Patent Publication Number: US-2021162695-A1

Title: Tire carcass ply joining apparatus and method

Description:
FIELD OF THE INVENTION 
     The present invention relates generally to an apparatus and method for producing a continuous preparation ply material for making pneumatic tires and, more particularly, to an apparatus and method for making a continuous carcass ply from multiple pieces. 
     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 non-uniform 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. 
     SUMMARY OF THE INVENTION 
     A first method in accordance with the present invention forms a butt joint between ends of first and second plies and splices the first and second plies together. The first method includes the steps of: positioning a first splice edge of a first ply at a first location; positioning a second splice edge of a second ply at a second location; wrapping a gum strip around the first splice edge such that the gum strip forms a U-shaped structure in section that allows the gum strip to extend from a first planar side of the first ply over the first splice edge to a second opposite planar side of the first ply; not wrapping a second gum strip around the second splice edge; placing the first splice edge in abutting relationship to the second splice edge; stitching the first splice edge to the second splice edge such that stitches each extend from the first planar side of the first ply, through the gum strip, to a first planar side of the second ply; and curing the first splice edge to the second splice edge. 
     According to another aspect of the first method, the first and second plies both have parallel wire cords spaced a predetermined distance apart. 
     According to still another aspect of the first method, the gum strip has a nominal thickness equal the predetermined distance of the first and second plies. Because gum strip thickness may vary plus or minus 35% to 65%, the predetermined distance for the butt splice may vary correspondingly plus or minus 70% to 130%. 
     According to yet another aspect of the first method, each stitch extends from the gum strip to the second ply. 
     According to still another aspect of the first method, the gum strip is constructed of a material at least 20% softer than a substrate material of the first and second plies. 
     A second method forms a continuous material ply of the type used to make vehicle tires with the continuous material ply being made by joining multiple plies. The second method includes the steps of: positioning a first splice edge of a first ply at a first location; positioning a second splice edge of a second ply at a second location; wrapping a gum strip around the first splice edge such that the gum strip forms a U-shaped structure in section that allows the gum strip to extend from a first planar side of the first ply over the first splice edge to a second opposite planar side of the first ply; not wrapping a gum strip around the second splice edge; placing the first splice edge in abutting relationship to the second splice edge at a third location; stitching the first splice edge to the second splice edge such that stitches each extend from the first planar side of the first ply, through the gum strip, to a first planar side of the second ply; and curing the first splice edge to the second splice edge. 
     According to another aspect of the second method, the second method further includes the steps of: providing pairs of upper racks having teeth and extending end-to-end having first upper racks movable with respect to second upper racks; providing pairs of lower racks having teeth and extending end-to-end adjacent the pairs of upper racks, the pairs of lower racks having first lower racks movable with respect to second lower racks; positioning the first edge of the first over teeth of the first lower racks; positioning the second edge of the second ply over teeth of the second lower racks; and clamping the first and second plies between the pairs of upper racks and the pairs of lower racks; simultaneously engaging teeth of all first upper racks with teeth of all second upper racks; and teeth of all first lower racks with teeth of all second lower racks to firmly press the first edge of the first ply against the second edge of the second ply to splice the first and second plies together. 
     According to still another aspect of the second method, the gum strip is constructed of a material at least 20% softer than a substrate material of the first and second plies. 
     A system in accordance with the present invention forms a continuous material ply of the type used to make vehicle tires with the continuous material ply being made by joining multiple plies. The system includes: positioning a first splice edge of a first ply at a first location; positioning a second splice edge of a second ply at a second location; wrapping a gum strip around the first splice edge such that the gum strip forms a U-shaped structure in section that allows the gum strip to extend from a first planar side of the first ply over the first splice edge to a second opposite planar side of the first ply; not wrapping a gum strip around the second splice edge; placing the first splice edge in abutting relationship to the second splice edge at a third location; stitching the first splice edge to the second splice edge such that stitches each extend from the first planar side of the first ply, through the gum strip, to a first planar side of the second ply; and curing the first splice edge to the second splice edge. 
     According to another aspect of the system, an apparatus applies a gum strip at a butt joint thereby splicing the first edge to the second edge. The apparatus may include a conveyor for providing gum strips having a desired length and thickness; and a transfer device for automatically removing the gum strips from the conveyor and placing the gum strip at the butt joint. 
     According to still another aspect of the system, the transfer device comprises a vacuum head. 
     According to yet another aspect of the system, the vacuum head is resiliently mounted to the transfer device to provide a force against the gum strip upon the gum strip being placed at the butt joint. 
