Abstract:
An apparatus for forming a continuous preparation ply of the type used to make vehicle tires from preparation ply sections having nonmetallic cords. An infeed conveyor successively feeds the preparation ply sections to a butt splicing machine that joins the ends of the two preparation ply sections to form a butt joint. A gum strip applier receives the continuous preparation ply from an outfeed conveyor and applies a gum strip over the butt joint. A method is provided for forming a continuous preparation ply by first automatically forming a butt joint, and thereafter automatically placing a gum strip on the butt joint.

Description:
FIELD OF THE INVENTION 
     This invention relates generally to apparatus and method for producing a continuous preparation ply material for making tires and more particularly, to an apparatus and method for making a continuous web of preparation ply material having transverse nonmetallic reinforcing cords. 
     BACKGROUND OF THE INVENTION 
     In the construction of a radial ply tire, a carcass consisting of one or more preparation plies of elastomeric material is built up on a generally cylindrical drum. The preparation ply is applied so that reinforcing cords run from bead to bead in a direction that is generally parallel to the axis of the drum. Thus, prior to making the carcass, the preparation ply with the transversely extending reinforcing cords must first be made. 
     It is known to manufacture the preparation ply by first producing a sheet of elastomeric material in which reinforcing cords extend longitudinally. During production, the sheet of elastomeric material passes between calendering rolls. The calendered sheet of material is then cut into quadrilateral, for example, rectangular pieces, reoriented and the calendered edges are then spliced together to form a continuous strip of preparation ply material. The reorientation results in the reinforcing cords extending substantially parallel to the splice joints and substantially perpendicular to the longitudinal direction of the preparation ply strip. 
     If the elastomeric material has metallic reinforcing cords, the lateral calendered edges of the material have relatively straight and uniform edges. Thus, in the manufacture of a preparation ply that has metallic reinforcing cords, the adjacent ends of the strips are placed in direct opposition and brought together without any overlap of the ends to form an end-to-end or butt joint splicing the two ends together. Thus, the ends are, held together only by the tackiness of the uncured rubber over the area of the adjacent ends. Metallic reinforcing cords provide a relatively linear calendered edge that is suitable for a butt splice bond created by the tackiness of the elastomeric material. 
     However, if the elastomeric material has nonmetallic reinforcing cords, the lateral calendered edges of the material are not straight but undulating. Such curved calendered edges provide a nonuniform and variable gap between the adjacent ends of the pieces and thus, are generally not considered suitable for a butt splice. Consequently, although a butt splice would be preferred in the manufacture of a preparation splice, an overlapping splice is often used to join the cut pieces having nonmetallic reinforcing cords. 
     Therefore, there is a need for improved apparatus and method for automatically making a preparation ply with butt splices. More particularly, there is a need for apparatus and methods for automatically butt splicing together a preparation ply having nonmetallic reinforcing cords. 
     SUMMARY OF THE INVENTION 
     In a first embodiment of the present invention, an apparatus is provided that automatically butt splices a preparation ply having metallic or nonmetallic reinforcing cords. The apparatus is relatively simple in design and less expensive than other machinery used to butt splice a preparation ply. The apparatus of the present invention provides a high quality butt splice regardless of the reinforcing cord material and therefore, is especially useful in making a preparation ply having nonmetallic reinforcing cords. 
     More specifically, the first embodiment of the invention provides an apparatus for forming a butt joint between ends of first and second plies to splice the plies together. The apparatus has pairs of upper racks that extend end-to-end; and each pair of upper racks has first and second upper racks that are movable with respect to each other. In addition, pairs of lower racks extend end-to-end adjacent the pairs of upper racks; and each pair of lower racks has first and second lower racks that are movable with respect to each other. The first and second lower racks support ends of first and second plies, respectively. A clamp drive is connected to the pairs of upper racks and is operable to move the upper racks toward the lower racks to clamp the ends of the first and second plies between the upper and lower racks. An engagement drive is connected to the upper and lower racks and is operable to simultaneously move all of the first and second racks with respect to each other to firmly press the ends of the first and second plies together, thereby forming a butt joint splicing the ends of the first and second plies together. 
     In another embodiment of this invention, a method is provided for positioning an end of a first material ply section over teeth of the first lower racks and positioning an end of a second material ply section over teeth of the second lower racks. Next, the first and second material ply sections are clamped between the pairs of upper racks and the pairs of lower racks. Then, the teeth of all the first upper and lower racks are simultaneously engaged with the teeth of all the second upper and lower racks to firmly press the ends of the first and second material plies together to form a butt joint that splices the first and second material plies together. 
     In a second embodiment of the present invention, an apparatus is provided that automatically applies a gum strip to a butt joint joining two preparation plies together. The apparatus is fast, reliable and automatically operable with the butt splicer described herein and therefore, is especially useful in making a preparation ply having nonmetallic reinforcing cords. 
     More specifically, the second embodiment of the invention provides an apparatus having a conveyor for providing a gum strip of a desired length. A transfer device then automatically removes the gum strip from the conveyor and places the gum strip on the butt joint. 
     In a further embodiment of this invention, a method is provided for applying a gum strip over a butt joint splicing ends of first and second preparation plies by first providing a gum strip having a desired length and then, automatically placing the gum strip on the butt joint. 
     In a third embodiment of the present invention, an apparatus is provided that automatically forms a continuous preparation ply of the type used to make vehicle tires from preparation ply sections having nonmetallic cords. Being able to economically, efficiently and reliably butt splice preparation plies provides a higher quality tire manufacturing process. 
