Abstract:
A method and apparatus for determining a pinion bearing move to correct pinion-to-gear alignment based on pinion Δ t overcoming the aforementioned drawbacks are provided. Using a realistic visual representation of a gear to pinion mesh showing pressure angles of the gear and pinion as well as the angle of the pinion down from the mill center line allows for a quick and accurate determination of a pinion bearing to align a pinion-to-gear assembly move. Using temperature differential data of the pinion under load conditions, the present invention allows for an easy and efficient means of determining a pinion bearing move to align a pinion-to-gear assembly without requiring complicated manual calculations or data input to a computer program. Furthermore, the present invention is lightweight and portable thereby avoiding the drawbacks often associated with handheld electrical devices and laptop computers.

Description:
BACKGROUND OF INVENTION  
         [0001]    The present invention relates generally to pinion-to-gear alignment and, more particularly to, a method and apparatus for determining a pinion bearing move to achieve proper pinion-to-gear alignment based on temperature differentials of a pinion and a visual representation of a pinion-gear assembly.  
           [0002]    Pinion-gear assemblies are widely used in a number of industrial and commercial systems, such as grinding mills. Conventional grinding mills are typically driven by a ring gear attached to the body of the mill. An electric motor or, in some circumstances, a gasoline powered engine, drives a pinion which powers the ring gear. To minimize wear and tear on the gear and pinion as well as to prevent costly down time due to broken or damaged teeth on the gear or pinion, it is imperative that the pinion be properly aligned to the ring gear. A number of techniques have been developed to properly align the pinion to the ring gear.  
           [0003]    In one known method, an initial alignment of the pinion to the gear is achieved by collecting mechanical readings with feeler gauges and then making the best alignment possible based on those readings. Typically, this initial alignment is made with the pinion in a static condition and having no loads. As is well known, the pinion will take a slightly different position when running and under load conditions. Additionally, the alignment (or load distribution) of the pinion to the gear teeth will generate temperatures that are proportional to the load distribution. Simply, the side of the pinion with the heaviest load distribution will have higher temperatures than the side of the pinion with the lightest load distribution. These temperature differentials of the pinion when running with a load may be used to perform an alignment of the pinion-to-gear to achieve an even load distribution across the pinion teeth.  
           [0004]    Complicating matters however, is that grinding mills are often driven by more than one pinion. Further, in grinding mills it is not uncommon for each pinion to be running in two directions. For example, autogenuous and semi-autogenuous mills are typically run in alternating directions in order to achieve longer liner life. Under these conditions, temperature data must be recorded on both pinions and in both directions. Additionally, a gear pressure angle, an angle of each pinion down from the mill center line, and a rotation of the mill while taking the temperature readings must be known in order to calculate a proper pinion move for realignment thereof. A number of computer programs have been developed to calculate pinion realignments based on temperature data. These specific programs are particularly well suited when the proper data is input directly into the program. However, it is relatively easy to make a mistake in the input of data into the computer program which ultimately could result in a damaged or broken gear or pinion due to an ill-advised alignment move. Additionally, manual calculations may be used to calculate a pinion realignment move, but manual calculations require considerable time and an extensive working knowledge of geometry as well as trigonometry.  
           [0005]    It would therefore be desirable to design an apparatus and method for determining a pinion bearing move to align a pinion-to-gear assembly quickly and less prone to error without requiring a computer program or a number of complex manual calculations.  
         BRIEF DESCRIPTION OF INVENTION  
         [0006]    A method and apparatus for determining a pinion bearing move to align a pinion-to-gear assembly overcoming the aforementioned drawbacks are provided. Using a realistic visual representation of a gear to pinion mesh showing pressure angles of the gear and pinion as well as the angle of the pinion down from the mill center line allows for a quick and accurate determination of a pinion bearing move to align the pinion-to-gear. Using temperature differential data of the pinion under load conditions, the present invention allows for an easy and efficient means of determining a pinion bearing move to align the pinion-to-gear without requiring complicated manual calculations or data input to a computer program. Furthermore, the present invention is lightweight and portable thereby avoiding the drawbacks often associated with handheld electrical devices and laptop computers.  
