Electric heating – Metal heating – By arc
Reexamination Certificate
1998-04-02
2001-02-20
Heinrich, Samuel M. (Department: 1725)
Electric heating
Metal heating
By arc
C219S121670, C219S121820, C219S121840, C156S272800
Reexamination Certificate
active
06191382
ABSTRACT:
FIELD OF INVENTION
This invention relates generally to a dynamic apparatus for applying energy from a laser to cut or mark successive sheets or zones on sheet stock or web stock material.
BACKGROUND
Dies are widely used to cut variety of patterns on a workpiece, however, there are number of shortcomings with the use of a die. For example, individual dies must be custom made for a specific cut requirement, which can be very expensive. Also, after a period of cutting, dies must be retooled or replaced as they get worn-out. Consequently, during the life of a die, the quality of the cuts made by the die degenerates, thus producing inconsistent qualities of cuts over that period of time. Productivity may also be limited because under some circumstances, before a die can cut into a workpiece, the workpiece must be stopped.
Another consequence of die-cutting is a formation of dust surrounding the die-cutting area. This dust is formed because dies are designed to cut almost through the web, instead of all the way through, thereby leaving the bottom-most area uncut. Consequently, the bottom-most area because of its weakness breaks off, which ultimately separates that sheet from the web. However, when the bottom-most area breaks off, fiber residue is created forming the dust. One of the reasons for not having the die cut all the way through is to prevent the upper die from bearing against the hard surface of the lower mating die. Thus, formation of the dust is inherent with the die-cutting, which is problematic for the press and the operators nearby working on the press. Additionally, the lack of close tolerance of a die makes it difficult to cut partially through the workpiece, i.e. control the depth of the cut on the workpiece.
Another shortcoming with the die-cutting is the scrap or waste, which is produced during the initial start up and shut down. Rotary dies, for example, requires the press to run at a defined speed, in order to cut properly. The speed of the press, however, accelerates during the period of start up and decelerates during the period of shut down. Accordingly, during the periods of startup and shutdown, the quality of the die cuts are inconsistent and much scrap is produced.
Furthermore, since a die can only cut one particular configuration at a time, production process may be limited. For example, sets of index tab sheets are generally manufactured by employing a die-cutting mechanism, which cuts one particular tab location from a pile of sheets. Thereafter, dies are adjusted or changed so that another pile of sheets are cut with the next index tab location. This process is repeated until all of the index tab sheets forming a set have been cut. After all the stacks of individual index tab sheets forming a set have been cut, they have to be collated in the right tab order for packaging, i.e. individual tab sheets must be pulled from each stacks and organized sequentially into a set. This additional step is both time consuming and labor intensive, and at the same time, taking up valuable manufacturing floor space to store the stacks of index tab sheets.
Others have employed laser beams to cut on a moving web to alleviate some of the shortcomings of the die-cutting process. For example, U.S. Pat. No. 5,679,199 to Nedblake et al., describes an upper and lower laser beams, which are shiftable in the Y axis (vertical) in order to cut through a web to form patterns as the web moves past the laser beams.
U.S. Pat. No. 4,549,063 to Ang et al., describes a system that has a plurality of lasers cutting on a moving web. The disclosed system also controls the depth of the cuts by regulating the relative velocity of the beam and the web, the power output of the laser, and the diameter of the focused spot of the laser, or a combination of these.
U.S. Pat. No. 4,049,945 to Ehlscheid et al., describes a method and apparatus for cutting a predetermined pattern on a moving web wherein a laser beam is deflected by a series of pivotable mirrors. These mirrors are controlled so as to cause the laser beam to trace and cut a predetermined pattern. The laser beam moves only in rectilinear motion, as does the web of material to be cut. The direction of motions are not parallel, so that a desired pattern may be cut by controlling the relative speeds of the laser beam and the moving web of material.
The laser cutting systems, as described above, still have a number of shortcomings. For instances, using a laser, as described above, to cut the sets of index tab sheets would still require a separate collating process. Also, using laser beams to cut a moving web creates its own set of problems. These problems include the vapors which are formed when a laser beam is used to cut a moving web, creating mechanical problems for the apparatus and dangerous working condition for the operators. Also the inherent nature of the prior laser cutting system creates extremely sharp edges, which may cause “paper cuts” for the users, as they come into contact with the sharp edges. Furthermore, normal operation of the press in the prior systems creates disturbances on the moving web causing laser to cut inaccurately on the moving web. Additionally, none of the above patents disclose a method in which the controller keeps track of the exact horizontal and vertical location of the moving web so that the laser may be directed to cut on the precise location of the moving web.
For the foregoing reasons, there is a need for a dynamic laser cutting apparatus that may interface with commercial web press, for cutting a variety of configurations on the moving web with precision, without the aforementioned shortcomings.
SUMMARY OF THE INVENTION
Accordingly, a general object of this invention is to provide a dynamic laser cutting apparatus (hereinafter DLCA) for cutting a moving feed stock or successive sheet areas without the aforementioned problems. In particular, one object of the present invention is to provide a laser cutting apparatus that can interface with a commercial web press, to improve the productivity and quality of cutting a moving web. Viewed broadly, the present invention is a dynamic system that has various capabilities, such as (1) directing the laser along the precise location of the moving web to cut successively a plurality of configurations; (2) precisely controlling the power level of the laser to cut consistently depending on the speed of the moving web; (3) precisely controlling the power level of the laser depending on the speed of the moving web to control the depth of cutting; (4) precisely guiding the laser to cut along the desired location of the moving web; (5) pulsating the power level of the laser for a variety of partial cutting operations, such as a micro-perfing and scoring; (6) precisely controlling the focal point of the laser on the edges of the moving web to substantially bevel the edges; (7) providing instrument clean air near the cutting area to keep the cutting area free of vapors; (8) providing ventilation to remove the vapors; (9) cutting successive sheets with index tabs in different locations from a high-speed moving web, thereby eliminating the need for collating the individual index tab sheets, after they are cut by the DLCA; and (10) using multilayer webs to cut labels and the like.
In order to accomplish these and other objectives, DLCA viewed from the broad perspective preferably interfaces with a conventional web press for moving the web through the press at a high speed, with the sheets being printed if desired. The moving web may be periodically marked with registration marks, which indicate the beginning of the next sheet to be cut.
The DLCA preferably includes the following:
A frame configured to interface a dynamic laser cutting apparatus with a moving web.
A control device with a memory for controlling the laser cutting operation.
A laser device mounted on the frame for providing laser beams necessary to cut the moving web.
A scanner coupled to the frame and preferably adjacent to the laser device for directing the laser beam to cut one of the configurations store
Avery Dennison Corporation
Heinrich Samuel M.
Oppenheimer Wolff & Donnelly LLP
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