Patent Publication Number: US-6986344-B2

Title: Bladeshaft assembly for a powered saw or cutting machine

Description:
FIELD OF THE INVENTION 
   This invention relates to a bladeshaft assembly for a powered cutting saw as may be used in the construction and concrete cutting applications. More particularly, this invention relates to such a bladeshaft assembly as includes an improved pulley attachment arrangement as well as improved seal configuration at the bladeshaft tube ends wherein sealed bearings reside. 
   BACKGROUND OF THE INVENTION 
   Bladeshaft assemblies as may be used in construction equipment such as concrete cutting road saws are subject to extreme wear and adverse operating conditions. For instance, the amount of concrete dust and the necessary fluid slurry for keeping the dust down, generated when such a concrete cutting saw is used to cut into highway concrete, has an extremely negative effect on the life and operating characteristics of any component in the concrete cutting machine. Constant exposure to such dust and slurry can result in the need to service and replace components on a frequent basis that at times can be on the order of requiring service every eight hours. Of course, in the construction industry, it is highly undesirable to require servicing of the equipment on such a frequent basis since any such service requirement results in a stoppage of work and can delay a project. Accordingly, it would be desirable to provide a bladeshaft assembly for a concrete cutting saw that extended the amount of time between needed service actions. 
   An additional problem in the construction or concrete cutting business is an out of tolerance condition that may occur because of the high vibration experienced during the concrete cutting operation. For instance, if the relative displacement between the pulley on the drive shaft and the pulley on the bladeshaft change due to drift in positioning of one or the other of such pulleys as may be caused by vibration, excess wear will occur to the belt connecting the two pulleys as well as the actual cutting blade itself. Accordingly, it would be further advantageous if a bladeshaft assembly could be provided that would be less susceptible to drift in component placement as may be caused by the high-vibration characteristics of the concrete cutting environment. 
   Still another problem encountered in the concrete cutting environment is the susceptibility of the dust and slurry contamination entering the sealed area where the shaft bearings reside. Under such conditions, it may again be necessary to service the cutting machine on a more frequent basis than desired and as well, may result in the costly exercise of having to replace the entire blade shaft assembly if the servicing is not done when required. Servicing the bladeshaft assembly to repair or replace the shaft bearings is further complicated by the fact that the combination of the concrete dust and the slurry can create a hardened coating over the seal and attachment arrangement that protects the sealed bearing area. Given the problem of the difficulty in accessing the sealed bearing area due to concrete dust and slurry contamination, it would be advantageous if a sealing arrangement could be provided that would allow for substantially eliminating the contamination from entering the sealed bearing area and even more beneficial, in the unlikely event contamination did enter the bearing area, a simple and reliable attachment configuration would be provided to service the bearing area without the need to replace the entire bladeshaft assembly. 
   Yet another problem that has arisen in the manufacture and maintenance of concrete cutting machines is the time-consuming and unreliable method of positioning the pulleys on the respective drive and bladeshafts so as to be assured the alignment of such pulleys is substantially accurate. A typical pulley and shaft attachment arrangement involves a pulley have a center opening that is sized slightly larger than the diameter of the shaft on which it is to be mounted. The pulley is then secured to the shaft end by means of a number of setscrews that are tightened down onto the shaft. In the manufacturing process for performing this attachment, a worker must carefully assure that the displacement of the pulley on the shaft is accurate so that the pulley aligns appropriately with the counterpart pulley from the drive shaft. This process is time-consuming, is subject to assembly error and does not provide for consistent repeatable results for all concrete saw machines that are manufactured. The problem of alignment of the pulley onto the shaft during the initial manufacturing operation is also experienced in the field where it becomes necessary to replace a worn pulley. Additionally, because there is a difference in the diameter opening of the pulley and the diameter of the shaft, by securing the set screws onto the shaft, there is a tendency to render the shaft and pulley assembly as non-centric. In other words, the outer diameter of the pulley will not be concentric with the center longitudinal axis of the shaft. The effect of such non-centricity is that the cutting blade will be exposed to significantly more vibration and will not be as balanced as would be possible if the pulley and the blade shaft were concentric. Based on the problems associated with accurately and consistently aligning the pulley on the shaft, it would be advantageous if a better arrangement for attaching the pulley onto the shaft were developed, such better arrangement assuring that the results in both the manufacturing process and the service operation are accurate, repeatable and can be achieved in a simple and efficient manner. 
   SUMMARY OF THE INVENTION 
   The present invention provides an improved bladeshaft assembly for use with a cutting machine as may be used in the concrete and construction industries. The bladeshaft assembly of the present invention includes a hollow tubular housing member. A shaft member extends coaxially through the tubular housing member and has at least one end that extends outwardly of the tubular housing member. At least one bearing member is disposed in surrounding relation to a portion of the shaft member. A sealing arrangement is disposed around the at least one end of the shaft member as it extends outwardly of the tubular housing member. A pulley member is mounted on the at least one end of the shaft member that extends outwardly of the tubular housing member. A tapered fit is formed cooperatively between the pulley member and the at least one end of the shaft member so as to enable a press fit relation between the pulley member and at least end of the shaft member. First and second gauge points are formed respectively between the pulley member and the at least one end of the shaft member; the first and second gauge points engage one another so as to establish a predetermined placement of the pulley member on the at least one end of the shaft member. 