     According to still another aspect of the system, a cutting apparatus automatically cuts the gum strip to the desired length. 
     According to yet another aspect of the system, a controller is operatively connected to the conveyor and the transfer device to operate the conveyor and the transfer device. 
     According to still another aspect of the system, the gum strip is constructed of a material at least 20% softer than a substrate material of the first and second plies. 
     An apparatus for use with the present invention 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 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 apparatus forms 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. 
     The apparatus 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 apparatus has 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. 
     A third method for use with the present invention positions 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. The third method applies a gum strip only over a butt joint splicing end of first preparation ply by providing a gum strip having a desired length and then, automatically placing the gum strip on the 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. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention will be described by way of example and with reference to the accompanying drawings, in which: 
         FIG. 1  schematically shows two ply segments placed adjacent each other. 
         FIG. 2  schematically shows one edge of one of the ply segments prepared for joining. 
         FIG. 3  schematically shows a butt splice in accordance with the present invention. 
         FIG. 4  is a schematic illustration of a cord preparation ply manufacturing line having a butt splicer and gum strip applier for use with the present invention. 
         FIG. 5  is a side view of the butt splicer and the gum strip applier of  FIG. 4 . 
         FIG. 6  is a side view of the butt splicer of  FIG. 5 . 
         FIG. 7  is a partial perspective view of a portion of the butt splicer of  FIG. 5  that illustrates the plurality of pairs of upper and lower racks. 
         FIG. 8  is an end view of the butt splicer of  FIG. 5 . 
         FIG. 9  is a schematic block diagram of part of a control system used to control the operation of the butt splicer and gum strip applier of  FIG. 4 . 
         FIG. 10  is a schematic block diagram of another part of a control system used to control the operation of the butt splicer and gum strip applier of  FIG. 4 . 
         FIG. 11  is a flowchart of a subroutine implemented by the control system of  FIG. 9  for positioning a preparation ply piece prior to a butt splicing cycle. 
         FIG. 12  is an end view illustrating a first condition of a rack on the butt splicer of  FIG. 4  in executing the butt splicing cycle of  FIG. 9 . 
         FIG. 13  is an end view illustrating a second condition of a rack on the butt splicer of  FIG. 4  in executing the butt splicing cycle of  FIG. 9 . 
         FIG. 14  is an end view illustrating a third condition of a rack on the butt splicer of  FIG. 4  in executing the butt splicing cycle of  FIG. 9 . 
         FIG. 15  is an end view illustrating a fourth condition of a rack on the butt splicer of  FIG. 4  in executing the butt splicing cycle of  FIG. 9 . 
         FIG. 16  is a flowchart of a subroutine implemented by the control system of  FIG. 9  for butt splicing the preparation ply materials. 
         FIG. 17  illustrates how the upper pairs of racks are non-rigidly mounted in jaw mounting brackets on the butt splicer of  FIG. 5 . 
         FIG. 18  is an end view of the gum applier of  FIG. 5 . 
         FIG. 19  is a side view of the gum applier of  FIG. 5 . 
         FIG. 20  is a partial top view of the gum applier of  FIG. 5  illustrating horizontal drive components. 
         FIG. 21  is a partial end view of the gum applier of  FIG. 5  illustrating vertical drive components. 
         FIG. 22  is a flowchart of a subroutine implemented by the control system of  FIG. 9  for cutting a gum strip to length. 
         FIG. 23  is a flowchart of a subroutine implemented by the control system of  FIG. 9  for picking up a gum strip with a vacuum head. 
         FIG. 24  is a flowchart of another subroutine implemented by the control system of  FIG. 9  for applying a gum strip with a vacuum head. 
         FIG. 25  is a state diagram illustrating the operation of the control system of  FIG. 9  for simultaneously operating the butt splicer and gum strip applier of  FIG. 5 . 
     
    
    
     DETAILED DESCRIPTION OF EXAMPLES OF THE PRESENT INVENTION 
     Referring to  FIG. 4 , in a preparation ply manufacturing line  20 , a strip of calendered material  22  may be fed from calender rolls (not shown) in a known manner. The calendered material  22  may be 0.040 inch to 0.060 inch thick and have cords  24  made from a metallic or nonmetallic material extending longitudinally generally parallel to the calendered edges  26 . Non-metallic cords  24  may be less rigid than metallic cords resulting in the calendered edges  26  being nonlinear and undulating. The calendered material may be fed by a conveyor  28  past a cutter  30 , which cuts the calendered material  22  to desired lengths, depending on the application. The resulting rectangular pieces  32  may then be transferred onto a transverse infeed conveyor  34 . The pieces may then be 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  may be 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 may be collected on windup rolls  43  in a known manner. The continuous preparation ply strip  38  may have 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  (e.g., from right to left as viewed in  FIG. 4 ). The term “upstream” is used to designate a motion in an opposite direction. Components of 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. 5  is a side view of a portion of the preparation ply manufacturing line  20  and a strip of calendered material  22  that includes the infeed conveyor  34 , the butt splicer  36 , and the gum strip applier  44 . Preparation equipment  48  for the gum strip applier  44  may feed the gum strip from a roll and separate and wind up a covering over the gum strip adhesive. 
