RELATED APPLICATION DATA

This application claims the benefit of US provisional application serial no.

62/797,520, filed on January 28, 2019, the disclosure of which is incorporated by reference herein.

BACKGROUND

The disclosure is directed to a method and apparatus for transverse cutting of product material via an orbital saw assembly. The orbital saw assembly includes a rotating saw head with at least one rotating saw blade. A linear-rotary motor drives a saw blade axially and rotationally during the cut cycle as the material is being moved (e.g., conveyed on a conveyor) toward the saw blade in a direction parallel to and offset from the center axis of the linear-rotary motor. A separate motor drive assembly is used for orbital motion of the orbital saw assembly.

The production of consumer paper products such as bathroom tissue, kitchen (i.e., paper) towels, wet-wipes and the like involves cutting ribbon or logs or the web material into smaller sized product formats (e.g., rolls, wet-wipe flat packs) suitable for retail. In conventional operations, the saw blade(s) that is/are used to cut the material are set with a skew angle for each specific application so that the blades travel in a desired motion relative to the product as it is being conveyed through the cutting zone of the saw assembly. Conventional techniques require a complex system of pivot points to handle the skew angle of the saw blade, to ensure that the machine direction motion is correct, and to handle the machine direction positioning of the blade as the head rotates. For example, conventional saw head configurations can require six pivot points, as well as a motor for driving (by way of multiple belts and gearboxes) the saw blades. The blades are thus rotated by a separately mounted motor driven through a center shaft by a variety of gearboxes and belts. However, in order to adjust the skew angle, it is necessary to make a series of adjustments to various fasteners such as bolts, screws and/or pin settings, which reduces efficiency and increases downtime. Further, the above-noted complexity of conventional systems results in multiple wear points, which requires increased maintenance, and serves to increase mass and others stresses due to the type and/or amount of components that are needed to achieve the complex motion. For example, when a cut length change greater than 10 mm is desired, the saw must be stopped and an operator must enter the perimeter guarding to physically tilt the saw head to a new skew angle, representing both a safety concern and a production inefficiency.

The disclosure that follows below describes a machine and methods that avoids the above-noted problems in conventional techniques. In particular, the machine and methods described herein provides for the elimination of pivot points, gearboxes, belts and the like in connection with the driving of a saw blade used in a saw assembly for paper conversion applications. As will become evident from the description that follows below, pivot points, gearboxes, belts, and the like can be eliminated by utilizing a linearrotary motor to perform the necessary movement of the saw blade. The linear-rotary motor functions to move the saw blade both axially and rotationally, thereby serving to eliminate the pivot points, and to eliminate the multiple gearboxes and belts required by conventional systems.

A linear-rotary motor is mounted on a frame arm of the saw head, and is configured to control axial and rotational movement of a saw blade operatively coupled to the linear-rotary motor. The saw blade may be operatively coupled to the linearrotary motor with a saw blade shaft and/or by way of a separate arbor. The saw blade shaft and/or arbor may be operatively coupled to the linear-rotary motor via a coupling. The saw blade shaft and/or arbor may be journaled in and configured for linear and rotary motion in a bearing housing mounted on the saw head frame arm. The linearrotary motor and linear and rotary driven saw blade eliminates the need to provide for skew angles and complex pivot points. The conventional machine skew angle can be replicated by moving the linear-rotary motor axially in the cut zone during cutting. The saw blade rotates via a rotary function of the linear-rotary motor, thereby eliminating the need for gearboxes, belts, and the like. While the saw blade is in midst of product cutting, the motor axially moves the saw blade in a direction of conveyance of the product being cut. After the cutting is complete, the blade may continue to move at a (e.g., mathematically calculated) profile to ensure that the blade does not tug on the cut product during exit of the cut product, thereby improving the quality of the cut over conventional techniques, while also improving overall costs, efficiency and safety.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 shows an exemplary saw assembly including an indication of a direction of product material flow.

Figure 2 shows a frame arm of the saw assembly of Figure 1.

Figure 3 shows a saw blade shaft and coupling.