   In an alternate embodiment of the invention, the sealing arrangement disposed at the opening of the tubular housing member adjacent to where the bearing members are disposed includes a cover seal member and a slinger shaft member that are cooperatively formed so as to provide a labyrinth path therebetween. A re-lubrication path is formed in one of the cover seal member and the slinger shaft member so as to allow the introduction of lubrication into the labyrinth thereby providing that any contaminant materials that may have worked its way toward the sealed bearings, can be purged. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     These and further features will be apparent with reference to the following description and drawings, wherein, 
       FIG. 1  is an elevational view of a blade shaft assembly constructed in accordance with prior art teachings. 
       FIG. 2  is an elevational view of a concrete cutting machine that incorporates the bladeshaft assembly constructed in accordance with the present invention. 
       FIG. 3  is an elevational view in section of the bladeshaft assembly constructed in accordance with the present invention. 
       FIG. 4  is an elevational view in section of one end of a bladeshaft assembly constructed in accordance with the present invention. 
       FIG. 5  is an exploded elevational view in component form of the bladeshaft assembly constructed in accordance with the present invention. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   As seen in  FIG. 1 , the bladeshaft assembly constructed according to the teachings of the prior art includes a pulley  10  mounted on a shaft  12 . Typically, the pulley  10  is secured to the shaft  12  by a number of set screws (not shown) that are tightened by way of an allen head fitting on the set screw. The shaft  12  extends through an end cap  14  that is fastened to the end of a bladeshaft tube  16 . The end cap  14  is typically secured to the bladeshaft tube  16  by means of set screws  18 . An end seal  20  is located inside of the end cap  14  and acts to prevent some contaminants from entering the region where bearings  22  are disposed. As discussed, the problems with such a prior art arrangement are that it is difficult to manufacture and service the bladeshaft assembly under the difficult environmental conditions that concrete and heavy construction cutting is done. 
   As seen in  FIG. 2 , a concrete cutting saw  30  on which the bladeshaft assembly  50  of the present invention is mounted includes a baseframe  32  on which a control panel  34  is mounted on the rearward side and an engine  36  is mounted adjacent thereto. The engine powers a drive train  38  from which extends a drive shaft  40 . The control panel  34  includes operator controls (not shown) for allowing the operator to control the cutting blade  48  and the engine  36  in a manner that is known to those skilled in the art. 
   A drive pulley  42  is mounted on the end of the drive shaft  40 . The pulley  42  of the drive shaft  40  is connected to the bladeshaft assembly  50  by means of a belt  44 . A belt cover  46  can be disposed over the belt  44  so as to protect the belt  44  from the harsh conditions under with the concrete cutting saw  30  operates. A cutting blade  48  can be mounted on the end of the bladeshaft assembly  50 . It should be noted that the concrete cutting saw  30  can accommodate the mounting of a cutting blade  48  on either the left or the right side of the bladeshaft assembly  50 . This feature is necessary so that the concrete cutting saw operator has the ability to cut from either the left or the right side of the cutting machine  30 . 
   An axle and wheel assembly  52  is mounted on the bottom portion of the baseframe  30 . As is known in the art, the axle and wheel assembly  52  can be powered by the engine  36  or other motive force to allow for driving the cutting machine  30  forward or backward. Control handles  54  extend from the control panel  34  and allow the operator the ability to maneuver the cutting machine  30 . 
   As seen in  FIG. 3 , the bladeshaft assembly  50  includes a tubular member  56  through which a shaft member  58  extends coaxially. The tubular member  56  has raised end portions  60  disposed on opposite ends thereof. The raised end portions  60  have a larger inner diameter opening than the center portion  64  of the tubular member  56 . The raised end portions  60  are sized so as to accommodate the diametric size of the bearing members  66  that are disposed therein. As shown in  FIG. 3 , a pair of bearing members  66  is disposed at each end. The bearing members  66  can be of a type that are pre-packed and sealed and require little if any further lubrication over the lives thereof. As will be described more fully with respect to  FIG. 4 , the raised end portions  60  and the bearing members  66  residing therein are sealed at their respective ends by flange end covers  68 . Disposed along shaft member  58  adjacent the flange end covers  68  are respective shaft slinger members  70 . Both the flange end covers  68  and the corresponding shaft slinger members  70  are machined so as to have a center opening  72  formed therein; the shaft member  58  extends through the center openings  72  so as to extend outwardly of the tubular member  56  and end cover configuration. 
