserted through a via in the adjustment lever  38 . The adjustment lever  38  may be mounted in this manner on either side of the driven gear  6 , i.e. the side closest to the cylinder  36  or the side away from the cylinder  36 . In addition, those skilled in the art will understand that other manners of coupling the adjustment lever  38  to the driven gear  6  may be used as long as the driven gear  6  is free to rotate about the longitudinal axis  10 .  
         [0025]     In the exemplary embodiment, the adjustment lever  38  includes a curved shape allowing the adjustment lever  38  to curve around the circumference of the driven gear  6  and/or the cylinder  36  and extend to the front of the mill stand where it is accessible. The adjustment lever  38  may take on other shapes as long as it does not interfere with the rotation of any of the gears  4 ,  6 ,  12 , or  14  or the cylinders  34  and  36 . The second end  42  may further be connected to an adjustment control  44  comprising, for example, a screw and spring loaded mechanism for mechanical adjustment. In other embodiments, the adjustment control  44  includes an automated adjustment device.  
         [0026]     As shown in  FIG. 2 , the adjustment lever  38  may be coupled to the driven gear  6  as described above. The adjustment lever  38  may be capable of movement in a direction  46  and a direction  48  via the adjustment control  44 . In an exemplary embodiment according to the present invention, displacement of the second end  42  of the adjustment lever  38  may result in a change in the position of the driven gear  6 .  
         [0027]      FIG. 3  shows a second side view of an exemplary embodiment of the gearing mechanism for the roll drive  1 . The second end  42  of the adjustment lever  38  may be displaced in the direction  46 . As a result, the driven gear  6  may move closer to the drive gear  4  and the distance between the longitudinal axes  8  and  10  may decrease. The driven gear  14  may also be displaced to remain in contact with the driven gear  6 .  
         [0028]      FIG. 4  shows a third side view of an exemplary embodiment of the gearing mechanism for the roll drive  1 . The second end  42  of the adjustment lever  38  may be displaced in the direction  48 . As a result, the driven gear  6  may move in a direction away from the drive gear  4 . The distance between the longitudinal axes  8  and  10  may increase and the driven gear  14  may also be displaced.  
         [0029]     As  FIGS. 3 and 4  show, the position of the driven gear  6  relative to the drive gear  4  may be adjusted using the adjustment lever  38  while maintaining uninterrupted communication between the drive gear  4  and the first intermediate gear  12 , the first intermediate gear  12  and the second intermediate gear  14 , and the second intermediate gear  14  and the driven gear  6 . Therefore, the distance between the driven gear  6  and the drive gear  4 , or a gap between the first grinding cylinder  34  and the second grinding cylinder  36 , may be adjusted while supplying a continuous torque to the gearing mechanism.  
         [0030]     In an exemplary embodiment according to the present invention, the adjustment lever  38  may be used for coarse adjustment of the position of the driven gear  6 . Fine adjustment of the position of the driven gear  6  may be accomplished with a handwheel (not shown) on the adjustment control  44 . As one of ordinary skill in the art will understand, the handwheel may rotate a screw (e.g., fixed to the second end  42  of the adjustment lever  38 ) to allow for fine adjustment in the directions  46  and  48  via, for example, counter-clockwise and clockwise rotation of the handwheel, respectively. In other embodiments, the adjustment control  44  includes an automated device. For example, an automated adjustment control  44  may be configured to continuously maintain a specified distance between the driven gear  6  and drive gear  8 .  
         [0031]     As one of ordinary skill in the art will understand, movement of the adjustment lever  38  during continuous milling operations will result in the movement of driven gear  6 , second intermediate gear  14  and linkages  20  and  26 . For example, the mill may be operating at full capacity meaning that each of the drive gear  4 , the first intermediate gear  12 , the second intermediate gear  14  and the driven gear  6  may be rotating at a high speed about their respective axes. An adjustment made to move the driven gear  6  closer to the drive gear  4  will cause the longitudinal axis  10  of driven gear  6  to be moved relative to each of the other gears  4 ,  12  and  14 . However, this adjustment will also result in movement of the second intermediate gear  14  relative to the driven gear  6  and the first intermediate gear  12 , i.e., the longitudinal axis  18  is moved relative to longitudinal axes  10  and  16 . This relative movement of the gears  6  and  14  is accomplished by a rotation of the first linkage  20  about the axis  18  (second intermediate gear  14 ) and the axis  10  (driven gear  6 ) and/or a rotation of the second linkage  26  about the axis  18  (second intermediate gear  14 ) and the axis  16  (first intermediate gear  12 ) The rotation of the linkages  20 / 26  about the respective axes may be considerably slower (and possibly opposite in direction) than the rotation of the gears about their respective axes. Therefore, a rotation mechanism may be used for each of the gears (e.g., the first intermediate gear  12 , the second intermediate gear  14  and the driven gear  6 ) which have multiple rotations about their axes (e.g., mill rotation and linkage rotation).  