DETAILED DESCRIPTION

Figure 1 shows a saw assembly 100 that includes first and second saw assemblies 102a, 102b mounted on a saw head 104. The saw assemblies 102a, 102b may be linear-rotary motors with rotating saw blades 106. Although the drawings show a linear-rotary motor having an integral casing housing both the linear motor portion and the rotary motor portion, the linear motor portion and the rotary motor portion may be separate and have separate housings. Accordingly, the term linear-rotary motor should not be deemed limited to a single housing for both the linear motor portion and the rotary motor portion. The saw head 104 may be a rotating saw head providing orbital motion of the saw assemblies with the saw assemblies alternatingly moving through first and second cutting cycles relative to material to be cut which is advanced toward the respective saw assembly on a conveyor 108. In a first cutting cycle, the saw head 104 may rotate in a manner to move the first saw assembly 102a towards the material to be cut and the conveyor 108 and the second saw assembly 102b away from the material to be object and the conveyor. In a second cutting cycle, the saw head 104 may move the second saw assembly 102b towards the material to be cut and the conveyor 108 and the first saw assembly 102a away from the material to be cut and the conveyor. The rotating saw head 104 can rotate about its own shaft and center axis independent of the rotation of the saw blades 106 with a separate motor drive system (not shown). The saw head center axis is parallel to and offset from the center axes of the saw assemblies 102a, 102b. While the drawings show a first linear-rotary motor 102a on the saw head 104 and a second linear-rotary motor 102b on the saw head spaced from the first linear-rotary motor, the saw head may have one linear-rotary motor.

By way of example as shown in the drawings, each saw blade 106 rotates via a rotary function of the respective linear-rotary motor 102a, 102b connected thereto, and is moved axially via an axial function of the respective linear-rotary motor 102a, 102b. The blade 106 may be supported by way of a separate arbor or a shaft 109 that is journaled in a housing 110 of a frame arm 1 12 of the saw head 104. The housing 1 10 may be configured for linear and rotary motion of a saw blade shaft 120 or arbor therein. The separate arbor of blade shaft 109 may be joined to a separate shaft 120 of the linear-rotary motor via a coupling 122. In the alternative, the linear motor shaft 120 and saw blade shaft 109 may be integral, and may be monolithic. The coupling 122 may allow for change-out of the blade 106. The saw blade 106 may also be removable from a distal end of the saw blade shaft with a blade fastener 124. The saw blade shaft 109, the motor shaft 120 and the motor center axis may be co-axial. The saw blade may rotate about the center axis of the saw blade shaft 109 and the center axis of the motor shaft 120 when the motor is energized. Accordingly, the motor shaft 120 may move between a retracted position and an extended position relative to the motor along the center axis of the motor. When the motor shaft 120 is in the retracted position, the motor shaft extends from the motor a first distance, and wherein the motor shaft is in the extended position, the motor shaft extends from the motor a second distance that is greater than the first distance. In a similar manner, as the motor shaft is coupled to the saw blade shaft, when the motor shaft is in the retracted position, the saw blade tool holder extends from the housing a first distance, and wherein the motor shaft is in the extended position, the saw blade tool holder extends from the frame arm a second distance that is greater than the first distance. The stroke may be sized to

accommodate the travel of the material as it is advanced on the conveyor during the cut cycle.

In Figure 1 the direction advancement of the material to be cut (e.g., ribbon) is indicated by arrow B. The axial movement of the saw blade 106 matches the speed of advancement of the material in the direction of advancement during the cutting process, thereby ensuring a straight cut during conveyance of the product. While the saw blade 106 is cutting the product material, the motor 102a, 102b axially moves the saw blade 106 in the direction of advancement of the material on the conveyor 108. After the cutting is complete, the blade 106 continues to move in a manner to ensure that the blade 106 does not tug on the portion of the product cut from the material during the blade’s exit from the cut product.