     Referring to  FIGS. 7 and 8 , the butt splicing machine  36 , or butt splicer, may have a frame  72  that supports floating tables  70  on both the upstream and downstream sides of the butt splicing machine. Pairs of upper racks  50  and pairs of lower racks  52  may be mounted to extend transversely across the width of the butt splicing machine  36 . Each pair of upper racks  50  may comprise a nonpivotable upstream rack  54  having teeth  56  engageable with teeth  58  of a pivotable downstream rack  60 . Similarly, each pair of lower racks  52  may comprise a nonpivotable upstream rack  62  having teeth  64  engageable with teeth  66  of a pivotable downstream rack  68 . The pairs of lower racks  52  may be fixed in elevation immediately adjacent the table  70  that supports the cut strips  32  being fed by the infeed conveyor  34  to the butt splicer  36 . 
     Each of the upper upstream racks  54  may be mounted to a lower end of a respective upper nonpivotable upstream jaw mounting bracket  75  mounted on a slide  76 . The slide  76  may be slidably mounted on a linear guide  77  fixed to an upper pair of cross rails  78  of the frame  72 . Each of the upper downstream racks  60  may be 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  may be mechanically connected to a clamp drive comprised of a respective upper clamping actuator  82  (e.g., a pneumatic cylinder as shown in  FIG. 8 ). The cylinders  82  may be re mounted to a truss  95  mounted on gearboxes  97  on the frame  72 . 
     The gearboxes  97  may be connected by a shaft  99  and operated by a handwheel  101 . Thus, turning the handwheel  101  may adjust the vertical position of the cylinders  82  and the upper pairs of racks  50 . The upper ends of each of the jaw mounting brackets  75 ,  79  may be 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  may 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  may move the upper racks  50  away from the lower racks  52 . 
     As shown in  FIG. 7 , the upper downstream racks  60  may be pivotable with respect to respective upper upstream racks  54  by means of an engagement drive comprised of respective upper engagement actuators  83  (e.g., a pneumatic cylinder). Specifically, the cylinders  83  may be mounted on respective upper downstream jaw mounting brackets  79 ; and, as shown in  FIG. 6 , distal ends of respective cylinder rods  85  may be connected to respective opposed upper upstream jaw mounting brackets  75 . Simultaneous operation of the engagement actuators  83  may cause 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  may cause 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  may be mounted to a lower end of a respective lower upstream nonpivotable jaw mounting bracket  84  attached to a lower pair of cross rails  87  fixed to the frame  72 . Each of the lower downstream racks  68  may be 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  may be pivotally connected via a pivot pin  89 . The lower downstream racks  68  may be pivotable with respect to respective lower upstream racks  62  by means of an engagement drive comprised of respective lower engagement actuators  90  (e.g., pneumatic cylinders). Specifically, the actuators  90  may be mounted on respective lower downstream jaw mounting brackets  88 ; and, as shown in  FIG. 6 , distal ends of respective cylinder rods  91  may be connected to respective lower upstream jaw mounting brackets  84 . Simultaneous operation of the engagement actuators  90  may cause 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 actuators  90  may cause 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. 9 , the operation of the floating table  70  and cylinders  90 ,  82 ,  83  may be controlled by the operation of solenoids  94  transferring pressurized air from a source  96 . The operational states of the solenoids may be commanded by output signals from a controller  98  (e.g., a programmable logic controller, microcontroller, etc.). The operation of the controller  98  may be controlled by input devices (e.g., a user  1 / 0   1   00 , an edge sensor  102 , etc.) The controller  98  may also provide 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  may be controlled by various cycles of operation programmed into the controller  98  as a group of subroutines. For example, a first subroutine ( FIG. 7 ) may position cut pieces  32  in the butt splicer  36  in preparation for making the butt joint. The process of  FIG. 5  may start with a preparation ply  38  in the butt splicer  36  and a completed butt joint. 
     Referring to  FIGS. 4, 5, 9, and 11 , to position the preparation ply  38  and a new cut piece  32  for the next splice, the controller  98  may provide, at  502 , output signals to run the infeed and outfeed conveyor motors  104 ,  106 , respectively. Simultaneously, the controller  98  may provide an output signal to the solenoid  94  for adjusting state and transferring pressurized air to the floating tables  70 . Thus, material may be moved over the butt splicer  36  with minimal friction from a subjacent support. Simultaneous operation of the infeed and outfeed conveyors  34 ,  108  may move the preparation ply strip  38  in a downstream direction  35 , as viewed in  FIGS. 4, 5, and 12 . The motion of the preparation ply strip  38  may result in a trailing edge  110  ( FIG. 12 ) passing beneath an edge sensor  102  mounted on the butt splicer  36 . Upon detecting the trailing edge  110 , the edge sensor  102  may provide an output signal, at  504 , to the controller  98 . 
     The controller  98  may monitor 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  may be a known value. Therefore, the operation of the outfeed conveyor motor  106  may be precisely controlled such that the outfeed conveyor  108  stops when the trailing edge  110  is at its desired location on the lower downstream rack  68 . The desired location of the trailing edge  110  may vary depending on the design of the butt splicer  36 , the depth of the teeth of the racks, the nature of the preparation ply material  38 , etc. 
     The desired position of the trailing edge  110  may be set back from the front edges of the teeth  66  of the lower downstream rack  68 . However, the amount of setback of the trailing edge  110  may be 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, the outfeed conveyor motor  106  may have an encoder  112  attached thereto with each output pulse from the encoder representing an incremental displacement of the outfeed conveyor  108 . Thus, the controller  98  may 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 another, if the speed of the outfeed conveyor  108  is fixed, the controller  98  may start an internal timer that counts 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 . When the controller  98  determines, at  506 , that the trailing edge  110  is at its desired position, the controller may provide, at  508 , an “STOP” output signal to the outfeed conveyor motor  106 . In addition, the controller  98  may provide an output signal switching the state of solenoid  94  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 controller  98  may also cause 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  may detect the leading edge  114  of the next cut piece  32  to be spliced to the preparation ply strip  38  with its output changing state, at  510 . Upon detecting a change of state, the controller  98  may begin counting pulses from an encoder  116  connected to the infeed conveyor motor  104 . By counting encoder pulses, the controller  98  may 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  may vary depending on 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  may be determined in the same way as described above with respect to the desired position of the trailing edge  110 . 
     Upon detecting, at  512 , the desired position of the leading edge  114 , the controller  98  may provide, at  514 , an “STOP” output signal to the infeed conveyor motor  104 . The infeed conveyor  34  and the outfeed conveyor  108  may normally have about equal speeds or the outfeed conveyor may 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  114  of the ply section  32 . 
     The controller  98  may also provide an output signal switching the state of solenoid  94  for removing the supply of pressurized air from the upstream floating table  70  and for providing a more rigid support for the cut piece  32 . At this point, the edges  110 ,  114  may be located at desired locations on respective teeth  66 ,  64  of the lower rear and forward racks  68 ,  62 . 
     After the edges  110 ,  114  are at the desired locations, the butt splicer  36  may form a butt splice joining the preparation ply strip  38  with the new cut piece  32 . Referring to  FIG. 16 , a process for making a butt splice may begin with the controller  98  providing, at  516 , an output signal to the solenoid  94  causing the solenoid to switch states and port pressurized air to the clamp cylinders  82 . The clamp cylinders  82  may 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 . 
     Simultaneously, the upper upstream racks  54  may contact a portion of the cut strip  32  adjacent the leading edge  114  supported by the lower upstream racks  62 , as shown in  FIG. 13 . The time required to move the upper racks  54  to their clamped position may be measured and the controller  98  may initiate an internal timer equal to that clamping operation time. Therefore, when that time expires, the controller  98  may then determine, at  518 , the upper pairs of racks  50  have been moved to their respective clamped positions. 
     Thereafter, the controller  98  may then provide, at  520 , output signals to the solenoids  94   b ,  94   c  changing the states of those solenoids and porting pressurized air into the upper and lower engagement cylinders  83 ,  90 , respectively. The engagement cylinders  83 ,  90  may move the upper and lower downstream racks  60 ,  68  toward their corresponding mating upper and lower upstream racks  54 ,  62 . The clamped upper and lower downstream racks  60 ,  68  may move the preparation ply  38  in an upstream direction  117  ( FIG. 13 ) 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  may firmly force the preparation ply strip trailing edge  110  against the cut piece leading edge  114  to form the butt splice  40  ( FIG. 14 ). The tackiness of the elastomeric material may maintain the cut piece leading edge  114  in contact with the preparation ply strip trailing edge  110 . That motion may continue 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. 14 . 
     As previously described, the controller  98  may determine, at  522 , the upper and lower downstream racks  60 ,  68  are fully engaged with respective upper and lower upstream racks  54 ,  62 . The controller  98  may then provide, 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  may cause the pairs of upper racks  50  raise and move back to an undamped position, as shown in  FIG. 15 . Immediately thereafter, the controller  98  may provide, 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 . This operation may cause the racks to open to the position illustrated in  FIG. 12 . 
     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  may 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  may 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. The sides  93  of the pivoting downstream racks  60 ,  68  may be coated with a polytetrafluoride (PTFE) material. In addition, the teeth of the upper and lower downstream racks  60 ,  68  may be beveled at their leading edges of contact, that is, the surface  92  ( FIG. 7 ). The configuration of the beveled surface  92  may be application dependent and vary with the nature of the ply material, the length of the racks, etc. The beveled surface  92  may have an angle of about 10° with respect to the side surface  93  of the rack or an angle of about 20°. An angle providing optimum performance may be determined experimentally. Similarly, the desired length of the beveled surface  92  and the desired depth from the side surface  93  may also be determined experimentally. Such a beveled surface  92  may facilitate sliding motion of the downstream racks  60 ,  68  over the preparation ply strip  38  without gouging or otherwise causing damage. 
     The butt splicer  36  may have a plurality of pairs of upper and lower racks  50 ,  52  for a more consistent, higher quality butt splice than if the upper and lower racks  50 ,  52  extend continuously across a full width of the butt splicer  36 . Reliability and quality of the butt splice may be further improved by nonrigidly mounting the upper racks  54 ,  60  to respective upper jaw mounting brackets  75 ,  79 . The nonrigid mounting of the racks  54 ,  60  may be identical; and the mounting of rack  54  onto a jaw mounting bracket  75  is shown in  FIG. 17 . Shoulder bolts  122  may extend through slots  123  in the jaw mounting bracket  75  and threadedly engage the rack  54 . Thus, the rack  54  may be nonrigidly mounted to the respective jaw mounting bracket  75 , but also be 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  may have a generally L-shaped notch  124  extending across a width of the jaw mounting bracket  75 . The slots  123  may intersect a first notch surface  125  that contacts a rear surface of the rack  54 . A perpendicular surface  126  of the notch  124  may be curved (e.g., a 30 inch radius) to allow the rack  54  to rock thereon. Such nonrigid mounting of the upper racks  54 ,  60  to respective jaw mounting brackets  75 ,  79  may substantially improve the quality of the butt splice  40 . 
     The operation of the butt splicer  36  may provide reliable and high quality butt joints in the formation of a preparation ply strip. Further, the butt splicer  36  may 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 line perpendicular to the infeed conveyor. Referring to  FIG. 6 , a forward leg  131  of the frame  72  of the butt splicer  36  may be pivotally mounted to a base plate  132 . A rearward leg (not shown) of the frame  72  may be supported by a caster  133  that rides on the base plate  132 . A ball screw and nut assembly  134  may connect the rearward leg and a handwheel  135 . Turning the handwheel  135  may rotate the ball screw and cause the nut, pivotally attached to the rearward leg of the frame  72 , to travel along the ball screw. As the nut moves, the rearward leg of the frame  72  may pivot 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  may be calibrated in one degree increments. Permitting the frame  72  to pivot through an angle of up to about 10 degrees may be sufficient for most applications. 
     The butt joint may be stronger and more stable during the tire manufacturing process if it is covered with a gum strip laid perpendicularly across the butt joint. For an efficient operation, the gum strip applier  44  may operate simultaneously with the butt splicer  36 . Therefore, the gum strip applier  44  may be 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 may be positioned at a location suitable for a gum strip to be applied by the gum strip applier  44 . 
     Referring to  FIG. 18 , the outfeed conveyor  108  may be supported by a base  126 . The gum strip applier  44  may have a frame  127  independently supported by a base  128  and legs  129 . Thus, the outfeed conveyor  108  and gum strip applier  44  may be positioned independently with respect to the butt splicer  36 . The gum strip applier  44  may be positioned such that when a butt splice is formed on the butt splicer  36 , a previously made butt splice may be located on the 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. 19 , the gum strip applier  44  may have a gum strip conveyor  142  and a vacuum head assembly  144 . The vacuum head assembly  144  may have two degrees of freedom permitting removal of a gum strip from the strip conveyor  142  and placement a butt splice positioned at the upstream location  140 . 
     Referring to  FIG. 20 , an X-axis horizontal drive motor  146  may be mechanically connected to one end of a ball screw  148 ; and a sprocket  150  may be mounted on an opposite end of the ball screw  148  for operatively engaging a timing belt  152 . The timing belt  152  may be further connected to a second sprocket  154  mounted on an end of a second ball screw  156 . The ball screws  148 ,  156  may have respective ball nuts  158 ,  160  that support and carry a carriage  162  supported and guided in linear motion by linear bearings  163 . As shown in  FIG. 20 , the carriage  162  may support the vacuum head assembly  144 . The vacuum head assembly  144  may have a length substantially equal to the length of the butt splice (e.g., the full width of the preparation ply strip). Rotation of the horizontal drive motor  146  may simultaneously move the ball nuts  158 ,  160  ( FIG. 20 ), 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. 21 , a Z-axis vertical drive motor  164  may be mounted on, and supported by, the carriage  162  and may be mechanically connected to one end of a first ball screw  166 . A first timing sprocket  168  may be mounted on an opposite end of the first ball screw  166  and operatively engage 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  may be rotatably mounted on the respective ball screws  166 ,  178  and connected to a vacuum head plenum  180 , which is guided in linear motion by linear bearings  181 . 
     Referring to  FIG. 19 , a vacuum head  182  may be supported by vertical posts  184  fixed to the plenum  180 . Biasing components, such as compression springs  181 , may be mounted on the posts  184  between the vacuum head  182  and the plenum  180 . The vacuum head  182  may have a length extending across substantially the entire width of the outfeed conveyor  108 , as well as the length of a butt splice in the preparation ply strip. Thus, operation of the vertical drive motor  164  may raise the vacuum plenum  180  and the vacuum head  182  below the outfeed conveyor  108 . 
     Referring to  FIG. 10 , the controller  98  may provide output signals to the strip conveyor motor  186  and receive input pulses from a strip conveyor encoder  188  by which the controller  98  may determine the linear motion of the strip conveyor  142 . Similarly, in response to output signals commanding the horizontal and vertical drive motors  146 ,  164 , the controller  98  may receive feedback signals from the encoders  190 ,  192  representing motion of the vacuum head  182 . The controller  98  may also operatively connect to a vacuum pump  194  that applies partial vacuum pressure to the plenum  180 . A vacuum may be applied and released by the vacuum head  182  by means of a vacuum release valve  196  connecting the vacuum head plenum  180  and the vacuum head  182 . When in its first state, the valve  196  may close the vacuum head  182  to atmosphere and open it to the  180  thereby applying a partial vacuum to the vacuum head  182 . In its opposite second state, the valve  196  may close the connection between the vacuum head  182  and the plenum  180  and open the vacuum head to atmosphere thereby dissipating the partial vacuum therein. The controller  98  may also connect to a solenoid  94   e  for changing the state of a knife cylinder  198  thereby operating a knife  200  on the gum strip preparation equipment  48  ( FIG. 5 ) to cut the gum strips to desired lengths. 
     There may be three independent, but coordinated, operations or subroutines executed by the gum strip applier  44 . Referring to  FIG. 19 , first a gum strip  42  may be moved by the conveyor  142  to a location ready for transfer to the vacuum head  182 . A second operation allows 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 may apply the gum strip to the butt joint after the butt joint has been moved to the desired location  140  ( FIG. 18 ). Referring to  FIGS. 10, 19, and 22 , to cut a gum strip to length, the controller  98  may provide, 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  feeds, the controller  98  may monitor and count output pulses from the strip conveyor encoder  188 . When the controller  98  counts, at  554 , a number of pulses equal to the desired length of the gum strip, the controller may provide, at  556 , a “STOP” output signal to the strip conveyor motor  186 . Thereafter, the controller  98  may provide, at  558 , an output signal commanding the solenoid  94   e  to change state thereby porting pressurized air to the knife cylinder  198  and operating the knife  200 . Immediately thereafter, an output signal from the controller  98  may change state thereby reversing the state of solenoid  94   e  and returning the knife cylinder  198  to its initial position. Operation of the knife cylinder  198  may reciprocate the knife  200  and establish a cut end for the gum strip  145 . This action may provide a gum strip on the strip conveyor  142  that is of the desired length (e.g., the length of the butt strip  40 ). 
     Thereafter, the controller  98  may provide, at  560 , a “START” output signal to the strip conveyor motor  186 ; and the strip conveyor  142  may transport the gum strip  42  across the width of the outfeed conveyor  108 . Again, the controller  98  may monitor and count output pulses from the strip conveyor encoder  188  and determine when the cut gum strip is in its desired position. When that position is detected, at  562 , the controller  98  may provide, at  564 , a “STOP” output signal to the strip conveyor motor  186 . At this point, a gum strip  42  of desired length may be located on the strip conveyor  142  at a location ready to be picked up by the vacuum head  182 . 
     Referring to  FIGS. 10, 18, and 23 , to pick up the gum strip from the gum strip conveyor  142 , the vacuum head  182  may elevated and the carriage  162  may be 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 controller  98  may provide, 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 plenum  180 . A vacuum may then be applied to the vacuum head  182 . The controller  98  may also provide, 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 controller  98  may monitor and count output pulses from the vertical drive encoder  192  and detect, 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  may be sufficiently close to the strip conveyor  142  such that the vacuum head  182  may lift the gum strip off the gum strip conveyor  142 . 
     The controller  98  may then provide, at  567 , output signals to the Z-axis vertical drive motor  164  and the X-axis horizontal drive motor  146  causing the vacuum head  182  to move to a ready position immediately above the location  140  at which the butt joint is located. The controller  98  may 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 ,  164  may operate simultaneously to move the vacuum head  182  to a ready position. 
     The controller  98  may monitor output pulses from the encoders  190 ,  192  in the manner previously described to detect, at  568 , which the vacuum head  182  is at the ready position. Thereafter, the controller  98  may provide, at  569 , output signals to either or both the motors  146 ,  164  commanding them to stop the vacuum head  182  at the ready position. 
     Referring to  FIGS. 10, 18, 19, and 24 , to apply the gum strip to the butt joint, a butt joint may be moved to the location  140  beneath the vacuum head  182  at the ready position. The controller  98  may provide, 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 may have a length extending over substantially the entire length of the butt splice. Further, the gum strip may have a width extending across the butt splice  40  and over a portion of the major surfaces on both sides of the butt splice. The vacuum head  182  may be resiliently and movably mounted to the vacuum head plenum  180 . Therefore, as the vertical drive motor  164  continues to move the plenum  182  downward, the vacuum head  182  may contact the preparation ply strip  38  and the springs  181  may apply a downward biasing force against the vacuum head  182  thereby applying a desired application force against the gum strip  42 . That force may be determined by spring constants of the springs  181  and may be effective to cause adhesive on the gum strip  42  to better adhere to the preparation ply strip  38 . 
     Again, the controller  98  may monitor the output pulses from the encoder  190  and detect, at  573 , when the vacuum head  182  has been moved to its lowermost position. Thereafter, the controller  98  may provide, at  574 , a “STOP” output signal to the vertical drive motor  164 . In addition, the controller  98  may provide 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  180  and the vacuum head  182  is blocked and the vacuum head  182  is open to atmosphere. At this point, the controller  98  may allow the vacuum head  182  to remain at its lowermost position and allow the adhesive on the gum strip to set. Such a time may be determined by an internal timer in the controller  98  and may be set from zero to any desired number of seconds. 
     Thereafter, the controller  98  may provide, at  575 , output signals commanding the drive motors  146 ,  162  to move the vacuum head  182  back to the pickup position above the gum strip conveyor  142 . As described above, the controller  98  may monitor the encoders  190 ,  192  to detect, at  576 , when the vacuum head  182  is at the pickup position; and thereafter, at  577 , the controller may provide “STOP” output signals to the drive motors  146 ,  164 . 
     As described above, it may be 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  40  while the butt splicer is splicing the next cut piece  32  to the preparation ply strip  38 . Therefore, prior to a butt splice  40  being moved to the position  140 , the gum strip applier  44  may prepare a gum strip  42  for application. 
     Several of the above processes and subroutines may occur simultaneously. For example, while a butt splice  40  is being made ( FIG. 16 ) and a gum strip  42  is being applied over a previously made butt splice ( FIG. 24 ), another gum strip  42  may be cut to size and moved into the gum strip applier  44  ( FIGS. 22 &amp; 23 ).  FIG. 25  is a state diagram of a program for the controller  98  permitting several operations or subroutines to operate simultaneously. 
     If, at  580 , there is no gum strip  42  on the gum strip conveyor  142 , the controller  98  may execute, at  581 , the subroutine of  FIG. 22  to cut a gum strip to length. If a gum strip  42  is on the conveyor  142 , the controller  98  may determine, at  582 , whether the vacuum head  182  is empty; and if so, may execute, at  583 , the subroutine of  FIG. 23  to pick up the gum strip from the conveyor  142 . If the vacuum head  182  is holding a gum strip  42 , the controller  98 , at  584 , may determine whether a butt splice  40  is in position and ready to be made. If so, the controller  98 , at  585 ,  586 , may proceed to make a butt splice  40  by executing the butt splice subroutine of  FIG. 16  and simultaneously apply a gum strip  42  to a previously made butt splice  40  by executing the subroutine of  FIG. 24 . If the controller  98 , at any time, detects, at  584 , that a butt splice  40  is not in position and ready to be made, the controller may bring a new cut piece  32  into the butt splicer  36  by executing the position preparation ply subroutine of  FIG. 11 . 
     The location of the gum strip applier  44  may be adjusted with respect to the butt splicer  36  to accommodate different widths of calendered material supplied to the infeed conveyor  34 . Referring to  FIG. 19 , each side of the gum strip applier frame  127  may have grooved rollers  136  mounted on opposite sides of a linear guide  137  attached to the base  128 . As shown in  FIG. 18 , a ball screw and nut assembly  138  may be mounted to the base  128 . A handwheel  139  may be operatively connected to the ball screw nut and may be rotatably mounted to the frame  127 . Rotation of the handwheel  139  may rotate the ball screw nut 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 may be readily accommodated. When the location of the frame  127  and gum strip conveyor  142  is changed, feeding of the gum strip  42  from the preparation equipment  48  ( FIG. 5 ) may also be adjusted, for example, by moving the location of the preparation equipment. 
     When making large (e.g., larger than 30″) pneumatic tires, as described above, calendered wire treatments may be stitched together to make a carcass band large enough to encompass the tire building drum. Large pneumatic tires ( 57 ″ and  63 ″ rim diameters) may have five or six sheets of calendered material stitched together. For example, a pneumatic tire with five sheets may have four prep splices and one builders splice. The prep splices may be uniform and consistent these splices are cut, aligned, and “zipper” stitched by precision machinery. The builders splice may be inconsistent since this splice is cut, aligned, and zipper stitched by hand. In cured pneumatic tires, a perfect splice may achieve uniform spacing close to what the “as calendered” one-piece material achieves. This is called 100% spacing. If zipper stitched material spreads more than the distance between adjacent cords, the splice may be rated on a percentage stretch level. Splices that approach 100% spacing produce increased durability of the tire casing. 
     As described above, conventional methods rely on human tire builders to hand cut ply treatment between the steel cords, splitting the rubber between those cords that may be only 0.040″ of an inch thick. This may result in inconsistent rubber amounts being left that are stitched together and splices that vary in spacing a large amount. A splice in accordance with the present invention may allow human tire builders to use wire cords in the ply treatment as a guide for cutting each side to be joined flush against the wire cord thereby leaving no material within the splice to be stitched. A 0.020″ wrap around gum strip may be applied around the guide cord to both sides of the splice resulting in uniform gauge between the guide cords to be zipper stitched. Splice quality and consistency may be greatly improved. 
     As shown in  FIGS. 1-3 , both edges  221 ,  222  of two plies  211 ,  212  to be joined may be shaved such that the nearest wire cords  233  are exposed at the edges ( FIG. 1 ). These plies  211 ,  212  may have a substantially uniform spacing Wi between the wire cords. Only one edge  221  may then be wrapped by a gum strip  244  having a nominal thickness Ws equal to the spacing Wi between the wire cords of the plies  211 ,  212  ( FIG. 2 ). The gum strip  244  may be a material at least 20% softer than the rubber, or substrate, material of the plies  211 ,  212 . The gum strip  244  may wrap around the edge  221  such that the gum strip forms a U-shaped structure in section that allows the gum strip to extend from a first side of the ply  211  over the edge  221  of that ply to a second side of that ply  211  ( FIG. 2 ). The edges  221  may be placed in abutting relationship with the other ply  212  with the gum strip  244  therebetween ( FIG. 3 ). The plies  211 ,  212  may thereby be stitched together while preserving or maintaining the uniform spacing Wi between the wire cords. These stitches  255  may each extend from a first planar side of the first ply  211  to a first planar side of the second ply  212  and from the gum strip  244  to the first planar side of the second ply ( FIG. 3 ). 
     While the present invention has been illustrated by a description of various examples and while these examples have been described in considerable detail, it is not the intention of Applicant 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 a described example, the engagement actuators  85 ,  90  and clamping actuator  82  are described as pneumatic cylinders; as will be appreciated, in alternative example, those actuators may be hydraulic actuators or electromechanical drive systems or other suitable drive systems. 
     Therefore, the present 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.