Tire tread skiving machine

A tire tread skiving machine having an elongated frame with two spaced ends. An elongated cutting platen extends transversely across the frame between the two ends. An infeed conveyor conveys extrusions to the cutting platen while an outfeed conveyor conveys extrusions away from the platen. A rail assembly is mounted to the frame above the cutting platen and a carriage is movably mounted to the rail assembly. A rotatably driven skiving blade is mounted to the carriage and cuts the extrusion at the cutting platen as the carriage moves along the rail assembly. The rail assembly is pivotally mounted to the frame so that the dynamically variable angle of the cut made by the skiving blade may be varied.

BACKGROUND OF THE INVENTION

I. Field of the Invention

The present invention relates generally to a tire tread skiving machine or rubber industry.

II. Description of Related Art

In the production of tires for automotive vehicles, a synthetic rubber extrusion is conveyed by a conveyor to a cutting platen. At the cutting platen, a skiving blade performs the cut through the extrusion to form a length of the extrusion corresponding exactly to the required length of tire tread which can be adjusted on the fly for the particular automotive vehicles. Different tire sizes, of course, require different lengths, widths and thickness of tire tread.

Each end of the tire tread extrusion is cut to a precision angle. Consequently, when the tire tread is wrapped around the carcass for the tire the two ends of the extrusion ideally meet in a flush fashion to complete the tread. The overall tire is then vulcanized to complete the manufacture of the tire.

One difficulty of these previously known machines for cutting tire treads from a synthetic rubber extrusion is that the angle of the cut through the extrusion is fixed and cannot be dynamically varied. While that fixed angle is satisfactory for many automotive vehicle tire applications, in some cases, a fixed angle of the cut through the tire tread extrusion is unacceptable. For example, it has been discovered that high-speed tires of the type used by racing cars experience a “speed bump” each time the tire rotates around the junction of the two ends of the tire tread extrusion. This “speed bump” can result not only in excessive tire wear, but also undesirable vibration in the vehicle.

A still further disadvantage of these previously known tire tread skiving machines is that the tire tread extrusion is extremely tacky following the extruding operation. As such, even after the skiving blade formed the cut through the tire tread extrusion, the high tackiness of the ends of the tire tread extrusion around the cut would cause adjacent tire treads to stick together. This, in turn, required that the tire tread extrusion discarded.

SUMMARY OF THE PRESENT INVENTION

The present invention provides a tire tread skiving machine which overcomes all of the above-mentioned disadvantages of the previously known machines.

In brief, the skiving machine of the present invention comprises an elongated frame having two spaced ends. An elongated cutting platen extends transversely across the frame between the two ends of the frame.

An infeed conveyor is mounted to the frame and extends from one end of the frame to the cutting platen. This infeed conveyor is adjustable and independent to the outfeed conveyor adapted to move a tire tread extrusion perpendicular to the cutting platen.

Similarly, an outfeed conveyor is also mounted to the frame and extends from the cutting platen to the other end of the frame. This outfeed conveyor is adjustable and independent to the infeed conveyor adapted to move a tire tread cut from the extrusion away from the cutting platen following the cutting operation.

A rail assembly is mounted to the frame so that the rail assembly overlies the cutting platen. A carriage is movably mounted to the rail assembly and is movable in a direction parallel to the cutting platen and thus transverse to the longitudinal axis of the frame.

A rotatably driven skiving blade is mounted to the carriage so that the skiving blade registers with the cutting plane. Consequently, as the carriage is moved along the cutting platen, the skiving blade contacts and cuts a tire tread extrusion positioned at the cutting platen.

The rail assembly is pivotally mounted to the frame. Consequently, by varying the pivotal position of the rail assembly, the angle of cut of the skiving blade through the tire tread extrusion may be altered as desired and also is dynamically adjustable.

With reference first toFIG. 1, a preferred embodiment of a tire tread skiving machine20is shown for cutting tire treads from a tire tread extrusion22. The tire tread extrusion22is typically constructed of a synthetic rubber, although other materials may alternatively be used.

The machine20includes an elongated frame24, preferably made of stainless steel, which is supported on a ground support surface. An infeed conveyor26extends from one end28of the frame24to a cutting platen30. Similarly, an outfeed conveyor32is also mounted to the frame24. The outfeed conveyor32extends from the cutting platen30to an outfeed end34of the frame24.

