Patent Application
20180117786
Many industries use die cutting, laser cutting, printing, embossing, or stamping to create a series of patterns on a continuous strip of material or web of material by passing the material between a pair of cooperatively rotating rotary die cylinders. This technique may be used, for example, to cut holes or other patterns onto a printed strip of material at desired locations relative to indicia printed thereon. When the patterns are positioned at specific locations relative to each other or relative to pre-applied indicia, the patterns are said to be “in registration.”
Registration may be achieved with a controller or other control device. The controller maintains a die cut at the same interval as the repeat of patterns and/or indicia on the strip of material. To initially line up the die and patterns applied on the strip of material, an operator offsets a registration target position, which shifts the die patterns up or down the strip of material, effectively lining up the intervals of the strip of material and the die. However, the strip of material can move or slip out of alignment with the rotary die due to factors like a natural camber of the material, splices which may affect the material, other material properties, discrepancies introduced due to previous operations to the strip of material, etc. If one of the patterns is not positioned precisely at the desired location on the strip of material, a “registration error” occurs. One type of registration error may occur in the machine direction, or in the direction of movement of the strip of material, along an X-axis. A second type of registration error may occur in a direction perpendicular to the X-axis, in a side-to-side direction relative to the strip of material along a Y-axis. A third type of registration error may occur if the strip of material and/or the rotary die cylinders are not angled correctly about a theta axis T, which is perpendicular to both the X-axis and the Y-axis.
Manual methods for determining registration errors for each pattern applied to the strip of material are too time-consuming for mass production operations. Prior art automated methods of measuring and calculating registration errors involve complex and/or numerous equations and compare statements, which can slow the processing time and the processing capability needed to determine the registration errors and correct for them “on the fly” or in a substantially continual manner for each pattern.
Accordingly, there is a need for a method and apparatus for correcting registration errors that overcomes the limitations of the prior art.
Embodiments of the present invention solve the above-mentioned problems by providing a rotary die apparatus and method for correcting registration errors in three axes.
One embodiment of the rotary die apparatus includes a rotary die cylinder, a motor, a sensor, actuators, and a control system. The rotary die cylinder has an outer wall and a number of pattern protrusions extending from the outer wall to cut, emboss, or stamp a pattern onto a strip of material. The motor is coupled to the rotary die cylinder to rotate the rotary die cylinder. The sensor senses pre-defined fiducials on the strip of material and output signals including information about the fiducials. For example, the sensor may be a camera configured to capture and transmit image data regarding the fiducials. The actuators adjust the strip of material and/or the rotary die cylinder along an X-axis, along a Y-axis, and/or about a theta axis, wherein the X-axis extends along a direction of feed of the strip of material, the Y-axis extends transverse of the direction of feed of the strip of material, and the theta axis is an axis of rotation perpendicular to the X-axis and the Y-axis.
The control system receives signals from the sensor and calculates a registration error based on a difference between an actual location or orientation of the fiducials and a desired location or orientation of the fiducials. Then the control system outputs control signals to the actuators to adjust the rotary die cylinder while the rotary die cylinder continues to rotate. For example, the control system may command adjustment of the rotary die cylinder relative to the strip of material or the strip of material relative to the rotary die cylinder in accordance with the registration error along the X-axis, along the Y-axis, and/or about the theta axis. In some embodiments of the invention, the control system commands the actuators to adjust the rotary die cylinder or the strip of material for registration error only when pattern gaps (i.e., spaces between pattern protrusions) of the rotary die cylinder are facing the strip of material between pattern protrusions.
Another embodiment of the invention is a method for correcting registration error of a rotary die apparatus. The method includes the steps of actuating a rotary die and feeding a strip of material through the rotary die. Specifically, a rotary die cylinder with pattern protrusions and an anvil cylinder may be rotated in opposite rotational directions from each other continuously at a predetermined rotational speed. The strip of material may be cut, embossed, or stamped with a pattern when fed through the rotary die between the rotary die cylinder and the anvil cylinder. As the strip of material is fed through the rotary die, the method further includes the step of sensing fiducials on the strip of material and sending information from the sensor regarding the fiducials to the control system. Furthermore, the method may include the step of calculating a registration error based on a difference between an actual location or orientation of the fiducials and a desired location or orientation of the fiducials and then outputting control signals to actuators for adjusting the rotary die relative to the strip of material and/or the strip of material relative to the rotary die. Specifically, the registration error may include error amounts along an X-axis or direction of feed of the strip of material, along a Y-axis transverse to the X-axis, and rotationally about a theta axis that is perpendicular to the X-axis and the Y-axis. Thus, the actuators may adjust the rotary die in one or more of the X-, Y-, and theta-axes directions while the rotary die continues to rotate.