As best shown in Figure 3, the linear-rotary motor 102a, 102b includes a compact housing that contains both a linear direct drive/motor and a direct rotary drive/motor. The compact housing of the linear-rotary motor 102a, 102b may comprise a cylindrical housing encompassing the linear motor portion of the linear-rotary motor, and a second cylindrical housing circumjacent the first housing encompassing the rotary motor portion of the linear-rotary motor. The linear-rotary motor shaft 120 extends from the linear-rotary motor and is driven axially by the linear motor portion and rotationally by the rotary motor portion of the linear-rotary motor. The motor shaft 120 may be hollow with a central pass-through opening in its longitudinal axis, such that compressed air, vacuum, or other media can be passed through the motor.

Each linear-rotary motor 102a, 102b may include respective cable/tube connections for attaching cables/tubes to the linear motor and the rotary motor. The cables/tubes serve as a pass-through for wires, for example. The linear motor portion and the rotary motor portion may be each controlled by a servo drive and controller (not shown), for example, and can be electrically actuated independently of each other to provide the axial and rotational movement of the saw blades. The linear-rotary motor can provide forces up to 1024 N, have a peak torque ranging from 1.5 to 8.9 Nm, have speeds up to 2,000 rpm, and stroke lengths of up to 300 mm, for example. The torque and number of turns, as well as the stroke, can all be programmed and adapted to the necessary process requirements. The linear-rotary motor can include integrated position sensors, as well as integrated temperature monitoring (none of which are shown). While use of identical linear-rotary motors is envisioned in the two-blade assembly, linear-rotary motors with different specifications could be used together.

The above-described servo drive can implement highly dynamic linear-rotary motion sequences that can be programmed to be either synchronous or completely independent of each other. The servo drive can include a compact positioning controller with one or more power elements for actuating motors, as well as an intelligent control element with integrated closed-loop position control, which handles all of the control and monitoring functions related to the servo drive. The control element can use positions defined directly by an overall system controller, or execute internally saved motion profiles using simple analog or digital signals. Connection to the controller can be made via analog, digital, or serial interfaces, fieldbuses, or ethernet, such that the servo drive is easy to integrate with any controller (e.g., PLC, industrial PC, or a proprietary controller). The servo drive and controller can, for example, operate in a wide range of power ratings at voltage levels from 24-72 VDC, or, with respect to high-power servo motors with direct drive feeds, from a three-phase grid of up to 3x480 VAC.

The saw blade 106 can be sized (e.g., up to a diameter of 1 ,200 mm) and otherwise proportioned to provide for the desired cut, and made of a suitable material (such as steel or the like). Moreover, the saw blade can be coated with a material (such as a dry film lubricant or the like) to reduce the friction coefficient between the blade 106 and the product material, increase service life, improve cut quality, decrease dust and eliminate product contamination. The saw blades can be positioned to be offset from one another in the axial direction, or to reside in the same plane with respect to the axial direction. While the present embodiment utilizes two identical saw blades, saw blades of different types (e.g., different size, material, etc.) can be used with one another as part of the two-bladed saw assembly.

A method of operating the saw assembly includes outfitting the saw assembly with the desired saw blades, and programming or otherwise operating the linear-rotary motors to provide desired axial and rotational movement to the saw blades, such that the saw blades can provide precision cuts of the passing product (e.g., ribbon) material. This includes, for example, setting the desired axial speed and rotational speed. These functions can all be controlled via the servo drive and controller. The saw assembly can be operated for the desired cutting by rotating the saw head such that the saw head and saw blades effectively function as a continuous orbital saw for cutting product material in the desired fashion.

The embodiments disclosed above improve upon conventional techniques and result in advantages in maintenance, changeover, and mechanical simplicity. Because pivot points are eliminated, multiple gearboxes and belts are not necessary, thereby reducing maintenance needs. Because the mechanical skewing of the saw head is eliminated, cut length changes can be made more readily, thereby improving process application changeover. By way of the simplified design, mechanical costs of the saw assembly are decreased, as well as overall part count and assembly time.

As various modifications could be made in the constructions and methods herein described without departing from the scope of the invention, it is intended that all matter contained in the foregoing description and shown in the accompanying drawings shall be interpreted as illustrative and not as limiting. The breadth and scope the present invention should not be limited by any of the above described exemplary embodiments.