           [0007]    Therefore, in accordance with an aspect of the present invention, a method for determining a pinion bearing move for a pinion-to-gear alignment assembly comprises positioning a gear tooth to a first angle and positioning a pinion tooth to a starting position. The method further includes determining a pinion temperature differential, Δt, and repositioning the pinion tooth to a corrected position based on the pinion temperature differential. The method further includes determining a distance from the starting position to the corrected position.  
           [0008]    In accordance with another aspect of the present invention, a nomograph includes a gear tooth having a number of temperature gradient reference marks. The nomograph further includes a pinion tooth having a pair of aligned reference lines. The nomograph further includes a gradient grid having a plurality of reference points for determining a pinion bearing adjustment move.  
           [0009]    In accordance with yet another aspect of the present invention, a tool for realigning a pinion to gear assembly is provided. The tool includes a visual representation of a gear to pinion mesh illustrating pressure angles of a gear and pinion assembly. The tool further includes an instructional manual having a set of instructions for determining one or more pinion bearing moves based on one or more pinion temperatures.  
           [0010]    Various other features, objects, and advantages of the present invention will be made apparent from the following detailed description and the drawings. 
       
    
    
     BRIEF DESCRIPTION OF DRAWINGS  
       [0011]    The drawings illustrate one preferred embodiment presently contemplated for carrying out the invention.  
         [0012]    In the drawings:  
         [0013]    [0013]FIG. 1 is a top view of a nomograph in accordance with the present invention.  
         [0014]    [0014]FIG. 2 is an exploded view of the nomograph of FIG. 1.  
         [0015]    [0015]FIG. 3 is a cross-sectional view of the nomograph of FIG. 1.  
         [0016]    [0016]FIG. 4 is a top view of a portion of the nomograph of FIG. 1 showing a pinion tooth at a starting position.  
         [0017]    [0017]FIG. 5 is an enlarged view of a portion of the nomograph shown in FIG. 4.  
         [0018]    [0018]FIG. 6 is a top view of a portion of the nomograph of FIG. 1 showing movement of a pinion tooth to a corrected position in accordance with the present invention.  
         [0019]    [0019]FIG. 7 is an enlarged view of a portion of the nomograph shown in FIG. 6 illustrating movement of the pinion tooth from a starting position to a corrected position in accordance with the present invention.  
         [0020]    [0020]FIG. 8 is a top view of a portion of the nomograph shown in FIG. 1 illustrating annular movement of a gear tooth and a pinion tooth in accordance with the present invention. 
     
    
     DETAILED DESCRIPTION  
       [0021]    Referring to FIGS.  1 - 2 , a nomograph  10  for determining a pinion bearing move to align a pinion-to-gear assembly based on temperature differentials of a pinion-gear assembly is shown. Nomograph  10  includes a gear tooth  12  and a pinion tooth  14 . In a preferred embodiment, pinion tooth  14  has a polygonal shape and a reference eyelet  15 , and is configured to be slidably positioned in pocket  16  of gear tooth  12 . Gear tooth  12  has a top surface  18  and an extending bottom surface  20  that cooperatively form pocket  16 . Movement of the pinion tooth  14  into pocket  16  is limited by a pair of convergent interfaces  22  joining the outer surface  18  to bottom surface  20 . That is, movement of pinion tooth  14  is prevented by the abutment of pinion tooth sidewalls  24  against interfaces  22 . Gear tooth  12  further includes a number of gradient reference lines  26  as well as a number of root change reference lines  28 . Two sets gradient reference lines  26  converge to an intersection (not shown) resulting in a mirrored alignment of the two sets.  
         [0022]    Additionally, each set of gradient reference lines includes a starting reference line  30  that is centrally disposed between the remaining reference lines  26 . Furthermore, reference line  30 , in a preferred embodiment, is conspicuously identified using a bold type.  
         [0023]    Gear tooth  12  further includes a linearly extending positioning line  32  that extends along a bottom surface  20 . Line  32  extends from an eyelet  34  laterally through the intersection of the sets of reference lines  26  and is hiddenly positioned underneath the number of vertically oriented linearly arranged root reference lines  28 . Reference line  32  then extends from underneath the number of root reference lines  28  laterally along surface  20 . After a momentary break, line  32  begins again along surface  20  and extends to an outer edge  36  of gear tooth  12 . Gear tooth  12  further includes an alignment point  38  centrally disposed along one of the root reference lines  28 .  
         [0024]    Nomograph  10  further includes an opaque base portion  40  having along the surface thereof a plurality of reference angle marks  42  angularly positioned from one another at, in a preferred embodiment, 5° intervals. A curvilinear grid  44  is also positioned along a top surface of base portion  40  and includes a plurality of angularly aligned reference points  46 . Reference points  46  are linearly aligned with angle reference marks  42 . Base portion  40  further includes a plurality of angular reference lines  48  extending angularly towards and in corresponding alignment with reference marks  42  from eyelet  50 . Base portion  40  may alternatively include a company name and logo section  52 .  
         [0025]    Nomograph  10  further includes a transparent sheath portion  54  having a plurality of curvilinearly aligned access windows  56 . As will be discussed shortly, reference windows  56  enable a user to slidably position pinion tooth  14  within pocket  16  of the gear tooth  12 . Sheath  54  further includes an eyelet  56  that is aligned with eyelet  34  of gear tooth  12  and the eyelet  50  of the base portion  40 . Sheath  54 , gear tooth  12 , and base portion  40  are fasteningly connected to one another by a peg  58 , FIG. 2, disposed through eyelets  56 ,  34 , and  50 . An angular ring or clamp  60 , FIG. 2, is used to secure components  12 ,  40 , and  54  of nomograph  10  to one another.  
         [0026]    Referring to FIG. 3, a cross-sectional view of nomograph  10  is shown illustrating the layered construction of sheath  54 , gear tooth top surface  18 , pinion tooth  14 , gear tooth bottom surface  20 , and base portion  40 . As shown, surface  20  of gear tooth  12  rests above base portion  40  but below pinion tooth  14 . Further, as is readily shown, sheath  54  is positioned atop the gear tooth surface  18  and pinion tooth  14 .  
         [0027]    Referring to FIG. 4, the gear tooth  12  and the pinion tooth  14  are shown positioned in one of a number of starting positions. That is, the gear tooth  12  is positioned such that reference line  32  is linearly aligned with the angle reference mark  42  corresponding to 15° . Further, pinion tooth  14  is positioned within pocket  16  such that gear tooth sidewalls  24  align with bolded gradient reference lines  30 . Further, pinion tooth leading edge  24 ( a ) is positioned to align with root reference line  28 ( a ). As a result of aligning the pinion tooth sides  24  and edge  24 ( a ) with reference lines  30 ,  28 ( a ), the pinion tooth eyelet  15  is aligned over a grid reference point  46  and, in the position illustrated in FIG.  4 , the pinion tooth eyelet  15  would be positioned over grid reference point  46 ( a ) which corresponds to angle reference mark 15° .  
         [0028]    Angle reference lines  42  correspond to an angle below mill center line. Therefore, positioning the gear tooth reference line  32  as shown in FIG. 4 corresponds to a 15° angle below mill center line. That is, the present invention is designed such that gear tooth  12  may pivot angularly from eyelet  56  such that a number of mill center line angles may be selected. While FIG. 4 sets forth angles ranging from 0 to 30° at 2½° intervals, this is shown for illustrative purposes only and is not meant to limit the scope nor the breadth of the instant invention. Further, the present invention is designed such that gear tooth  12  may be repositioned along any angular line while the pinion tooth  14  is slightably engaged within pocket  16 . Angular movement of the gear tooth-pinion tooth assembly  12 ,  14  may be achieved by simply moving gear tooth  12  and pinion tooth  14  through access windows  56  of sheath  54 , FIG. 2.  
         [0029]    [0029]FIG. 5 shows an enlarged view of the starting position achieved by placement of pinion tooth  14  within pocket  16  of gear tooth  12 . As may be readily seen, pinion tooth eyelet  15  is positioned such that grid point  46 ( a ) of gradient grid  44  is centrally positioned within the eyelet  15 . As indicated previously, this positioning of the gear tooth and pinion tooth is achieved when the gear tooth  12  is positioned to reflect a 15 below mill center line location of the pinion bearing assembly.  
         [0030]    Now referring to FIG. 6, the gear tooth-pinion tooth assembly  12 ,  14  is shown such that the position of the pinion tooth  14  within the pocket  16  and the gear tooth  12  have been moved to a corrected position  46 ( b ). Determining the proper pinion move to achieve corrected position  46 ( b ) is based upon pinion temperatures recorded of the pinion gear assembly. In one preferred embodiment, the pinion temperatures are recorded using an infrared heat gun whereupon temperatures are determined over a number of time intervals. These temperature readings are used to determine a temperature differential, Δt. For a dual direction mill, temperatures are recorded for both into mesh and out of mesh directions. The determined temperature differential of the pinion is then used to determine a scale for the pinion temperature change per gradient. For example, if the pinion temperature differential is greater than 30° F. and less than or equal to 60° F., then each gradient line  26  of the gear tooth  14  represents a 10° F. interval. If the pinion temperature differential is greater than 15° F. and less than or equal to 30° F., then each gradient reference line  26  represents a 5° F. interval. If the pinion temperature differential is less than 15° F., each gradient reference line  26  represents a 2½° F. interval. Furthermore, if the pinion tooth is moved laterally toward the gradient grid  44 , an “out of mesh” pinion move is being represented. However, if the pinion tooth is moved laterally away from the gradient grid  44 , an “into mesh” pinion move is being represented. If the pinion teeth on the top half of the pinion diverge with the gear teeth, this is considered to be “out of mesh” rotation. Conversely, if the pinion teeth on the top half of the pinion converge with the gear teeth, this is considered to be “into mesh” rotation.  
         [0031]    Now referring to FIG. 7, an enlarged view of the corrected position  46 ( b ) illustrated in FIG. 6 is shown. As readily shown in FIG. 7, the pinion tooth  14  has been moved “out of mesh” by two gradient lines as indicative by pinion tooth sidewalls  24  being moved inward of gradient reference line  30  by two gradient lines  26 . This “out of mesh” movement of the pinion tooth  14  results in pinion tooth opening highlighting a new gradient grid point or corrected position  46 ( b ).  
         [0032]    Once the pinion tooth  14  has been repositioned according to the proper temperature differential scale, it is possible to determine an appropriate pinion bearing move to correct for the measured temperature differential. That is, referring to the individual gradients of gradient grid  44  and by determining a position of the corrected position  46 ( b ) compared to the starting position  46 ( a ) and by measuring and determining the number of gradients along an x and y axis from the starting reference position  46 ( a ) to the corrected position  46 ( b ), it is possible to determine the appropriate pinion bearing move to correct the pinion alignment to the gear of a grinding mill. For example, the corrected position  46 ( b ) corresponds to approximately 3½ gradients along an x axis and one gradient downward along a y axis to the corrected position  46 ( b ). Therefore, to correct for the recorded temperature differentials, it is necessary to move the pinion out of the mesh 3½ gradients and downward one gradient.  
         [0033]    Determining the value of each gradient depends upon which temperature differential scale was used to determine pinion tooth repositioning. That is, in one embodiment, each gradient represents 0.5 thousandths of an inch if the pinion tooth was repositioned according to a 2½° F. gradient scale. Additionally and as best shown in FIG. 6, repositioning of the pinion tooth  14  causes a repositioning of pinion tooth leading edge  24 ( a ). The number of root gradient lines between initial position  38  and the position following movement of the pinion tooth is indicative of the relative root change of the pinion gear assembly that will result once the pinion gear assembly is recalibrated to correct the temperature differentials. Like each gradient of grid  44 , each root change line  28  has a different value depending upon which temperature differential scale was used in moving the pinion tooth. For example, if each gradient reference line  36  represents a 2½° F. per gradient change, then each root line  28  represents 0.25 thousandths of an inch of change. The table below sets forth the additional root change and pinion bearing per gradient values for each temperature differential scale.  
                                                 PINION TEMPERATURE CHANGE/GRADIENT                CHANGE IN                   PINION TEMP   PINION BEARING   RELATIVE       SCALE   PER GRADIENT   MOVE   ROOT CHANGE       NO.   (*)   (*)   (*)               1    2.5° F./GRAD.   .0005″/GRAD.     .00025/GRAD       2    5.0° F./GRAD   001″/GRAD.   .0005″/GRAD       3   10.0° F./GRAD.   002″/GRAD.    .001″/GRAD.                          
 
         [0034]    By determining the appropriate values, it is possible for a service technician, engineer, etc. to determine the appropriate pinion move.  
         [0035]    As indicated previously and referring to FIG. 8, the present invention is designed such that gear tooth  12  and pinion tooth  14  may be aligned at any number of angles depending upon the angle of the pinion bearing below mill center line. The gear tooth  12  and the pinion tooth  14  are positioned at a starting reference point  46 ( a ) and at a 30° angle below mill center line. As indicated previously, the range of angles shown in FIG. 8 represent only one embodiment of the present invention and is not intended to limit the scope thereof.  
         [0036]    Therefore, the present invention includes a method for determining a pinion bearing move to align a pinion-to-gear assembly. To determine the proper realignment move, the gear tooth is set to a proper angle below mill center line. The pinion tooth is then inserted or positioned into a pocket of the gear tooth such that the eyelet of the pinion tooth is positioned over a starting reference point. Temperature differentials recorded from the pinion gear assembly are then analyzed to determine the appropriate scale for a pinion temperature change per gradient. Simply, the highest temperature differential recorded over a series of time intervals determines which pinion temperature change per gradient scale is to be used. Once the appropriate scale has been determined, the pinion tooth is accordingly moved to correct for the differential in temperature. For example, if the pinion temperature differential for the “out of mesh” rotation is 10° F., then each gradient line of the gear tooth corresponds to 2½° F. Therefore, to increase the pinion temperature by 10° F., the pinion tooth must be moved closer to mesh four gradient lines for the “out of mesh” rotation. Conversely, if the pinion temperature for the “out of mesh” rotation is to be decreased by 10° F., the pinion tooth is moved away from the mesh four gradient lines for the “out of mesh” rotation. Moving the pinion tooth the requisite number of gradient lines to account for the temperature differentials will result in the eyelet of the pinion tooth to be repositioned. The distance of the new position of the eyelet in relation to the starting position may then be used to determine the appropriate pinion bearing move. Simply, the pinion bearing move of the pinion gear assembly required to reduce the pinion temperature differential to zero is the difference between the pinion bearing starting reference point and the end point of the pinion tooth target after correction. After determining the distance in an x and in a y direction between the final position and the initial reference position, it is necessary to determine the appropriate scale to use in determining the pinion bearing realignment move. As discussed previously, the appropriate pinion bearing move as well as relative root change may be determined based upon which temperature gradient scale that was selected for moving the pinion tooth to the final corrected position.  
         [0037]    Determining appropriate pinion bearing moves to correct pinion-to-gear alignment in accordance with the present invention are easy, quick and accurate. Furthermore, the present invention may also be used not only as an in-field product to recalibrate grinding mills and other pinion bearing assemblies, but may also be used as a teaching tool for those learning pinion gear alignments. The visual representation of the actual gear-pinion pressure angles and the pinion positions down from mill central line enables students to ascertain gear pressure angles, angles of the pinions below mill central line, and why and how pinion alignment corrections may be made. Further, those learning pinion alignment correction techniques may implement the present invention without having to input a significant amount of data into a computer program or solving a number of highly complex and often geometrical and trigometrical mathematical calculations. Further, the present invention also contemplates including a series of instructions on a reverse side of base portion  40 , FIG. 2, for instructing users on determining pinion bearing moves to correct pinion-to-gear alignments in accordance with the teachings of the present invention.  
         [0038]    Therefore, in accordance with an embodiment of the present invention, a method for determining a pinion bearing move to correct pinion-to-gear alignments for a pinion- gear assembly comprises positioning a gear tooth to a first angle and positioning a pinion tooth to a starting position. The method further includes determining a pinion temperature differential, Δt, and repositioning the pinion tooth to a corrected position based on the pinion temperature differential. The method further includes determining a distance from the starting position to the corrected position.  
         [0039]    In accordance with another embodiment of the present invention, a nomograph includes a gear tooth having at least one set of a number of temperature gradient reference lines. The nomograph further includes a pinion tooth having a pair of aligned reference points. The nomograph further includes a gradient grid having a plurality of reference points for determining a pinion adjustment move.  
         [0040]    In accordance with yet another embodiment of the present invention, a tool for realigning a pinion gear assembly is provided. The tool includes a visual representation of a gear to pinion mesh illustrating pressure angles of a gear and pinion assembly. The tool further includes an instructional manual having a set of instructions for determining one or more pinion bearing moves based on one or more pinion temperatures.  
         [0041]    The present invention has been described in terms of the preferred embodiment, and it is recognized that equivalents, alternatives, and modifications, aside from those expressly stated, are possible and within the scope of the appending claims.