Machine for spirally wrapping a continuous element around an annular tire bead
BACKGROUND OF THE INVENTION 
     The invention is designed for use in a machine which spirally wraps a cord or tape around an annular tire bead used in the building of pneumatic tires. Machines of this type operate at extremely high speeds and it is difficult to stop operation of the machine at a point where the bead wrapping apparatus comes to a halt at a particular desired position which does not necessitate resetting of the machine for wrapping another bead. Such machines presently use what might be termed positive braking action, where a sharply defined abutment of a moving member abruptly comes to a halt against the rigid stop of a stationary member. The abrupt halt of a rotating member when such braking action is applied has a shattering effect upon the machine. It is desired to bring the machine to a quick, but gentle halt by cushioning the stoppage of the rotating parts of the machine. The invention is designed to accomplish this. 
     Briefly stated, the invention is in a machine for spirally wrapping a continuous element, such as a cord or tape, around an annular tire bead. The machine comprises a series of inter-related and connected moving parts, one of which is an apparatus for wrapping the continuous element around a rotating tire bead. A braking mechanism is provided to bring the bead-wrapping apparatus to a cushioned halt. The braking mechanism comprises a conventional electro-brake type device for slowing down the rotation of the bead-wrapping apparatus, and a latching mechanism which takes over and brings the bead-wrapping apparatus to a halt at a desired position for wrapping another bead. 
    
    
     DESCRIPTION OF THE DRAWING 
     The following description of the invention will be better understood by having reference to the annexed drawing, wherein: 
     FIG. 1 is a front view of a bead-wrapping machine made in accordance with the invention; 
     FIG. 2 is a rear view of the machine; 
     FIG. 3 is a right side view of the machine; 
     FIG. 4 is a left side view of the machine; 
     FIG. 5 is an enlarged view of the knife assembly of the machine; and 
     FIG. 6 is a schematic of the wiring of the machine. 
    
    
     ENVIRONMENT OF THE INVENTION 
     With reference to FIGS. 1-4, there is shown a machine 10 for spirally wrapping a continuous element 11, such as a cord or tape, around an annular tire bead 12. The machine 10 essentially comprises a machine stand 13 for supporting an assembly 14 for holding and rotating the tire bead 12, an assembly 15 for holding and wrapping the continuous element 11 around the rotating bead 12, an assembly 16 for braking and stopping operation of the machine 10, an assembly 17 for controlling the rotational speed of the tire bead 12, an assembly 18 for regulating the speed at which the continuous element 11 is wrapped around the rotating tire bead 12, and an assembly 19 for cutting the continuous element 11 after the wrapping operation is completed. 
     Assembly for Rotating the Tire Beads 
     The assembly 14 for holding and rotating the tire bead 12, hereafter referred to as the bead rotating assembly or BRA 14, comprises a shaft 20 with a rotatable head 21. The shaft 20 is pivotally mounted on the machine stand 13, so that the head 20 can be rotated to and from the assembly 15 for wrapping the continuous element 11 around the tire bead 12. A spring-biased flange roll 22 is pivotally mounted on the shaft 20 for rotation to and from the rotatable head 21. The flange roll 22 carries a cam follower 23 for engaging a cam 24 projecting from the machine stand 13 to cause rotation of the flange roll 22 into compressive engagement with the tire bead 12 when it is positioned on the machine 10 between the flange roll 22 and the rotatable head 21. The tire bead 12 is rotated in a fixed plane and at a predetermined desired speed corresponding to the rotational speed of the rotating head 21. The BRA 14 carries a pin 25 for engaging and actuating a conventional limit switch 26 on the machine stand 13. An air cylinder 27 and reciprocating piston 28 are coupled between the machine stand 13 and the shaft 20 to rotate the BRA 14. 
     An electric motor 29, mounted on the machine stand 13, is operatively connected to the BRA 14 to rotate the head 21 of the shaft 20. A drive pulley 30 is secured to the protruding shaft 31 of a conventional clutch and electro-brake device 32 which, in turn, is mounted on the protruding shaft of the electric motor 29. A good clutch and brake device 32 is one manufactured by the Warner Electric Company of Beloit, Wisconsin. A clutch and electro-brake device 32 of this type employs a first disc which is keyed to the rotating shaft of the electric motor 29, and a second disc which is secured so that it will not rotate. A magnetic field is developed to move the rotating disc against the stationary disc to stop operation of the electric motor 29 and machine 10. It can be appreciated that the rotatable disc of the electro-brake 32 is akin to a brake drum, whereas the stationary disc is like a brake shoe. The clutching mechanism of the device 32 is used to engage and disengage the rotating shaft of the electric motor 29 from the rotatable shaft 31 of the device 32. As best seen in FIGS. 1 and 4, the rotatable head 21 of the BRA 14 is coupled to the pulley 30 of the electric motor 29 by a series of interacting gears, pulleys, and connecting drive belts. 