The summary is provided to introduce a selection of concepts in a simplified form that are further described below in the detailed description. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter. Other aspects and advantages of the present invention will be apparent from the following detailed description of the embodiments and the accompanying drawing figures.
Embodiments of the present invention are described in detail below with reference to the attached drawing figures, wherein:
The drawing figures do not limit the present invention to the specific embodiments disclosed and described herein. The drawings are not necessarily to scale, emphasis instead being placed upon clearly illustrating the principles of the invention.
The following detailed description of the invention references the accompanying drawings that illustrate specific embodiments in which the invention can be practiced. The embodiments are intended to describe aspects of the invention in sufficient detail to enable those skilled in the art to practice the invention. Other embodiments can be utilized and changes can be made without departing from the scope of the present invention. The following detailed description is, therefore, not to be taken in a limiting sense. The scope of the present invention is defined only by the appended claims, along with the full scope of equivalents to which such claims are entitled.
In this description, references to “one embodiment”, “an embodiment”, or “embodiments” mean that the feature or features being referred to are included in at least one embodiment of the technology. Separate references to “one embodiment”, “an embodiment”, or “embodiments” in this description do not necessarily refer to the same embodiment and are also not mutually exclusive unless so stated and/or except as will be readily apparent to those skilled in the art from the description. For example, a feature, structure, act, etc. described in one embodiment may also be included in other embodiments, but is not necessarily included. Thus, the present technology can include a variety of combinations and/or integrations of the embodiments described herein.
Turning now to the drawing figures, a rotary die apparatus 10 constructed in accordance with embodiments of the invention is illustrated in
The strip of material 12 may be any elongated piece of material known in the art. In some embodiments of the invention shown in
Although
Embodiments of the rotary die apparatus will now be described in more detail. The frame 28 may be any combination of fixed structural components configured for supporting the rotary die cylinders 14,16. For example, the frame may include at least one base plate 34 and at least two flanges 36 fixed substantially perpendicular to the base plate 34 and parallel to each other. The rotary die cylinders 14,16 may be positioned between and rotatably attached to the flanges 36 and/or on a rod extending between the flanges 36. The rotary die cylinders 14,16 may be held in spaced relation to the base plate 34 and in spaced relation to each other by the flanges 36.
The rotary die 13 may comprise one or more rotating cylinders, such as the rotary die cylinder 14 and anvil cylinder 16 illustrated in
In some embodiments of the invention, the anvil cylinder 16 has an outer wall with a solid outer surface or a number of inward depressions or cavities that inversely match the shape of the pattern protrusions on the rotary die cylinder 14. The rotary die cylinder 14 may be pressed into engagement with the anvil cylinder 16 to form either crush-cutting or shear-cutting nips therebetween. Alternatively, the rotary die cylinders 14,16 may have any rotary die configurations known in the art.
The motor 18 may be one or more rotary motors or any device known in the art for actuating rotation of at least one of the rotary die cylinders 14,16. The motor 18 may comprise any number of gears having pre-fabricated gear ratios and configured to transfer rotational movement of the motor 18 to at least one of the rotary die cylinders 14,16. The motor 18, its gears, and/or the rotary die cylinders 14,16 may be physically coupled with each other such that the motor 18 actuates one of the rotary die cylinders 14 to rotate in a first direction (e.g., counterclockwise) and actuates the other of the rotary die cylinders 16 to rotate in a second direction (e.g., clockwise). In some embodiments of the invention, the motor 18 may rotatably drive one of the rotary die cylinders 14, which may cooperatively actuate the other of the cylinders 16 to rotate in the opposing direction. In other embodiments of the invention, two separate motors may be used for the two separate rotary die cylinders 14,16. The motor 18 may additionally or alternatively include a drive electrically and/or communicably coupled with the control system 30 to control the motor's speed, direction, and/or an amount of power provided to the motor 18.
The sensor 24 may comprise any type of camera, optical sensor, color mark sensor, and/or any other device operable to detect the fiducials 26 printed or otherwise placed on the strip of material 12. As illustrated in
The control system 30 may comprise any number or combination of controllers, circuits, integrated circuits, programmable logic devices such as programmable logic controllers (PLC) or motion programmable logic controllers (MPLC), computers, processors, microcontrollers, or other control devices and residential or external memory for storing data and other information accessed and/or generated by the rotary die apparatus 10. The control system 30 may be coupled with the sensor 24, the motor 18, associated drives, the actuators 32, and/or other switches, sensors, and components through wired or wireless connections, such as a data bus (not shown), to enable information to be exchanged between the various components. The control system 30 may be configured to receive signals from the sensor 24 or related components, calculate a registration error along or about a plurality of axes, and command the actuators 32 and/or the motor 18 to take corrective action based on the calculated registration error for each pattern. The control system 30 may be configured to implement any combination of the algorithms, subroutines, or code described herein to calculate the registration error for each pattern or sensed fiducial.