   At a position along the shaft member  58  as it exits each end of the tubular member  56  and end cover configuration, a pulley member  74  is disposed thereon. With reference now to  FIG. 4 , it can be seen that the inner opening  76  of the pulley member  74  is tapered. The shape and angle of taper of the inner opening  76  is machine controlled so as to achieve a uniform dimension that is consistent for all shaft members  58  used in the bladeshaft assemblies  50 . As further seen in  FIG. 4 , the taper of the inner opening  76  does not begin at the immediate point of entry but instead begins at gauge point  78 . The distance from the initial opening into inner opening  76  to the gauge point  78  is also accurately controlled during the machining operation for the pulley member  74 . In the same way that the dimensions of the inner opening  76  of pulley member  74  is maintained to a high degree of accuracy, the taper of the shaft end  80  is also similarly controlled. Specifically, as seen in  FIG. 4 , the shaft end  80  of shaft member  58  is tapered in a corresponding manner to the taper of the inner opening  76  of pulley member  74 . In addition, a shaft gauge point  82  is formed on shaft member  58  in a manner so as to coincide with gauge point  78  of the inner opening of pulley member  74 . 
   Given the relationship between the taper dimensions of the shaft end  80  and the inner opening  78  of pulley member  74  as well as the corresponding placement of the gauge point  78  and the shaft gauge point  82 , it can be appreciated that during the manufacturing process for bladeshaft assembly  50 , a repeatable and accurate placement of the pulley member  74  onto shaft member  58  is achieved by means of a press fitting. Additionally, by press fitting the pulley member  74  onto shaft member  58 , the need for set screw attachment is avoided and problems of non-centricity between the pulley outer diameter and shaft member  58  axis, do not occur. 
   Once the pulley member  74  has been press fit onto the tapered shaft end  80 , a key member  84  can be inserted into a keyed slot formed cooperatively in one or both of the tapered shaft end  80  and the inner opening  78  of pulley member  74 . Of course, the use of a key type of locking mechanism is optional and is not essential to achieve the benefits of the bladeshaft assembly of the present invention. 
   An inner flange member  86  is disposed at the end of the shaft end  80  adjacent the outer edge of pulley member  74 . Inner flange member  86  can also include an optional keyed slot area so as to be joined with the pulley member  74  and tapered shaft end  80 . Inner flange member  86  can include a forward edge portion  88  that fits within a slot  90  formed in the outer edge of pulley member  74 . By securing the inner flange member  86  to the tapered shaft end  80  along with the outer flange member  92 , the press fit relationship between the pulley member  74  and end shaft  80  can be further supplemented. The securing device  94  is shown as a threaded bolt arrangement but could be any other fastening means as is known to those skilled in the art of fasteners. 
   A blade key  96  extends between the inner flange member  86  and the outer flange member  92  and is effective so that when a cutting blade (not shown) is mounted between the two flanges  86 ,  92 , it is secured in place. 
   Returning now to the sealing arrangement between the flange end cover  68  and the shaft slinger  70 , it can be seen that a labyrinth  98  is formed therebetween. The labyrinth  98  is effective so as to present as difficult of a path as possible for contaminants such as dust and slurry from reaching the sealed bearings  66 . In order for any such contaminants to reach the bearings  66 , it must turn several corners, fit through the slight gap between the shaft member  58  and the opening  72  in the flange end cover  68 , as well as an optional O ring or other sealing member  102  disposed between the bearings  66  and the flange end cover  68 . As a further precaution to preventing contaminants from reaching the bearings  66 , a re-lubrication path  100  is formed in the flange end cover  68 . The re-lubrication path allows for lubrication to be pushed through the labyrinth  98  in a way to push any contaminants in the labyrinth back out through the opening to the labyrinth  100  formed between the flange end cover  68  and the shaft slinger  70 . 
   With reference now to  FIG. 5 , the bladeshaft assembly  50  is constructed in a way so as to dispose the bearings  66  into the raised ends  60  of the tubular member  56 . It should be noted that by sizing the raised ends  60  larger than the diameter of the tubular member  56 , the assembler of the bladeshaft assembly  50  can utilize the inner surface  106  of the raised end  60  as a leverage point for a tighter press fit of the pulley member  74  onto the shaft end  80 . 
   As further seen in  FIG. 5 , the flange end cover  68  is mounted to the raised end  60  by means of through bolts  104  that extend through the raised ends  60  and are fastened by conventional nut/washer arrangements  108 . In this manner, should there be a need to gain access to the sealed bearings  66 , it is possible to remove the flange end cover  68  even under conditions where the concrete dust and slurry contamination have formed a hardened coat of contaminants around the opening to the bearings  66 . In prior art examples of bladeshaft assemblies such as shown in  FIG. 1 , once the contaminants have hardened around this area, it is nearly impossible to gain access to the sealed bearings thus necessitating a complete replacement of the bladeshaft assembly. 
   Although the hereinabove described embodiment of the invention constitutes the preferred embodiment, it should be understood that modifications can be made thereto without departing from the scope of the invention as set forth in the appended claims.