Both the infeed conveyor26as well as the outfeed conveyor32are preferably belt conveyors. A first motor36drives the infeed conveyor26while a second motor38drives the outfeed conveyor32, and both motors are able to have independent adjustable feed rates.

Both motors36and38are precision motors, such as DC servo motors, and are operated under the control of a controller40. The controller40may be of any conventional construction, such as microprocessor based, hardwired, or the like. Furthermore, as will become hereinafter apparent, the controller40not only controls the activation of the conveyor motors36and38, but also other operations of the machine20.

With reference now particularly toFIGS. 1,11and12, the cutting platen30overlies a portion of the inner end of both the infeed conveyor26as well as the outfeed conveyor32. As such, the cutting platen extends transversely across the frame24in a direction perpendicular to the direction of movement of the conveyors26and32and thus of the extrusion22.

With reference now particularly toFIGS. 1,3and4, a generally rectangular rail assembly42is pivotally mounted on one side by pivot pins44to the frame24so that the rail assembly42overlies the cutting platen30. Two or more arcuate legs46extend downwardly from the rail assembly42on the side opposite from the pivot pins44. These arcuate legs46are received in like shaped channel members48attached to the frame. Preferably, one arcuate leg46and its associated receiving channel48are provided at each end of the rail assembly42.

In order to change the pivotal position of the rail assembly42, a motor50(FIG. 1) is mounted to the frame24and simultaneously rotatably drives a pair of ball screw actuators52through a shaft. One end of each ball screw actuator52is secured to the frame24while the upper end of each ball screw actuator52is pivotally secured to the rail assembly42by a pivot connection54. Consequently, actuation of the motor50varies the pivotal position of the rail assembly42as shown inFIGS. 3 and 4. Once the rail assembly42is pivoted to the desired position, the controller40actuates a lock56to securely attach the arcuate leg46to its associated channel member48and thus rigidly secures the rail assembly42to the frame24in its adjusted pivotal position.

It will be understood, of course, that the two pivotal positions illustrated inFIGS. 3 and 4of the patent drawing are by way of example only. In practice, the pivotal position of the rail assembly42may be finitely adjustable between the extremes of the pivotal movement of the rail assembly42. Similarly, although ball screws52are illustrated as the preferred fashion to pivot the rail assembly42, it will be understood that any other type of mechanical connector may alternatively be used to pivot the rail assembly42to the desired pivotal position.

With reference now toFIGS. 1,9,10and13, a carriage60is slidably mounted to the rail assembly42so that the carriage60is movable in a direction parallel to the cutting platen30and thus in a direction transverse to the direction of movement of the conveyors26and32. Although any means may be used to move the carriage60along the rail assembly42, preferably a motor62, such as a stepping motor or servo motor, is mounted to the carriage and rotatably drives a pinion64in mesh with a rack65(FIG. 13) mounted to the rail assembly42. Consequently, rotation of the motor62drives the carriage60in the direction indicated by arrow66inFIG. 9while rotation of the motor62in the opposite direction drives the carriage60in the direction of arrow68shown inFIG. 10. The controller40controls the activation of the motor62and thus the speed, direction and position of the carriage60.

Referring now toFIGS. 14 and 15, a slide70is mounted to the carriage60. This slide70is movable in a direction transverse to the direction of movement of the carriage60between an operating position, shown inFIG. 14, and a retracted position, shown inFIG. 15. An actuator72, such as a pneumatic actuator, controls the position of the slide70. The operation of the actuator72is also controlled by the controller40.

A motor74is mounted to the slide72, which, when activated, rotatably drives a skiving blade76. As best shown inFIG. 12, with the slide70in its operating position and the carriage60positioned on one side of the tire tread extrusion22, the skiving blade76registers with the tire tread extrusion22. Consequently, upon actuation of the carriage motor62, the carriage60is driven laterally across the cutting platen32to form the cut through the extrusion22. After the cutting operation, the actuator72moves the slide70to its retracted position so that the skiving blade76is spaced upwardly and away from the extrusion22. Thus, upon reverse activation of the carriage motor62and movement of the slide70to its operating position, the carriage60is retracted to its original position in preparation for the next cutting operation.