     More specifically, the second embodiment of the invention provides an apparatus having an infeed conveyor for successively feeding the preparation ply sections, and a butt splicing machine that receives the preparation ply sections from the infeed conveyor. The butt splicing machine joins the ends of the two preparation ply sections to form a butt joint splicing the two preparation plies together to form a continuous preparation ply. An outfeed conveyor feeds the continuous preparation ply from the butt splicing machine, and a gum strip applier applies a gum strip on the butt joint of the continuous preparation ply on the outfeed conveyor. 
     In another embodiment of this invention, a method is provided for forming a continuous preparation ply by first automatically forming a first butt joint splicing two preparation plies together to form a continuous preparation ply having nonmetallic cords that extend in a direction substantially parallel to the butt joint. Thereafter, a gum strip is automatically placed on the first butt joint. 
     These and other objects and advantages of the present invention will become more readily apparent during the following detailed description taken in conjunction with the drawings herein. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic illustration of a nonmetallic cord preparation ply manufacturing line having a butt splicer and gum strip applier in accordance with the principles of the present invention. 
         FIG. 2  is a side view of the butt splicer and the gum strip applier of  FIG. 1 . 
         FIG. 3  is a side view of the butt splicer of  FIG. 2 . 
         FIG. 4  is a partial perspective view of a portion of the butt splicer of  FIG. 2  that illustrates the plurality of pairs of upper and lower racks. 
         FIG. 5  is an end view of the butt splicer of  FIG. 2 . 
         FIGS. 6 and 6A  are schematic block diagrams of a control system used to control the operation of the butt splicer and gum strip applier of  FIG. 1 . 
         FIG. 7  is a flowchart of a subroutine implemented by the control system of  FIG. 6  for positioning a preparation ply piece prior to a butt splicing cycle. 
         FIGS. 8–8C  are end views illustrating different states of racks on the butt splicer of  FIG. 1  in executing the butt splicing cycle of  FIG. 6 . 
         FIG. 9  is a flowchart of a subroutine implemented by the control system of  FIG. 6  for butt splicing the preparation ply materials. 
         FIG. 10  illustrates how the upper pairs of racks are nonrigidly mounted in jaw mounting brackets on the butt splicer of  FIG. 2 . 
         FIG. 11  is an end view of the gum applier of  FIG. 2 . 
         FIG. 12  is a side view of the gum applier of  FIG. 2 . 
         FIG. 13  is a partial top view of the gum applier of  FIG. 2  illustrating the horizontal drive components. 
         FIG. 14  is a partial end view of the gum applier of  FIG. 2  illustrating the vertical drive components. 
         FIG. 15  is a flowchart of a subroutine implemented by the control system of  FIG. 6  for cutting a gum strip to length. 
         FIG. 16  is a flowchart of a subroutine implemented by the control system of  FIG. 6  for picking up the gum strip with the vacuum head. 
         FIG. 17  is a flowchart of a subroutine implemented by the control system of  FIG. 6  for applying the gum strip with the vacuum head. 
         FIG. 18  is a state diagram illustrating the operation of the control system of  FIG. 6  for simultaneously operating the butt splicer and gum strip applier of  FIG. 2 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to  FIG. 1 , in a preparation ply manufacturing line  20 , a strip of calendered material  22  is fed from calender rolls (not shown) in a known manner. The calendered material  22  is about 0.040–0.060 inch thick and has cords  24  made from a nonmetallic material, which extend longitudinally generally parallel to the calendered edges  26 . The nonmetallic cords  24  being less rigid than metallic cords result in the calendered edges  26  being nonlinear and undulating. The calendered material is fed by a conveyor  28  past a cutter  30 , which cuts the calendered material to desired lengths, depending on the application. The resulting rectangular pieces  32  are then transferred onto a transverse infeed conveyor  34 . The pieces are then conveyed in a downstream direction  35  to a butt splicing machine  36  that forms butt joints  40  between the calendered edges  26  of the cut pieces  32  to form a continuous preparation ply strip  38 . The butt joints  40  are reinforced by respective gum strips  42  that are placed over the joints  40  by a gum strip applier  44 . The resulting continuous preparation ply strip is collected on windup rolls  43  in a known manner. The continuous preparation ply strip  38  has nonmetallic cords  24  that are substantially parallel to the butt joints  40  and gum strips  42  and are transverse to a longitudinal axis  46  of the preparation ply strip  38 . 
     For purposes of this description, the term “downstream” is used to identify the direction of motion of the preparation ply material  38  through the butt splicer  36  and gum strip applier  44 , that is, from right to left as viewed in  FIG. 1 . The term “upstream” is used to designate a motion in an opposite direction. Components on the butt splicer  36  that are identified as “downstream” are located closer to the gum strip applier  44  than components identified as being “upstream”. 
       FIG. 2  is a side view of a portion of the preparation ply manufacturing line  20 , a strip of calendered material  22  that includes the infeed conveyor  34 , butt splicer  36  and gum strip applier  44 . It should be noted that except for the butt splicer  36  and gum strip applier  44 , all of the elements of  FIG. 1  are known and used in the tire manufacturing industry. It should also be noted that preparation equipment  48  for the gum strip applier  44 , which feeds the gum strip from a roll and separates and winds up a covering over the gum strip adhesive is also known. 