The control system 30 and computer programs described herein are merely examples of computer equipment and programs that may be used to implement the present invention and may be replaced with or supplemented with other controllers and computer programs without departing from the scope of the present invention. The features of the control system 30 may be implemented in a stand-alone device, which is then interfaced to a rotary die apparatus or system. The control features of the present invention may also be distributed among the components of the rotary die apparatus 10. Thus, while certain features are described as residing in the control system 30, the invention is not so limited, and those features may be implemented elsewhere.
The control system 30 may implement a computer program and/or code segments to perform some of the functions and method described herein. The computer program may comprise an ordered listing of executable instructions for implementing logical functions in the control system 30. The computer program can be embodied in any computer-readable medium for use by or in connection with an instruction execution system, apparatus, or device, and execute the instructions. In the context of this application, a “computer-readable medium” can be any means that can contain, store, communicate, propagate, or transport the program for use by or in connection with the instruction execution system, apparatus, or device. The computer-readable medium can be, for example, but not limited to, an electronic, magnetic, optical, electro-magnetic, infrared, or semi-conductor system, apparatus, or device. More specific, although not inclusive, examples of the computer-readable medium would include the following: an electrical connection having one or more wires, a portable computer diskette, a random access memory (RAM), a read-only memory (ROM), an erasable, programmable, read-only memory (EPROM or Flash memory), an optical fiber, and a portable compact disk read-only memory (CDROM).
The control system 30 may be programmed or otherwise configured to determine a registration error relative to three different axes based on the signals received from the sensor 24. The term “registration error” may refer to an offset distance between where a particular pattern 20,22 should be applied to the strip of material 12 and the actual location where the pattern 20,22 will be or is being applied on the strip of material 12. Additionally or alternatively, the registration error may be a difference between an actual location or orientation of the fiducials 26 and a desired location or orientation of the fiducials. The registration error may be determined based on image analysis of images received from the sensor 24 or camera. Additionally or alternatively, the registration error may be determined based on data signals output by the sensor 24 and/or measurement devices associated therewith, such as rotary encoders or the like. At least one of the actuators 32 may be commanded by the control system 30 to adjust one or both of the rotary die cylinders 14,16 along an X-axis, along a Y-axis, and/or about a theta axis T or θ-axis, based on the sensed registration error. As illustrated in
In some embodiments of the invention, a distance between patterns on the rotary die cylinder 14, referred to herein as a pattern gap 40 as illustrated in
The actuators 32 may be used for adjusting alignment of the rotary die 13 relative to the strip of material 12 according to commands from the control system 30 which are determined by signals received from the sensor 24. The actuators 32 may include a three-crank adjustment mechanism, such as the illustrated on in
As illustrated in
The actuators 32 may additionally or alternatively be replaced by and/or include traditional stand-alone actuators for independent adjustments, such as speed or direction adjustments of the web and/or the rotary die. For example, temporarily increasing or decreasing the rotary speed of the rotary die cylinders 14,16 may be used to correct a registration error along the X-axis, as described in U.S. Pat. No. 8,910,570, incorporated by reference herein in its entirety. In other embodiments of the invention, feed mechanisms may increase or decrease the speed at which the strip of material 12 is fed through the rotary die 13.
The actuators 32 may also include manual or automated actuators for separating the rotary die cylinders 14,16 laterally away from each other, thereby opening the rotary die 13. The control system 30 may command the rotary die cylinders 14,16 be actuated away from each other and remain in this open configuration while the rotary die 13 and/or the strip of material 12 is adjusted by the actuators 32 along the X-axis, along the Y-axis, and/or about the theta axis to correct any registration error. This opening would be required to take place during the pattern gap 40, as described above. However, in other embodiments of the invention, opening or separating of the rotary die cylinders 14,16 in order to make the registration error adjustments described herein may not be required.
A single strip of material may be substantially simultaneously or sequentially fed through multiple rotary die apparatuses, similar or identical to the rotary die apparatuses 10 described herein. For example, one of the rotary die apparatuses may apply a first pattern, and a next one of the rotary die apparatuses may apply a second pattern to the strip of material. In one embodiment of the invention, as illustrated in
Additionally or alternatively, a supplemental rotary die having supplemental pattern protrusions extending outward therefrom may be spaced apart from and aligned along the X-axis with the rotary die 13 described herein. The supplemental rotary die apparatus may have an X-axis, a Y-axis, and a theta axis and may be configured to cut, emboss, or stamp the pattern or a supplemental pattern onto the strip of material. The supplemental rotary die may be moveable along these axes via supplemental actuators. The supplemental actuators may be configured to receive signals from a supplemental control system or the control system 30 to independently adjust the supplemental rotary die relative to the strip of material or to independently adjust the strip of material relative to the supplemental rotary die. For example, the supplemental actuators may adjust the supplemental rotary die at least one of: along the X-axis, along the Y-axis, and about the theta axis of the supplemental rotary die using any of the actuation techniques described herein.