         [0032]      FIG. 5  shows a cross-sectional view of an exemplary embodiment of a rotation mechanism  60  that is described with reference to the second intermediate gear  14 . However, the rotation mechanism may be included with any of the gears. The rotation mechanism  60  may include an inner bearing system  62  and an outer bearing system  64 . Each bearing system  62 / 64  may include at least one cylindrical bearing (e.g., ball bearings, roller bearings, etc.). The rotation mechanism  60  may also include an inner shaft  66  and an outer shaft  68 , each rotatable about the axis  18 . In the exemplary embodiment, the second linkage  26  is attached about the inner shaft  66 . The first linkage  20  is attached about the outer shaft  68 . The outer shaft  68  is rotatable about the inner shaft  66  via the inner bearing  62 . The second intermediate gear  14  is rotatable about the outer shaft  68  via the outer bearing system  64 . Thus, during the adjustment that was described above, the gear  14  may be rotating about axis  18  at the high rate of speed. However, the outer shaft  68  (and consequently the second linkage  26 ) and the inner shaft  66  (and consequently the first linkage  20 ) may be rotated at a much slower speed (or in an opposite direction) about axis  18  to compensate for the adjustment of moving the driven gear  6  closer to the driver gear  4 . In other embodiments (e.g., for first intermediate gear  12  and driven gear  6 ), the rotation mechanism may include only a single complex bearing facilitating the rotation of the gear and a single one of the linkages about the respective axis.  
         [0033]      FIG. 6  shows a fourth side view of an additional exemplary embodiment of the roll drive  1 . A plane A-A, a plane B-B, and a plane C-C are shown.  FIG. 7, 8 , and  9  show cross-sectional views of such exemplary embodiment corresponding to the plane A-A, the plane B-B, and the plane C-C respectively. Approximate dimensions of this exemplary embodiment are provided in inches.  
         [0034]     In an exemplary embodiment of the present invention, any or all of the gears employed are of a self lubricating non-metal type. Examples of such a self-lubricating gear system include those disclosed in U.S. Pat. No. 5,423,232, herein incorporated by reference. The term self-lubricating is used here to mean that no lubrication is necessary. This may be achieved, for example, but minimizing metal-to-metal contact in a gear system. For example, the drive gear  4  may be a self-lubricating non-metal gear and the first intermediate gear  12  may be a metal gear. Additionally, the second intermediate gear  14  may be a self-lubricating non-metal gear, and the driven gear  6  may be a self-lubricating non-metal gear or a metal gear. A non-metal material may comprise, but is not limited to, nylon  12 , lauramid, nyaltron, delrin, phenolic composites or combinations thereof. As would be understood by one of ordinary skill in the art, any or all of the gears may be secured to their respective axes using keyless locking devices.  
         [0035]     The roll drive  1  according to the present invention may be employed in milling operations to allow for the maintenance of a specified gap between the first grinding cylinder  34  and the second grinding cylinder  36 . The present invention allows for adjustments to be made at any time, even during milling operations, without replacing drive gears. Upon wear of either grinding cylinder, the adjustment lever  38  or other similar means may be manipulated to decrease the relative distance between the driven gear  6  and the drive gear  4 , thus reducing the gap between the grinding cylinders. Therefore, the present invention eliminates the need for change gears.  
         [0036]     The roll drive  1  according to the present invention allows for the gear mechanism to rotate freely without tension between gears. Coarse or fine adjustments may be made using the exemplary embodiments of the present invention and these adjustments will have no affect on the pitch line of the gears, i.e., the gears remain in pitch line mesh through the entire adjustment range. Therefore, the present invention allows for a desired tooth mesh to be maintained at all times facilitating optimal gear life.  
         [0037]     It will be apparent to those skilled in the art that various modifications and variations can be made in the structure and the methodology of the present invention, without departing from the spirit or scope of the invention. Thus, it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.