     Referring to  FIGS. 4 and 5 , the butt splicing machine  36  has a frame  72  that supports floating tables  70  on both the upstream and downstream sides of the butt splicer  36 . Pairs of upper racks  50  and pairs of lower racks  52  are mounted to extend transversely across the width of the butt splicing machine. Each pair of upper racks  50  is comprised of a nonpivotable, upstream rack  54  having teeth  56  that are engageable with teeth  58  of a pivotable, downstream rack  60 . Similarly, each pair of lower racks  52  is comprised of a nonpivotable, upstream rack  62  having teeth  64  that are engageable with teeth  66  of a pivotable, downstream rack  68 . The pairs of lower racks  52  are fixed in elevation immediately adjacent the table  70  that supports the cut strips  32  as they are fed by the infeed conveyor  34  to the butt splicer  36 . The racks  54 ,  60 ,  62 ,  68  are commercially available gear racks. 
     Each of the upper, upstream racks  54  is mounted to a lower end of a respective upper, nonpivotable, upstream jaw mounting bracket  75  that is mounted on a slide  76 . The slide  76  is slidably mounted on a linear guide  77  that is fixed to an upper pair of cross rails  78  of the frame  72 . Each of the upper, downstream racks  60  is mounted to a lower end of a respective upper, pivotable, downstream jaw mounting bracket  79 . Upper ends of each of the upper jaw mounting brackets  75 ,  79  are mechanically connected to a clamp drive comprised of a respective upper clamping actuator  82 , for example, a pneumatic cylinder, as shown in  FIG. 5 . The cylinders  82  are mounted to a truss  95  that is mounted on gearboxes  97  on the frame  72 . The gearboxes  97  are connected by a shaft  99  and operated by a handwheel  101 . Thus, turning the handwheel  101  permits the vertical position of the cylinders  82  and the upper pairs of racks  50  to be adjusted. The upper ends of each of the jaw mounting brackets  75 ,  79  are pivotally connected via a pivot pin  80  to a distal end of a cylinder rod  81  of a respective cylinder  82 . Simultaneous operation of the cylinders  82  in one state is operative to simultaneously move the upper jaw mounting brackets  75 ,  79  and respective pairs of upper racks  50  downward toward the pairs of lower racks  52 . Reversing the operation of the cylinders  82  is operative to move the upper racks  50  away from the lower racks  52 . 
     As shown in  FIG. 4 , the upper, downstream racks  60  are pivotable with respect to respective upper, upstream racks  54  by means of an engagement drive comprised of respective upper engagement actuators  83 , for example, a pneumatic cylinder. Specifically, the cylinders  83  are mounted on respective upper, downstream jaw mounting brackets  79 ; and as shown in  FIG. 3 , distal ends of respective cylinder rods  85  are connected to respective opposed, upper, upstream jaw mounting brackets  75 . Simultaneous operation of the engagement cylinders  83  in one state causes the upper, downstream jaw mounting brackets  79  and respective upper, downstream racks  60  to pivot toward the upper, upstream jaw mounting brackets  75  and the respective upper, upstream racks  54 , thereby engaging their respective teeth  58 ,  56 . Reversing the operation of the engagement cylinders  83  causes the upper, downstream racks  60  to move simultaneously away from the upper rear racks  54 , thereby disengaging their respective teeth  58 ,  56 . 
     Each of the lower, upstream racks  62  is mounted to a lower end of a respective lower, upstream, nonpivotable jaw mounting bracket  84  that is attached to a lower pair of cross rails  87  fixed to the frame  72 . Each of the lower, downstream racks  68  is mounted to a lower end of a respective lower, pivotable, downstream jaw mounting bracket  88 . Upper ends of each of the lower jaw mounting brackets  84 ,  88  are pivotally connected via a pivot pin  89 . The lower, downstream racks  68  are pivotable with respect to respective lower, upstream racks  62  by means of an engagement drive comprised of respective lower engagement actuators  90 , for example, a pneumatic cylinder. Specifically, the cylinders  90  are mounted on respective lower, downstream jaw mounting brackets  88 ; and as shown in  FIG. 3 , distal ends of respective cylinder rods  91  are connected to respective lower, upstream jaw mounting brackets  84 . Simultaneous operation of the engagement cylinders  90  in one state causes the lower, downstream jaw mounting brackets  88  and respective lower, downstream racks  68  to pivot toward the lower, upstream jaw mounting brackets  84  and the respective lower, upstream racks  62 , thereby engaging their respective teeth  66 ,  64 . Reversing the operation of the engagement cylinders  90  causes the lower, downstream racks  68  to move simultaneously away from the lower, upstream racks  62 , thereby disengaging their respective teeth  66 ,  64 . 
     Referring to  FIG. 6 , the operation of the floating table  70  and cylinders  90 ,  82 ,  83  are controlled by the operation of solenoids  94  that port pressurized air from a source  96  in a known manner. The operational states of the solenoids are commanded by output signals from a control  98 , for example, a programmable logic controller or other microcontroller. The operation of the control  98  is controlled by input devices, for example, a user I/O  100 , an edge sensor  102 , etc. The control  98  also provides output signals that command the operation of an infeed conveyor motor  104  ( FIG. 2 ) and an outfeed conveyor motor  106  that operate the respective infeed and outfeed conveyors  34 ,  108 . 