With reference now toFIGS. 11 and 12, the cutting platen30is there shown in greater detail. The cutting platen30includes a first portion80which overlies and is substantially flush with the infeed conveyor26as well as a second portion82that is flush with and overlies the end of the outfeed conveyor32. A cutting well84is formed in between the portions80and82of the cutting platen30and this well84is dimensioned to register with and receive the skiving blade76without contacting the blade76when the slide70, and thus the skiving blade76, are in their operative position. Additionally, the platen30preferably includes a telescopic cutting platen section31(FIG. 16) that extends during a low degree angle, e.g. 8 degrees, cut with water bubbler assist holes to support the rubber extrusion during the cutting process and aid to the stick-slip condition that occurs on the tread while being advanced to the next cut length. Actuators33(FIG. 16), such as air cylinders, control the movement of the platen section31and move the platen section31to an extended position for low angle cuts. For higher angle cuts, the actuators33move the platen section31back to the retracted position.

The second portion82of the cutting platen30, however, has the capability to be spaced slightly lower than the first portion80of the cutting platen30to optimize the cutting condition. Thus, during a cutting operation, the extrusion22drops down onto the second and lower portion82of the cutting platen. This, in turn, eliminates potential contact between the cut ends of the extrusion22and thus prevents the cut ends of the extrusion22from re-adhering to each other and the conveyors have the capability to pull the tread at different feed rates to assist in the separation of the tread.

With reference now toFIGS. 5-8, the operation of the skiving machine20will be described. It will be understood, of course, that many components of the skiving machine20have been removed inFIGS. 5-8for clarity.

With reference now toFIG. 5, after a cutting operation, the slide70together with the skiving blade76are moved to the retracted position so that the skiving blade76is spaced upwardly from the extrusion22. In this position, the carriage60is moved to its retracted position as shown by arrow90under control of the controller40until the blade76is positioned to one side of the extrusion22.

With reference now toFIG. 6, the controller40activates the actuator72to move the slide72, and thus the skiving blade76, into an operative position as shown by arrow92. In its operative position, the skiving blade76registers with the extrusion22supported on the cutting platen30and so that the skiving blade76registers with the well84and the cutting platen30.

With reference now toFIG. 6, in order to perform the skiving or cutting operation, the controller40activates the carriage motor62to drive the carriage60in the direction of arrow94and thus across the extrusion22to form the desired cut through the extrusion22. The controller40then moves the slide70to its retracted position, as shown by arrow96inFIG. 8, whereupon the process beginning inFIG. 5is repeated.

With reference now toFIG. 2, following the cutting operation, the controller40first activates the outfeed conveyor32for a period of time prior to activation of the infeed conveyor26. This forms a space in between the cut tire treads on the outfeed conveyor32to prevent adhesion of the ends of adjacent tire treads together.

With reference again toFIGS. 5-8, in the preferred embodiment of the invention, the controller40is programmed so that the stroke of the carriage60along the rail assembly42is sufficient to completely cut through the extrusion22. Since the width of the extrusions22may vary from one type of tire and to the next, the stroke or travel of the carriage60preferably varies under control of the controller40to accommodate different tire tread widths while avoiding unnecessary travel of the carriage60along the rail assembly42.

Similarly, it will be understood that following the cutting operation indicated inFIG. 6, and during the retraction of the carriage assembly60illustrated inFIG. 5, the infeed conveyor26is activated to move a next length of extrusion into position over the cutting platen30in preparation for the next cutting operation. The controller40controls the activation of the infeed conveyor26in order to position the required length of extrusion on the outfeed conveyor32from the cutting platen30in accordance with the diameter of the tire for which the tire treads are cut. Additionally, the angle of the cut through the extrusion22may be varied at any desired time between cutting operations to change the pivot angle of the rail assembly42in the fashion previously described.

From the foregoing it can be seen that the tire tread skiving machine of the present invention provides many advantages over the previously known skiving machines. In particular, the angle of cut at the ends of the tire tread may be varied as desired in order to optimize the performance of the final tire. Furthermore, since the controller40precisely controls not only the infeed conveyor26, but also the outfeed conveyor32, the precise length of the cut tire treads may be carefully controlled to obtain the desired length and width of the cut required on the tire treads. As such, additional cutting of the tire treads to obtain the correct length and angle for the tire treads is unnecessary done on additional equipment in the plant prior to the final assembly.

Having described my invention, however, many modifications thereto will become apparent to those skilled in the art to which it pertains without deviation from the spirit of the invention as defined by the scope of the appended claims.