     Assembly for Controlling the Rotational Speed of the Tire Beads 
     The assembly 17 for varying the rotational speed of the tire beads 12 comprises a hand-operated lever 35 which is rotated to different arcuate positions for changing the spacing between the outer ends 36 and 37 of the drive pulley 38 to literally change the diameter of the drive pulley 38 and, accordingly, vary the speed at which the drive pulley 38 and connected head 21 rotate. 
     Assembly for Wrapping the Tire Bead 
     The assembly 15 for wrapping the continuous element 11 around the rotating bead 12, hereafter referred to as the bead wrapper assembly or BWA 15, comprises an annular carriage or shuttle 39 with a pie-shape portion 40 thereof removed for receiving the tire bead 12. The shuttle 39 is rotatable in a fixed plane and about a fixed center axis. The shuttle 39 is likewise coupled to the drive pulley 30 of the electric motor 29 by a series of interacting pulleys and connecting drive belts. The shuttle 39 carries a spindle 41 for rotatably supporting a spool 42 on which the continuous element 11 is helically wound. The continuous element 11 is taken from the spool 42, reeved around a guide pulley 43, and threaded on a finger guide 44 which is adapted to receive differently sized continuous elements, such as a tape or cord. The finger guide 44 comprises two guide rolls 45, 46 between which the continuous element 11 passes. The shuttle 39 has an outer periphery with projecting gear teeth for meshing engagement with other toothed gears which, in turn, are coupled to a latching mechanism which is part of the brake assembly 16. 
     Assembly for Braking and Stopping Operation of the Machine 
     The assembly 16 for braking and stopping operation of the machine, hereafter referred to as the brake assembly 16, besides including the electro-brake 32, includes a latching mechanism in the form of a circular cam 47 which is geared for rotation, in unison, with the shuttle 39. The cam 47 has a specially configured V-shaped recess 48 for receiving a cam follower 49 comprised of a roller 50 which is rotatably mounted on the free end of an L-shaped lever arm 51 that is pivotally mounted on the machine stand 13 adjacent the cam 47. An air cylinder 52 and reciprocating piston 53 are coupled between the cam follower 49 and machine stand 13 to rotate the cam follower 49 into and out of latching engagement with the cam 47. The V-shaped recess 48 is rounded to matingly conform to the curvature of the roller 50. The outer corners of the recess 48 are also rounded to facilitate movement of the roller 50 into and out of the V-shaped recess 48. The cam 47 is designed to override the cam follower 49 when it is rotating too fast, i.e. above a desired rotational speed. 
     Assembly for Controlling the Wrapping of the Tire Bead 
     The assembly 18 for regulating the wrapping of the tire bead, by controlling the rotational speed of the shuttle 39, comprises a hand wheel 55 for varying the diameter of the main drive pulley in the drive chain of the BWA 15. 
     Assembly for Cutting the Continuous Element 
     The assembly 19 (FIG. 5) for cutting the continuous element 11, hereafter referred to as the knife assembly 19, comprises a sharp knife or blade 56 which is coupled to an air cylinder 57 that is used to reciprocate the knife 56 to and from a stationary holder 58 for housing the knife blade 56. A hook 59 is formed in the free outer end 58 of the knife 56 protruding from the holder 58. The knife 56 when actuated, moves outwardly from the holder 58 to a point where the hook 59 passes beyond the continuous element 11. The curved, outer edge 60 of the hook 59 deflects the element 11 which finally comes to rest adjacent the inside cutting edge 61 of the hook 59, as shown in dotted line of FIG. 5. The continuous element 11 is cut by the sharp edge 61 of the hook 59 when the knife 56 moves back into the holder 58 and comes to rest against the roll pin 62. The cut end of the element 11, carried by the finger guide 44, is retained by the knife 56 and holder 58, until the shuttle 39 begins rotating, at which time the rotating finger guide 44 will pull the cut end of the element 11 from between the knife 56 and holder 58. Thus, the operator of the machine 10 will not have to reach into the shuttle to retrieve the loose cut end for starting the wrap of a new bead, as has been done in the past. 