In some embodiments of the invention, the rotary die apparatus 10 may also comprise feeding mechanisms (not shown) such as pairs of rollers presented forward of and/or aftward of the rotary die 13 for cooperatively nipping, tensioning, and/or feeding the strip of material 12 in contact with the rotary die 13. The invention may include these and other conventional components of rotary die apparatuses without departing from the scope of the invention.
Operation of the rotary die apparatus will now be described in more detail. The strip of material 12 with the plurality of spaced apart fiducials 26 is fed between the rotary die cylinders 14,16. When the sensor 24 detects one of the fiducials 26, the control system 30 uses data and/or images received from the sensor to determine the registration error. The rotary die cylinders 14,16 can then be adjusted by a desired amount to correct this calculated registration error along the X-axis, along the Y-axis, and/or about the theta axis T. The timing of such adjustments may be determined based on a number of variables such as the pattern gap 40, rotational speed of the rotary die cylinders 14,16, and other variables programmed into the control system 30, so that the adjustments may be made on-the-fly, while the rotary die 13 continues to operate, but between patterns, so as not to negatively affect a pattern being applied to the strip of material 12.
The flow chart of
The method 2100 may include a step of actuating the rotary die 13, as depicted in block 2102. This may include rotating the rotary die cylinder 14 and/or the anvil rotary die 16 continuously at a predetermined rotational speed via turning on the motor 18. As noted above, the speed of the motor may be controlled by the control system 30 and/or may be a fixed speed without departing from the scope of the invention.
Next, the method 2100 may include a step of feeding a strip of material through the rotary die 13 between the cylinders 14,16, as depicted in block 2104. This may be accomplished via feed rollers, manually feeding, and/or the actuation of the rotary die 13. The strip of material 12 may thus be cut, printed, embossed, or stamped with a pattern when fed through the rotary die 13.
The method 2100 may further include the steps of sensing the fiducials 26, as depicted in block 2106, via the sensor 24, and the control system receiving information from the sensor 24 regarding the fiducials 26, as depicted in block 2108. The fiducials 26 on the strip of material 12 may be sensed, filmed, photographed, or otherwise recorded as the strip of material 12 is fed through the rotary die 13. For example, a camera may be used to record and send images to the control system 30 for comparison to previously-stored images, programmed or stored variables, and/or other programmed or sensed information.
Next, the method 2100 may include a step of the control system 30 calculating a registration error of the fiducials 26, as depicted in block 2110, based on a difference between an actual location or orientation of the fiducials 26 and a desired location or orientation of the fiducials 26. The registration error may include registration error amounts along an X-axis, along a Y-axis, and about a theta axis. Then, the method 2100 may include a step of outputting control signals from the control system 30 to the actuators 32, as depicted in block 2112. Specifically, the control signals may command the actuators 32 to adjust both cylinders 14,16 of the rotary die 13 relative to the strip of material 12 in accordance with the registration error calculated along the X-axis, along the Y-axis, and/or about the theta axis on-the-fly while the rotary die 13 continues to rotate. Additionally or alternatively, the registration error calculated along the X-axis may be corrected by actuation of the strip of material 12 relative to the rotary die 13, while the registration error of the Y-axis and the theta axis may still be controlled via actuation of the rotary die 13 along the Y-axis and/or about the theta axis.
In some embodiments of the invention, the control system 30 may command the actuators 32 to adjust the rotary die 13 for registration error correction only when the pattern gaps 40 of the rotary die cylinder 14 are facing the strip of material 12 between pattern protrusions 42. Likewise, registration error correction along the X-axis via the speed of the rotary die 13 or the speed of the strip of material 12 may only be adjusted for registration error correction during the pattern gaps 40 of the rotary die cylinder 14.
In some alternative embodiments of the invention, the method may include a step of the control system 30 commanding opening of the anvil cylinder 16 and the rotary die cylinder 14 laterally away from each other along the theta axis, as depicted in block 2114, and commanding the rotary die 13 to remain open while registration error adjustments are made by the actuators 32, as depicted in block 2116.
In an alternative embodiment of the invention, as illustrated in
However, the rotary die apparatus 110 may alternatively include actuators 132 having a stacked X-Y-T mechanism with three moveable frames, labeled St, Sy, and Sx respectively in
As illustrated in
Although the invention has been described with reference to the preferred embodiment illustrated in the attached drawing figures, it is noted that equivalents may be employed and substitutions made herein without departing from the scope of the invention as recited in the claims.
Having thus described various embodiments of the invention, what is claimed as new and desired to be protected by Letters Patent includes the following:
