Abstract:
A grinder in a tire uniformity machine that receives a tire for testing, the grinder including an arm received in bearings; a grinding head supported on the arm, the grinding head having a rotatable grinding stone and a motor causing the rotation of the grinding stone; and a linear actuator operatively engaging the arm to selectively cause axial movement thereof causing the grindstone to selectively contact the tire.

Description:
RELATED PATENT APPLICATIONS 
     Patent application Ser. No. 09/678,242, filed Oct. 4, 2000, entitled Dual Grindstone. 
    
    
     FIELD OF THE INVENTION 
     The present invention generally relates to tire uniformity machines. The present invention more particularly relates to a grinding apparatus in a tire uniformity machine. Most particularly, the present invention relates to a linearly actuated grinding apparatus used for removing material from tires in a tire uniformity machine. 
     BACKGROUND OF THE INVENTION 
     In tire uniformity machines, a tire is tested by rotating it at various speeds to ensure that the tire has been constructed and performs within quality standards. During this testing process, the tire is rotated and the tire uniformity machine examines the tire&#39;s shape and surface characteristics to a high degree of accuracy. At times, during this examination, the tire uniformity machine detects irregularities in the tire. Any irregularity in the surface and shape of the tire may be corrected by removing material from appropriate portions of the tire. 
     To remove material, known tire uniformity machines typically employ a grinder having a single cylindrical grindstone rotating in relations to the rotation of the tire. As the tire rotates, the grindstone is selectively brought into contact with the tire to remove material. 
     In known grinders, the application of the grindstone occurs in a rotary fashion. The typical grinder has a pivoting arm on which the grindstone and its motor are mounted. Often a motor and gear box arrangement is used to control the speed and direction of rotation of the grindstone. The motor is then connected to the grindstone by belts or chains and a series of pulleys or sprockets. As will be appreciated, the motor and gear box are bulky and the positioning of this unit is limited. In fact, the typical motor housing projects to such an extent that the confines of the tire uniformity machine prevent the grindstone from being actuated in a linear fashion. 
     To overcome this, known tire uniformity machines attach the motor distally from the grinder on an arm that houses the drive belt or chain. In this way, the motor is located away from the instrumentation, the load wheel, and other devices that must be placed proximate to the test tire, where there is more space. The arm is mounted on a pivot such that the motor housing moves radially in a limited area. The pivot is located between the motor and grindstone, and the arm rotates under the force of a hydraulic cylinder attached to the arm on one side of the pivot. The typical hydraulic cylinder acts transversely of the arm and thus is mounted on a separate frame member than the frame member on which the arm pivots. So mounted, the hydraulic cylinders reduce visibility and access to the grinder and the area surrounding the grinder. 
     Due to the rotation of the arm, the grinder may not be aimed directly at the tire center. In other words, the center line and the contact point of the grinder travel in an arc in an attempt to tangentially contact the tire. As will be readily understood, initiating contact with the tire in this manner makes it difficult to make good, accurate contact in a repeatable manner. Further, the housing of the grinder must be adjusted to clear the machine housing and attempt to make proper contact between the grinder and the tire. Specifically, the grinder housing often is connected to a vacuum supply to remove particles created by the grinding process, and this housing must be made to closely fit the grindstone. Since this housing closely fits about the grindstone, in these devices, simple rotation of the arm may cause the housing to contact the rotating tire. As will be appreciated, such contact could significantly damage the grinding apparatus and may cause damage to the tire. 
     To avoid such contact and to better position the grindstone to remove material, known devices adjust the position of the housing and grindstone by rotating the housing relative to the arm. To make this adjustment, known devices incorporate a series of linkages. In some cases, as many as five linkages may be used. Due to machining tolerances, each link is a source of error. When multiple links are used, this error is compounded making it more significant in terms of accurate removal of the tire material. These errors make it difficult to achieve good contact with the tire. 
     SUMMARY OF THE INVENTION 
     In light of the current status of the art, it is an object of the present invention to provide a grinder that reduces the error associated with the use of multiple linkages. 
     It is a further object of the present invention to linearly actuate the grinder into contact with the tire. 
     In view of at least one of these objects, the present invention provides a grinder in a tire uniformity machine that receives a tire for testing, the grinder including an arm received in bearings; a grinding head supported on the arm, the grinding head having a rotatably grinding stone and a motor causing the rotation of the grinding stone; and a linear actuator operatively engaging the arm to selectively cause axial movement thereof causing the grindstone to selectively contact the tire. 
     The present invention further provides a grinder in a tire uniformity machine receiving a tire having a central axis for testing, the grinder including a support member; linear bearings mounted on the support members; an arm carried on the bearings and moveable toward or away from the tire; a grinding head supported on an end of the arm proximate the tire, the grinding head having a pair of rotatable grindstones adapted to contact the tire and at least one motor causing the rotation of the grindstones; and a linear actuator operatively engaging the arm causing the grindstone to move linearly to contact the tire. 
     The present invention further provides a method of removing material from a tire in a tire uniformity machine that rotates a tire for testing, the method including providing an arm; carrying a rotatable grindstone on an end of the arm; supporting the arm on linear bearings; driving the arm linearly toward the tire causing the grindstones to contact the tire; and rotating the grindstone as the grindstone contacts the tire. 
     The present invention further provides a grinding head in a grinder for a tire uniformity machine having a frame, the tire uniformity machine receiving a tire for testing within the frame, the grinding head including a grindstone rotatably supported in a shroud and directly driven by a motor mounted adjacent to the grindstone. 
     It accordingly becomes a principal object of this invention to provide a tire uniformity machine grinder of the character above-described with other objects thereof becoming more apparent upon a reading of the following brief specification considered and interpreted in view of the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a top plan view of a grinder in a tire uniformity machine according to the present invention. 
     FIG. 2 is a side elevational view thereof. 
     FIG. 3 is a front elevational view thereof. 
     FIG. 4 is a fragmented sectional view of the grinding head and motor as might be seen along line  4 — 4  in FIG.  1 . 
    
    
     DETAILED DESCRIPTION 
     A grinder according to the present invention is generally referred to by the numeral  10  in the accompanying drawing figures. Grinder  10  is used to remove material from a tire T. Tire T is located in a tire uniformity apparatus and accordingly is rotatably mounted within the tire uniformity machine. During operation of the tire uniformity machine, tire T may be caused to rotate, by an appropriate drive mechanism, such that the tire T rotates about a central axis CA. The tire uniformity machine causes the tire T to rotate to evaluate aspects of the tire T including its surface characteristics. 
     To that end, a load wheel, which is moved into and out of contact with the rotating tire, and various sensors may be employed to obtain information about the tire&#39;s integrity, shape, and surface qualities. Irregularities in the surface S of tire T may be corrected by appropriate removal of material from the surface S. To remove material, grinder  10  is selectively brought into contact with the surface S of tire T. 
     Grinder  10  is suitably supported proximate to tire T to affect such contact, for example, by a frame F. Frame F may be an independent support or a part of the tire uniformity machine, as shown. Grinder  10  generally includes a support member  12  attached to frame F. As shown in FIG. 1, support member  12  may be provided with a pivot  14  to allow for radial adjustment of support member  12  relative to the frame F. Pivoting of the support member  12  allows the grinder  10  to be aligned with the tire to ensure proper contact between the grinder  10  and tire T. The center line CL of grinder  10  may be aligned with the central axis CA of tire T to achieve simultaneous contact of the grindstones of grinder  10 . 
     Once aligned, the grinder  10  may be positively locked into place such that it remains aligned during the grinding process. To that end, support member  12  may be provided with a pivot stop  11  extending from support  12 . Further, a bumper  13  and shim  15  may be provided between the frame and support member  12  to adjust spacing. It will be appreciated that, shim  15  and bumper  13  may be located between the frame F and pivot stop  11 . Thus, the radial position of support member  12  may be adjusted by varying the size of the shim  15  and then the grinder  10  may be locked against Frame F. Alternatively, a dynamic adjustment system may be used incorporating appropriate sensors for determining the position of the grinder  10  relative to the tire T and its center line CL and an appropriate actuator, responsive to the sensors, for changing the radial position of the grinder  10  by movement of support member  12  relative to the frame F. In this way, the grinder  10  may be appropriately aligned with respect to the tire T. Preferably, the center line CL of grinder  10  will be aligned with the axis CA of the tire T. 
     One or more arms  16  are held in spaced relation by support member  12 . Arms  16  are supported on bearings  18  that facilitate substantially linear movement of the arms  16  toward and away from the tire T. Bearings  18 , as shown in FIG. 3, are linear bearings and may include rollers  19  suitably mounted on support member  12 . Rollers  19  are vertically aligned to receive edges  21  of arms  16 . Offset bearings  18 , such as those shown in FIG. 3, may be employed and located at either side of the edges  21  of arm  16  to help resist forces acting on the arm  16  and maintain the position of the arm  16 . Referring to FIGS. 4 and 5, bearings  18  may be located in fore and aft positions on the support member, and longitudinally aligned to guide the arm  16  upon actuation. 
     The arms  16  are actuated by a suitable linear actuator generally referred to by the numeral  20 , including fluid driven actuators, such as, hydraulic or pneumatic cylinders, motor driven actuators, electric actuators and the like. In the embodiment shown, actuator  20  includes a pair of cylinders  22  that expand to drive the arms  16  toward tire T and retract to pull the arms  16  away from the tire T. 
     As previously discussed, the manipulation of grinder  10  may be controlled by various methods available in the art. For example, hydraulic or pneumatic cylinders  22  may be employed to extend and retract the arm  16  carrying grinding heads  30 . In such a case, supply lines (not shown) carrying fluid from a fluid supply may be used to selectively direct fluids to the cylinders  22  and to apply a motive force. The activation of these cylinders  22  may be coordinated by sensor  37  located in sensing relation to tire T or grinding head  30 . The sensor  37  being in communication with a controller  39  that controls the fluid supply to the cylinders  22 . In the embodiment shown, a servo valve  41  is used to control the flow of fluid passing through a manifold  43  that supplies the cylinders  22 . As a result of the flow control, position of the grinding head  30  relative to the tire T is controlled. 
     Additionally, the position of grinding heads  30  relative to each other and tire T may be adjusted as required by the particular tire T. To that end, arms  16  are provided with a separation adjuster  24  and a tilt adjuster  26  engaging ends  28  of arms  16 . The ends  28  may be made pivotable to allow spacing of grinding heads  30  relative to each other or arms  16 . To provide further manipulation of grinding head  30 , grinding head  30  may be pivotally attached to ends  28  of arms  16 . As best shown in FIG. 7, grinding head  30  may be pivotally mounted between spaced members  29  of ends  28  and rotate or tilt therebetween. While the grinder  10  may be oriented in any position and the tilting may be varied accordingly, the grindstone  32  substantially lies in a plane parallel to the plane of the tire T. When the grindstone  32  is tilted, the grindstone  32  deviates from this plane and generally rotates between a plane substantially parallel to that of the tire T to a plane substantially perpendicular to that of the tire T. As can be appreciated, the amount of tilt may be limited by appropriate stops or limiters, and the tilt adjuster  26  may control the amount and rate of tilt. Tilt adjuster  26  extends from arm  16  or end  28  to grinding head  30  to control the amount of tilt of grinding head  30 . To limit the range of motion of grinding head  30 , an adjustable pivot lock  31  may engage grinding head  30 . In this way, the adjustment members  24 ,  26  may be used to alter the spacing of grinding head  30 , or to tilt the grinding heads  30  relative to the tire T and arms  16 . Various adjustment members  24 ,  26  may be used including mechanical actuators such as threaded members, gears, ratchet members, fluid cylinders, or cams; or electric actuators including linear rails. Alternatively, spacing and tilt may be adjusted by moving the grinding heads  30  on the frame F, or support member  12 . 
     Grinding heads  30  are supported on ends  28  of arms  16  and generally include a grindstone  32  driven by at least one motor  35 . Further, the motor  35  is supported adjacent to a shroud  40  and may be mounted to the ends  28  of arms  16  or to the shroud  40  itself. The grindstone  32  is operatively attached to the motor  35  and may be driven directly thereby. By directly driving the grindstone and eliminating the belts and pulleys used in known systems, the size of the motor may be reduced. The elimination of the belt or chain system and the reduced size of the motor  35  results in reduced inertia of motor  35 . This reduced inertia allows the motor  35  to quickly reverse directions, when a reversible motor  35  is used. In the embodiment shown, a reversible motor  35  is used to directly drive the grindstone  32 . By reversing the grindstone  32  quickly the directly drive motor  35  may significantly reduce processing time, when reversal is necessary. 
     As best shown in FIG. 7, the motor  35  may be secured adjacent to the shroud  40 . The shaft  42  of motor  35  extends through an opening formed within the shroud and extends into the grinding chamber  44 , defined by the shroud  40 , where it is coupled to the grindstone  32 . Power to the motor  35  is supplied conventionally by cables, which may connect to the motor  35  at a junction box  46 . To protect the components of motor  35 , a housing  48  is provided to substantially cover the exposed surfaces of motor  35 . 
     To help contain and remove these particles, the shroud  40  closely fits over grindstone  32 . The shroud  40  may generally define an opening  50  located radially outwardly from the axis of rotation of grindstone  32  and spaced therefrom such that the grinding surface  52  of grindstone  32  is exposed. Further, shroud  40  may define an opening  55  axially spaced from the grindstones  32  to allow access to the interior of shroud  40  for purposes of cleaning or to repair or replace the grindstone  32 . During operation, the axially spaced opening  55  may be closed by a suitable cover  58 . 
     The shroud  40  may be provided with a nozzle  60  attached to a vacuum source for the removal of particulate created during the grinding process. When the shroud  40  has a curved wall  61 , as shown in FIG. 1, the nozzle  60 . may open into chamber  44  tangentially, as best shown in FIG. 3. A nozzle  60  may be fluidly connected to the vacuum source by a hose  62 . To further aid in the removal of particulate, a jet nozzle  64  may direct a supply of fluid toward the tire T to attempt to expel particulate lodged within the treads of tire T or on the surface S thereof. Jet  64  is fluidly connected to a supply distal from the grindstone  32 . Jet  64  may be located outside of or within shroud  40 . Preferably, jet  64  is located near the tire T and may be positioned such that it is centrally located within the vacuum stream created by the vacuum source, as discussed in copending application referred to above. 
     The shroud  40  is open toward the tire T exposing a portion of the grindstone  32  to the tire T. The sensor  37  may be mounted on the shroud  40  or proximate thereto to determine the amount of material removed from the tire T. Sensor  37  communicates with controller  39  which accordingly controls the movement of grindstone  32 . 
     When removing material from the tire T, contact is made by grindstone  32 . Depending on the particular tire T and desired grinding effect, the rotation of grindstone  32  may be changed relative to the direction of rotation of tire T. 
     As previously discussed, the position of the arms  16  and thus the grinding heads  30  may be controlled by selectively extending or retracting the arms  16  by way of the linear actuator  20 . Extension of the arms  16  drives the grinding head  30  in a substantially straight line to place grindstone  32  of the grinding head  30  into contact with surface S of tire T. In this way, the grinding head  30  is directly driven by a single actuator  20  into contact with the tire T. Once sufficient material is removed from the tire T, the linear actuator  20  retracts the arm  16  pulling the grindstone  32  away from the tire T. 
     Since grinding may occur at the treads, sidewall, or the shoulder therebetween, the grinding head  30 , shroud  40 , and motor  35  may be made pivotable about an axis  70 . In the embodiment shown, the end  28  of the arm  16  attaches to the shroud  40  of grinding head  30  at a pair of pivot points  72 ,  74  located on either side of the shroud  40 . As shown in FIG. 5, the pivot points  72 , 74  may be located generally at the base  76  of the motor  35  and in substantial alignment with the top portion  78  of the shroud  40 . A tilt adjuster  80  may extend between the arm  16  and the housing of the motor  35 , wherein displacement of the tilt adjuster  80  pivots the grinding head  30  about the axis  70  defined by pivot points  72 ,  74 . In this way, the grindstone  32  may be actuated to contact the sidewall, shoulder, or tread in substantially parallel relation to the surfaces if desired. It will be appreciated that depending on the type of irregularity that is to be removed from the tire, the grinding surface  52  of the grindstone  32  may be positioned at various angles. 
     It will further be appreciated that it may be desirable to obtain different surface characteristics for different tires T or portions thereof. Consequently, differing grinding treatment of tires T may be required as various tires T are tested at the tire uniformity machine. To accommodate the variance in tires T, the speed and direction of rotation of grindstone  32  may be varied either through controlling the speed of the motor  35 , or through the use of other known means including pulley or gear differentials. Further, grindstone  32  having a different grit may be selected to obtain a desired surface characteristic. 
     It will still further be appreciated that the grinding head  30  and motor head  35  may be retrofit to existing grinders with little or no modification. 
     While a full and complete description of the invention has been set forth in accordance with the dictates of the patent statutes, it should be understood that modifications can be resorted to without departing from the spirit hereof or the scope of the appended claims. 
     Thus, the invention has been illustrated and described with regard to a grinding head carrying dual grindstones but the linear actuation with respect to the tire and the direct drive of the grindstone would also have application to a grinding having only one grindstone.