     As has been previously explained, the brake assembly 16 is designed to cushion the stop of the main moving parts of the machine 10, especially the rotating shuttle 39, so that they will not come to an abrupt halt. For this reason, the cam 47 has been designed to override the cam follower 49 if rotating too fast. Although the electro-brake 32 and latching mechanism 47, 49 of the brake assembly 16 cooperate to stop operation of the machine 10, it was discovered that the stoppage of the machine 10 was haphazard in that the shuttle 39 did not always come to rest in its desired position, as best seen in FIG. 3, where the roller 50 of the cam follower 49 is in the V-shaped recess 48 of the cam 47. 
     The Invention 
     It was determined to apply the electro-brake 32 for a predetermined length of time to slow down the rotation of the cam 47 sufficiently so that the roller 50 of the cam follower 49 always comes to rest in the configured recess 48 of the cam 47. This was accomplished by providing a pair of conventional vane switches 63, 64 (FIG. 2) for monitoring the rotation of a pair of vanes 65, 66 which are operatively connected to the drive mechanism of the shuttle 39, so that the vanes 65, 66 rotate, in unison, with the shuttle 39. One of the vane switches 64 counts the number of wrappings by sending an electrical impulse to a digital counter 67 (FIG. 3) for every rotation of the shuttle 39. The digital counter 67 provides a visual display 68 of the number of revolutions of the shuttle 39, or wrappings of the continuous element 11 around the rotating tire bead 12. The digital counter 67, just prior to the completion of the final wrap of the desired number of wraps, triggers operation of the electro-brake 32 and a conventional timer 69 (FIG. 6) for regulating the time of contact between the rotating and stationary discs of the electro-brake 32. The timer 69 causes disengagement of the discs of the electro-brake 32, after a period of time sufficient to slow down the rotation of the cam 47 so that the cam 47 will not override the cam follower 49; that is, the roller 50 of the cam follower 49 will always come to rest in the V-shaped recess 48 of the cam 47. This braking feature of the machine can further be explained by reference to FIG. 6 in a discussion of the operation of the machine 10. 
     Operation of the Machine 
     Assuming a spool 42 of a continuous element 11 is properly mounted and threaded on the shuttle 39, a tire bead 12 is properly positioned on the bead wrapper assembly 14, as shown in FIG. 3, and the free end of the continuous element is attached properly to the bead 12, then a start switch 70 is closed to begin operation of the machine 10. The start switch 70 actuates the starting mechanism M of the motor 29 and a solenoid 71 which commences operation of the air cylinder 27 to rotate the bead rotating assembly 14 into position where the tire bead 12 is adjacent the finger guide 44. The limit switch 26 is actuated by the pin 25 as the bead rotating assembly 14 moves into position. The limit switch 26 operates a control relay CR 72 for the clutch and electro-brake device 32, which is coupled between the electric motor 29 and the assemblies 14, 15 for rotating and wrapping the tire bead 12. The shuttle 39 starts rotating to wrap the continuous element 11 around the bead 12 which is also rotating at a speed that is correlated to the rotational speed of the shuttle 39. The vane switch 64 keeps track of the number of wrappings. Just prior to the final wrap, the digital counter 67 actuates operation of the electro-braking device 32 to slow down the rotating cam 47. Simultaneously, the brake release timer (TDDI) 69 and an end-of-cycle timer (TDD) 73 are operated for timing and releasing the braking action of the electro-brake device 32 when the cam 47 is sufficiently slowed down. A second solenoid 74 is actuated by the digital counter 67 (CTR) to operate the air cylinder 52 for moving the cam follower 49 into position for stopping the rotating cam 47. When the cam 47 comes to a halt, the second vane switch 63 is closed and reacts to operate a second control relay (CRI) 75 which controls a third solenoid 76 to begin operation of the knife assembly 18, whereby the knife 56 moves from its holder 58, hooks the continuous element 11 and brings the hooked element 11 back to the holder 58 where it is cut by the sharp edge 61 of the knife 56. The second control relay 75 reacts to move the bead rotating assembly 14 back to its rest position to release the wrapped bead 12 after the continuous element 11 is cut. The shaft 31 of the electro-brake device 32, has meanwhile been disengaged from the rotating shaft of the electric motor 29. The machine 10 is now ready for the placement of a new bead for wrapping. 
     Thus, there has been described a highly improved machine for wrapping a continuous element, such as a cord or tape, spirally around a tire bead.