     The operation of the butt splicer  36  is controlled by various cycles of operation that are programmed in the control  98  in a known manner as a group of subroutines. For example, a first subroutine illustrated in  FIG. 7  is effective to position cut pieces  32  in the butt splicer  36  in preparation for making the butt joint. The process of  FIG. 5  starts with a preparation ply in the butt splicer  36  and a butt joint has just been completed. Referring to  FIGS. 1 ,  2 ,  6  and  7 , to position the preparation ply  38  and a new cut piece  32  for the next splice, the control  98  provides, at  502 , output signals to cause the infeed and outfeed conveyor motors  104 ,  106 , respectively, to run. At the same time, the control  98  provides an output signal to solenoid  94 d causing it to switch state and port pressurized air to the floating tables  70 . Thus, material can be moved over the butt splicer  36  with minimal friction from a subjacent support. Simultaneous operation of the infeed and outfeed conveyors  34 ,  108  causes the preparation ply strip  38  to move in a downstream direction  35  as viewed in  FIGS. 1 ,  2  and  8 . That motion of the preparation ply strip  38  results in a trailing edge  110  ( FIG. 8 ) passing beneath an edge sensor  102  mounted on the butt splicer  36 . Upon detecting the trailing edge  110 , the edge sensor  102  provides an output signal, at  504 , to the control  98 . 
     The control  98  then monitors the operation of the outfeed conveyor  108  to determine when the trailing edge  110  has been moved to a desired position with respect to the teeth  66  of the lower, downstream rack  68 . The distance between the point at which the trailing edge  110  is sensed by the edge sensor  102  and the final position of the trailing edge  110  on the lower, downstream rack  68  is a known value. Therefore, the operation of the outfeed conveyor motor  106  can be precisely controlled such that the outfeed conveyor  108  is stopped when the trailing edge  110  is at its desired position on the lower, downstream rack  68 . The desired position of the trailing edge varies depending on the design of the butt splicer  36 , the depth of the teeth of the racks, the nature of the preparation ply material, etc. The desired position of the trailing edge  110  is back from the front edges of the teeth  66  of the lower, downstream rack  68 . However, the desired amount of setback of the trailing edge  110  is determined experimentally in each application and may, for example, be a distance equal to somewhat less than half the length of the teeth  66 . 
     Detecting when the trailing edge  110  is in position may be accomplished in several ways. In one embodiment, the outfeed conveyor motor  106  has an encoder  112  attached thereto; and each output pulse from the encoder represents an incremental displacement of the outfeed conveyor  108 . Thus, the control  98  can detect and count output pulses from the encoder  112  and detect, at  506 , when the trailing edge  110  is at its desired position on the teeth  66  of the lower, downstream rack  68 . In an alternative embodiment, if the speed of the outfeed conveyor  108  is fixed, the control  98  can start an internal timer that counts the milliseconds required to move the trailing edge  110  from its position under the edge sensor  102  to a desired position on the teeth  66  of the lower, downstream rack  68 . In either event, when the control  98  determines, at  506 , that the trailing edge is at its desired position, it provides, at  508 , an output signal to the outfeed conveyor motor  106  commanding it to stop. In addition, the control  98  provides an output signal switching the state of solenoid  94   d  to remove the supply of pressurized air from the downstream floating table  70 , thereby providing a more rigid support for the cut piece  38 . 
     Simultaneously, with moving of the preparation ply  38 , the operation of the infeed conveyor  34  by the control  98  is also causing a new cut piece  32  to move in the downstream direction  35  toward the butt splicer  36 . After detecting the trailing edge  110  of the preparation ply  38 , the edge sensor  102  detects the leading edge  114  of the next cut piece  32  to be spliced to the preparation ply strip  38 ; and its output changes state at  510 . Upon the control  98  detecting that change of state, it starts counting pulses from an encoder  116  that is connected to the infeed conveyor motor  104 . By counting encoder pulses, the control  98  is able to determine when the leading edge  114  is at a desired position on the teeth  64  of the lower, upstream rack  62 . Again, the desired position of the leading edge  114  varies depending on the design of the butt splicer  36 , the depth of the teeth of the racks, the nature of the preparation ply material, etc. The desired position of the leading edge  114  is determined in the same way as described with respect to the desired position of the trailing edge  110 . Upon the control  98  detecting, at  512 , the desired position of the leading edge  114 , it provides, at  514 , an output signal to the infeed conveyor motor  104  commanding it to stop. It should be noted that the infeed conveyor  34  and outfeed conveyor  108  normally have about equal speeds, however, the outfeed conveyor may be run slightly faster than the infeed conveyor to increase the gap between the trailing edge  110  of the preparation ply  38  and the leading edge of the ply section  32  during conveyance. 
     In addition, the control  98  provides an output signal switching the state of solenoid  94   d  to remove the supply of pressurized air from the upstream floating table  70 , thereby providing a more rigid support for the cut piece  32 . At this point, the edges  110 ,  114  are at desired locations on respective teeth  66 ,  64  of the lower rear and forward racks  68 ,  62 , respectively. 
     After the edges are at the desired locations, the butt splicer is ready to form a butt splice joining the preparation ply strip  38  with the new cut piece  32 . Referring to  FIG. 9 , a process for making a butt splice begins with the control  98  providing, at  516 , an output signal to the solenoid  94   a  causing the solenoid to switch states and port pressurized air to the clamp cylinders  82 . The clamp cylinders simultaneously lower the plurality of upper racks  50  until the upper, downstream racks  60  contact a portion of the preparation ply strip  39  adjacent the trailing edge  110  being supported by respective lower, downstream racks  68 . At about the same time, the upper, upstream racks  54  contact a portion of the cut strip  32  adjacent the leading edge  114  being supported by the lower, upstream racks  62  as shown in  FIG. 8A . The time required to move the upper racks to their clamped position can be measured, and the control  98  can be programmed to initiate an internal timer equal to that clamping operation time. Therefore, when that timer expires, the control  98  then determines, at  518 , that the upper pairs of racks  50  have been moved to their respective desired clamped positions. 
     Thereafter, the control  98  then provides, at  520 , output signals to solenoids  94   b ,  94   c  to change the states of those solenoids and port pressurized air into the upper and lower engagement cylinders  83 ,  90 , respectively. The engagement cylinders  83 ,  90  are effective to move the upper and lower, downstream racks  60 ,  68  toward their mating upper and lower, upstream racks  54 ,  62 . The clamped upper and lower, downstream racks  60 ,  68  move the preparation ply  38  in an upstream direction  117  ( FIG. 8A ) to bring the preparation ply strip trailing edge  110  into contact with the cut piece leading edge  114  in an abutting relationship. Continued motion of the upper and lower, downstream racks  60 ,  68  firmly forces the preparation ply strip trailing edge  110  against the cut piece leading edge  114  to form the butt splice  40  ( FIG. 8B ). The tackiness of the elastomeric material helps to maintain the cut piece leading edge  114  in intimate contact with the preparation ply strip trailing edge  110 . That motion continues until the teeth  58 ,  66  of the respective upper and lower, downstream racks  60 ,  68  are fully engaged with the teeth  56 ,  64  of the respective upper and lower, upstream racks  54 ,  62  as shown in  FIG. 8B . 
     Once again, as previously described, the control  98  is able, by means of an internal timer, to determine, at  522 , that the upper and lower, downstream racks  60 ,  68  are fully engaged with respective upper and lower, upstream racks  54 ,  62 . At that point, the control  98  provides, at  524 , an output signal to switch the state of solenoid  94   a , thereby reversing the porting of pressurized air to the clamp cylinders  82 . The actuation of the clamp cylinders  82  causes the pairs of upper racks  50  to be raised and moved back to their unclamped position as shown in  FIG. 8C . Immediately thereafter, the control  98  provides, at  526 , output signals to the solenoids  94   b ,  94   c  to switch the states of the upper and lower engagement cylinders  83 ,  90 , thereby moving the upper and lower, downstream racks  60 ,  68  in the downstream direction  35  away from the upper and lower, upstream racks  54 ,  62 . That operation causes the racks to open to a position illustrated in  FIG. 8 . 
     In the above process, it should be noted that as the upper and lower, downstream racks  60 ,  68  move toward the respective upstream racks  54 ,  62 , the downstream racks  60 ,  68  and the preparation ply  38  move simultaneously. However, after the preparation ply trailing edge  110  contacts the cut piece leading edge  114 , the upper and lower, downstream racks  60 ,  68  have a relative motion with respect to the preparation ply strip  38  and therefore, must slide over the major surfaces of the preparation ply strip  38  without causing damage. To facilitate this, the sides  93  of the pivoting, downstream racks  60 ,  68  are coated with a “TEFLON” material. In addition, the teeth of the upper and lower, downstream racks  60 ,  68  are beveled at their leading edge of contact, that is, the surface  92  ( FIG. 4 ). The exact configuration of a beveled surface  92  is application dependent and varies with the nature of the ply material, the length of the racks, etc. In some applications, the beveled surface  92  has an angle of about 10° with respect to the side surface  93  of the rack; whereas, in other applications, the beveled surface has an angle of about 20°. The angle providing the best performance is determined experimentally by trial and error. Similarly, the desired length of the beveled surface  92  and its desired depth from the side surface  93  is also determined experimentally by trial and error. Such a beveled surface  92  facilitates a sliding motion of the downstream racks  60 ,  68  over the preparation ply strip  38  without gouging it or otherwise causing damage. 
     In operating the butt splicer  36 , it has been found that having a plurality of pairs of upper and lower racks  50 ,  52  provides a more consistent, higher quality butt splice than if the upper and lower racks  50 ,  52  extended continuously across a full width of the butt splicer  36 . The reliability and quality of the butt splice is further improved by nonrigidly mounting the upper racks  54 ,  60  to respective upper jaw mounting brackets  75 ,  79 . The nonrigid mountings of the racks  54 ,  60  are identical; and the mounting of rack  54  onto jaw mounting bracket  75  is shown in  FIG. 10 . Shoulder bolts  122  have shoulders that extend through slots  123  in the jaw mounting bracket  75  and threadedly engage the rack  54 . Thus, the rack  54  is not rigidly mounted to the respective jaw mounting bracket but is free to move relative thereto by an amount depending on the size of the slots  123 . Further, the end of the jaw mounting bracket  75  has a generally L-shaped notch  124  extending across a width of the jaw mounting bracket  75 . The slots  123  intersect a first notch surface  125  that contacts a rear surface of the rack  54 . A perpendicular surface  126  of the notch is curved, for example, with a  30  inch radius, to allow the rack  54  to rock thereon. It has been determined that such nonrigidly mounting of the upper racks  54 ,  60  to respective jaw mounting brackets  75 ,  79  substantially improves the quality of the butt splice  40 . 
     The operation of the butt splicer  36  is effective to provide reliable and high quality butt joints in the formation of a preparation ply strip. Further, it should be noted that the butt splicer  36  can be used to form butt splices that are substantially perpendicular to the infeed conveyor  34  as well as butt splices that are oblique with, or angled slightly from a perpendicular to the infeed conveyor  34 . Referring to  FIG. 3 , a forward leg  131  of the frame  72  of the butt splicer  36  is pivotally mounted to a base plate  132 . A rearward leg (not shown) of the frame  72  is supported by a caster  133  that rides on the base plate  132 . A ballscrew and nut assembly  134  is connected between the rearward leg and a handwheel  135 . Turning the handwheel  135  rotates the ballscrew and causes the nut that is pivotally attached to the rearward leg of the frame  72  to travel along the ball screw. As the nut is moved, the rearward leg of the frame  72  pivots with respect to the forward leg  131 , thereby skewing the rows of upper and lower racks  50 ,  52  with respect to a line perpendicular to a longitudinal centerline of the infeed conveyor  34 . An indicator associated with the handwheel  135  is calibrated in one degree increments. Permitting the frame  72  to be pivoted through an angle of up to about 10 degrees is sufficient for most applications. 
     It has been found that for preparation ply strips made with nonmetallic cords, the butt joint is stronger and more stable during the tire manufacturing process if it is covered with a gum strip. For the most efficient operation, the gum strip applier  44  operates simultaneously with the butt slicer  36 . Therefore, the gum strip applier  44  is positioned with respect to the butt splicer  36  such that, simultaneously with the preparation ply trailing edge being positioned at the butt splicer  36 , the most recently formed butt splice is positioned at a location at which a gum strip can be applied by the gum strip applier  44 . 
     Referring to  FIG. 11 , outfeed conveyor  108  is supported by a base  126 . The gum strip applier  44  has a frame  127  that is independently supported by a base  128  having legs  129 . Thus, the outfeed conveyor  108  and gum strip applier  44  are independently positionable with respect to the butt splicer  36 . The gum strip applier  44  is positioned such that when a butt splice is being formed on the butt splicer  36 , a previously made butt splice is located on outfeed conveyor  108  at a location  140  permitting the gum strip applier  44  to apply a gum strip to the previously made butt splice. Referring to  FIG. 12 , the gum strip applier  44  has a gum strip conveyor  142  and a vacuum head assembly  144 . The vacuum head assembly  144  has two degrees of freedom that permit it to remove a gum strip from the conveyor  142  and place it on a butt splice positioned at the upstream location  140 . 
     Referring to  FIG. 13 , an X-axis, horizontal drive motor  146  is mechanically connected to one end of a ball screw  148 ; and a sprocket  150  is mounted on an opposite end of the ball screw  148  and operatively engages a timing belt  152 . The timing belt  152  is further connected to a second sprocket  154  mounted on an end of a second ball screw  156 . The ball screws  148 ,  156  have respective ball nuts  158 ,  160  that support and carry a carriage  162  that is supported and guided in its linear motion by linear bearings  163 . As shown in  FIG. 13 , the carriage  162  supports the vacuum head assembly  144 . The vacuum head assembly  144  has a length substantially equal to the length of the butt splice, that is, the full width of the preparation ply strip. Rotation of the horizontal drive motor  146  is operative to simultaneously move the ball nuts  158 ,  160  ( FIG. 13 ), the carriage  162  and the vacuum head assembly  144  in a horizontal direction substantially parallel to a longitudinal axis of the preparation ply strip. 
     Referring to  FIG. 14 , a Z-axis vertical drive motor  164  is mounted on, and supported by, the carriage  162  and is mechanically connected to one end of a first ball screw  166 . A first timing sprocket  168  is mounted on an opposite end of the first ball screw  166  and operatively engages a timing belt  170  that also engages a sprocket  172  mounted on an end of a second ball screw  174 . First and second ball nuts  176 ,  178  are rotatably mounted on the respective ball screws  166 ,  178  and are connected to a vacuum head plenum  180 , which is guided in its linear motion by linear bearings  181 . 
     Referring to  FIG. 12 , a vacuum head  182  is supported by vertical posts  184  that are fixed to the plenum  180 . Biasing components, for example, compression springs  181 , are mounted on the posts  184  between the vacuum head  182  and the plenum  180 . The vacuum head  182  has a length that extends across substantially the whole width of the outfeed conveyor as well as the length of a butt splice in the preparation ply strip. Thus, operation of the vertical drive motor  164  causes the vacuum plenum  180  and vacuum head  182  to raise and lower with respect to the outfeed conveyor  108 . 
     Referring to  FIG. 6B , the control  98  provides output signals to the strip conveyor motor  186  and receives input pulses from a strip conveyor encoder  188  by which the control  98  can determine the linear motion of the strip conveyor  142 . Similarly, in response to output signals commanding the operation of the horizontal and vertical drive motors  146 ,  164 , the control  98  receives feedback signals from the encoders  190 ,  192  representing motion of the vacuum head  182 . The control  98  is also operatively connected to a vacuum pump  194  that applies the partial vacuum pressure to the vacuum head plenum  180 . A vacuum is applied and released from the vacuum head  182  by means of a vacuum release valve  196  connected between the vacuum head plenum and the vacuum head  182 . When in its first state, the valve  196  closes the vacuum head to atmosphere and opens it to the vacuum head plenum  180 , thereby applying a partial vacuum to the vacuum head  182 . In its opposite state, the valve  196  closes the connection between the vacuum head  182  and the vacuum head plenum  180  and opens the vacuum head  182  to atmosphere, thereby dissipating the partial vacuum therein. The control  98  is also connected to a solenoid  94   e  that is operative to change the state of a knife cylinder  198 , thereby operating a knife  200  on the gum strip preparation equipment  48  ( FIG. 2 ) for cutting the gum strips to desired lengths. 
     There are three independent but coordinated operations or subroutines that are executed by the gum strip applier  44 . Referring to  FIG. 12 , first, a gum strip  42  is moved by the conveyor  142  to a location ready for transfer to the vacuum head  182 . A second operation is for the vacuum head  182  to pick up the gum strip from the conveyor  142  and be ready to apply the gum strip to the butt joint. A third operation is to apply the gum strip to the butt joint after the butt joint has been moved to the desired location  140  ( FIG. 11 ). Referring to  FIGS. 6B ,  12  and  15 , to cut a gum strip to length, the control  98  provides, at  552 , an output signal to operate the strip conveyor motor  186 , thereby causing the strip conveyor  142  to feed the gum strip. As the gum strip  42  is fed, the control  98  monitors and counts output pulses from the strip conveyor encoder  188 . When the control  98  counts, at  554 , a number of pulses equal to the desired length of the gum strip, the control  98  provides, at  556 , an output signal commanding the strip conveyor motor  186  to stop. Thereafter, the control  98  provides, at  558 , an output signal commanding the solenoid  94 e to change state, thereby porting pressurized fluid to the knife cylinder  198  and operating the knife  200 . Immediately thereafter, the output signal from the control  98  changes state, thereby reversing the state of solenoid  94   e  and returning the knife cylinder  198  to its original position. That operation of actuating the knife cylinder reciprocates the knife  200  and establishes a cut end of the gum strip  145 . This action provides a gum strip on the strip conveyor  142  that is of the desired length, that is, the length of the butt strip  40 . 
     Thereafter, the control  98  provides, at  560 , an output signal commanding the strip conveyor motor  186  to start; and the strip conveyor  142  transports the gum strip  42  across the width of the outfeed conveyor  108 . Again, the control  98  is monitoring and counting output pulses from the strip conveyor encoder  188  and is able to determine when the cut gum strip is in its desired position. When that position is detected, at  562 , the control  98  provides, at  564 , an output signal commanding the strip conveyor motor  186  to stop. At this point, a gum strip  42  of the desired length is located on the strip conveyor  142  at a location ready to be picked up by the vacuum head  182 . 
     Referring to  FIGS. 6B ,  11  and  16 , to pick up the gum strip from the gum strip conveyor  142 , assume that the vacuum head  182  is elevated and the carriage  162  is positioned to locate the vacuum head  182  at a downstream location above the gum strip conveyor  142 , ready to pick up a gum strip. The control  98  provides, at  565 , an output signal to the vacuum release valve  196  closing the vacuum head  182  to atmosphere and opening the vacuum head to the vacuum head plenum  180 . A vacuum is then applied to the vacuum head  182 . The control  98  also provides, at  565 , output signals to the Z-axis, vertical drive motor  164 , thereby rotating the ball screws  166 ,  174  in a direction to move the vacuum head  182  vertically downward toward the gum strip conveyor  142 . The control monitors and counts output pulses from the vertical drive encoder  192  and detects, at  566 , when the vacuum head  182  is at its desired position immediately above the strip conveyor  142 . At that position, the vacuum head  182  is sufficiently close to the strip conveyor  142  that the vacuum head  182  is able to lift the gum strip off of the gum strip conveyor  142 . 
     The control  98  then provides, at  567 , output signals to the Z-axis vertical drive motor  164  and the X-axis horizontal drive motor  146  causing the vacuum head to move to a ready position immediately above the location  140  at which the butt joint is located. As will be appreciated, the control  98  can be programmed to first operate the vertical drive motor  164  to raise the vacuum head  182  and thereafter, operate the horizontal drive motor  146  to move the vacuum head horizontally to a ready position over the butt joint location  140 . Alternatively, in other applications, the motors  146  and  164  can be operated simultaneously to move the vacuum head  182  to the ready position. In either embodiment, the control signal monitors output pulses from the encoders  190 ,  192  in a manner previously described to detect, at  568 , that the vacuum head  182  is at the ready position. Thereafter, the control  98  provides, at  569 , output signals to the either or both of the motors  146 ,  164  commanding them to stop the vacuum head  182  at the ready position. 
     Referring to  FIGS. 6B ,  11 ,  12  and  17 , to apply the gum strip to the butt joint, assume that a butt joint has been moved to the location  140  beneath the vacuum head  182  at the ready position. The control  98  provides, at  572 , output signals to the Z-axis, vertical drive motor  166  rotating ball screws  166 ,  174  in a direction causing the vacuum head  182  to lower onto and contact the preparation ply strip  38 . The gum strip has a length that extends over substantially the whole length of the butt splice. Further, the gum strip has a width such that it extends across the butt splice and over a portion of the major surfaces on both sides of the butt splice  40 . The vacuum head  182  is resiliently and movably mounted with respect to the vacuum head plenum  180 . Therefore, as the vertical drive motor  164  continues to move the vacuum head plenum  182  downward, the vacuum head  182  contacts the preparation ply strip  38  and the springs  181  apply a desired, downward biasing force against the vacuum head  182 , thereby applying a desired application force against the gum strip  42 . That force is determined by spring constants of springs  181  and is effective to cause the adhesive on the gum strip  42  to better adhere to the preparation ply strip  38 . 
     Again, the control  98  is monitoring the output pulses from the encoder  190  and detects, at  573 , when the vacuum head  182  has been moved to its lowermost position. Thereafter, the control  98  provides, at  574 , an output signal to the vertical drive motor  164  commanding it to stop. In addition, the control  98  provides an output signal to the vacuum release valve  196  changing the state of the valve such that the fluid connection between the vacuum head plenum and the vacuum head  182  is blocked, and the vacuum head  182  is open to atmosphere. At this point, the control  98  may allow the vacuum head  182  to dwell at its lowermost position to allow the adhesive on the gum strip to set. Such a dwell time is determined by an internal timer in the control  98  and can be set from zero to any desired number of seconds in a known manner. 
     Thereafter, the control  98  provides, at  575 , output signals commanding the drive motor  146 ,  162  to move the vacuum head back to the pickup position above the gum strip conveyor  142 . In a manner as previously described, the control monitors the encoders  190 ,  192  to detect, at  576 , when the vacuum head  182  is at the pickup position; and thereafter, at  577 , the control  98  provides output signals to stop the drive motors  146 ,  164 . 
     As indicated earlier, it is desirable that the gum strip applier  44  operate simultaneously with the butt splicer  36  to apply the gum strip  42  over the most recently formed butt splice while the butt splicer  36  is splicing the next cut piece  32  to the preparation ply strip  38 . Therefore, prior to a splice being moved to the position  140 , the gum strip applier  44  is operated to prepare a gum strip for application. From the above, it is clear that for a more efficient operation, several of the above processes and subroutines can be operating simultaneously. For example, while a butt splice is being made ( FIG. 9 ) and a gum strip is being applied over a previously made butt splice ( FIG. 17 ), a gum strip can be cut to size and moved into the gum strip applier ( FIGS. 15 and 16 ).  FIG. 18  is a state diagram of a program in the control  98  that permits several operations or subroutines to be operated simultaneously. 
     If at  580 , there is no gum strip on the gum strip conveyor  142 , the control  98  executes, at  581 , the subroutine of  FIG. 15  to cut a gum strip to length. If a gum strip is on the conveyor  142 , the control  98  determines, at  582 , whether the vacuum head is empty; and if so, executes, at  583 , the subroutine of  FIG. 16  to pick up a gum strip from the conveyor  142 . If the vacuum head  182  is holding a gum strip, the control, at  584 , determines whether a butt splice is in position and ready to be made. If so, the control, at  585 ,  586 , proceeds to make a butt splice by executing the butt splice subroutine of  FIG. 9  and simultaneously apply gum strip to a previously made butt splice by executing the subroutine of  FIG. 17 . If the control  98 , at any time, detects, at  584 , that a butt splice is not in position ready to be made, it brings a new cut piece  32  into the butt splicer  36  by executing the position preparation ply subroutine of  FIG. 7 . The above process provides an economical, efficient and reliable butt splice of preparation plies, thereby providing a higher quality tire manufacturing process. 
     It should be noted that the location of the gum strip applier  44  can be adjusted with respect to the butt splicer  36  to accommodate different widths of calendered material being supplied to the infeed conveyor  34 . Referring to  FIG. 12 , each side of the gum strip applier frame  127  has grooved rollers  136  that are mounted on opposite sides of a linear guide  137  attached to the base  128 . As shown in  FIG. 11 , a ballscrew and nut assembly  138  is mounted to the base  128 . A handwheel  139  is operatively connected to the ballscrew nut and is rotatably mounted to the frame  127 . Rotation of the handwheel  139  rotates the ballscrew nut causing it to move the frame  127  and the components supported thereby with respect to the base  128  and the butt splicer  36 . Thus, calendered material of different widths can be readily accommodated. It should be noted that when the location of the frame  127  and gum strip conveyor  142  is changed, the feeding of the gum strip  42  from the preparation equipment  48  ( FIG. 2 ) must also be adjusted in a known manner, for example, by moving the location of the equipment  48 . 
     While the present invention has been illustrated by a description of various embodiments and while these embodiments have been described in considerable detail, it is not the intention of Applicants to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications will readily appear to those skilled in the art. For example, in the described embodiment, the engagement actuators  85 ,  90  and clamping actuator  82  are described as being pneumatic cylinders; as will be appreciated, in alternative embodiments, those actuators may be hydraulic actuators or electromechanical drive systems. 
     In the described embodiment, individual clamping cylinders  82  are used for each upper pair of racks  50 ; however, in an alternative embodiment, all of the pivotable jaw mounting brackets  79 ,  88  can be mechanically connected to a common drive link that is operated by only one or two actuators. In another alternative embodiment, all of the upper, pivotable jaw mounting brackets  79  can be mechanically connected to a common drive link that is operated by only one or two actuators; and all of the lower, pivotable jaw mounting brackets  88  can be mechanically connected to another common drive link that is operated by only one or two actuators. In the described embodiment, the upper pairs of racks are movable vertically and the lower pairs of racks  52  are fixed in elevation. In alternative embodiments, that arrangement can be reversed with the upper pairs of racks being fixed and the lower pairs of racks being movable. 
     Further, in the described embodiment, the upper and lower pairs of racks are mounted on the downstream side of the frame  72 . Thus, the pivoting racks  60 , 68  are located downstream of the nonpivoting racks  54 ,  62 ; however, in an alternative embodiment, the upper and lower pairs of racks  50 ,  52  can be mounted on the opposite, upstream side of the frame  72 . In that embodiment, the pivoting racks  60 ,  68  are located upstream of the nonpivoting racks  54 ,  62 ; and the nonpivoting racks  54 ,  62  hold the preparation ply  38 , while the pivoting racks  60 ,  68  pull the cut piece  32  toward the preparation ply  38  to form the butt splice. 
     In the described embodiment, the control  98  is depicted as a single unit; however, as will be appreciated, the control  98  can be comprised of several different control units that are in electrical communications with each other. Further, such different control units are often in different locations. For example, one control unit may be placed with the butt splicer  36 , another with the gum strip applier  44  and a third with the preparation equipment  48 . 
     Therefore, the invention in its broadest aspects is not limited to the specific details shown and described. Consequently, departures may be made from the details described herein without departing from the spirit and scope of the claims which follow.