Manufacturing container or tube from paper; or other manufacturi – With printing or photographic reproduction – And cutting – breaking – tearing – or abrading
Reexamination Certificate
2001-08-01
2004-02-17
Rada, Rinaldi I. (Department: 3721)
Manufacturing container or tube from paper; or other manufacturi
With printing or photographic reproduction
And cutting, breaking, tearing, or abrading
C493S340000, C493S363000, C493S365000, C083S171000, C083S676000, C083S698510, C083S934000, C083S698610
Reexamination Certificate
active
06692424
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to an apparatus and method for trimming signatures and, more particularly, to a system for obtaining high quality, precision trim cuts of signatures.
BACKGROUND OF THE INVENTION
Post press signature finishing equipment including such items as folders, rotary trimmers, and various types of stackers, transporters and palletizers are regularly being required to handle greater rates of throughput as printing presses are continually being developed with increasingly fast operating speeds as otherwise high production speeds can be quickly lost post press. For rotary trimmers, this means that the knife needs to be able to maximize the number of cuts, e.g. 15-30 million trims, before requiring maintenance for sharpening or replacement of the cutting surfaces thereof. With high throughputs, trimmers undertake more cuts in a shorter period of time so that if the blade needed maintenance after a relatively few number of cuts there would be unduly frequent downtime for the production line due to the in-line rotary trimmer. This is especially undesirable if the knife starts creating low quality cuts in the middle of a press run requiring interruption of production for knife maintenance.
In rotary trimmers, proper setting of the clearance gap between the rotary knife and anvil is extremely important as that will in large part determine whether the trimmer generates high quality trims over a long knife life. Thus, maximizing knife life is of paramount concern because resharpening the knives is expensive, especially if it goes dull during a press run, as mentioned. Assuming the proper knife/anvil gap is set, they will cooperate with each other to cut or sever edge portions of the signatures with a scissors-like action generating clean, square cut surfaces. However, if this gap is too small or tight, the knife will quickly dull due to the excessive applied force at the cutting edges thereof. As opposed to a scissor-like severing action applied to the signatures, the dulling knife and anvil will exert more of a tearing or ripping action that generates fuzzy cut surfaces. On the other hand, if the gap is too large or loose, then the knife/anvil will not cut at all. Because the difference between a properly set knife and an improperly set knife can be the result of a change in the gap of only thousandths of an inch, setting of the knife/anvil gap needs to be a precise operation.
Currently, rotary knives of trimmers are usually adjusted by very low wage operators whose turnover rate generally is very high. A rough adjustment mechanism is provided to advance the knife toward a lower anvil that is mounted for some vertical overlap with the knife. The operator is supposed to select a feeler gauge with a thickness corresponding to the gap between the blade and anvil needed to generate high quality trim cuts for the particular sheet material to be trimmed. The operator carefully inserts the gauge into the cutting area between the knife and anvil and holds it there with one hand while reaching back with their other free hand to operate the adjustment mechanism for advancing the knife until the gauge is clamped between the knife and anvil. Then, using the adjustment mechanism the operator slightly backs up the knife just enough to allow them to free the gauge.
Of course, at this point the gap is necessarily larger than the gauge thickness so that already it is likely that there will be some quality concerns in cutting with the knife so set. Also, requiring the operator to insert the feeler gauge into the cutting area brings them dangerously close to cutting surfaces on the rotary knives increasing chances for injury. Moreover, as is apparent, this is an arduous procedure that frequently is just not done by low wage operators who instead try to eyeball the adjustment of the knife so that there is the correct gap between it and the anvil.
After this initial set-up, operators are instructed to let the rotary trimmer run for about fifteen minutes, and to then recheck the gap to determine whether the knife/anvil spacing has shifted due to thermal expansion of the knife assembly, and thus if the knife needs to be backed up to maintain the gap at its desired size. However, it has been found that it is very rare for operators to ever undertake this secondary check of the knife/anvil spacing especially since it is inefficient in that it requires the rotary trimming line to be shut down while the rechecking takes place. Since it is the usual case that the knife/anvil gap is not rechecked, it is much more likely that the knife life will be seriously compromised due to thermal expansion.
Directing ambient air into a shroud extending about the knife has been attempted to address the problem of excessive heat at the cutting edges which can cause the ink and varnish at the cut edges to smear and can also cause burning of the cut edges. However, this approach will not be satisfactory in avoiding the reduction in size of the knife/anvil gap during trim cutting operations as heat is also generated at other portions of the knife assembly beyond just at the knife head.
Manufacturers of rotary trimmers and the knives thereof want to be able to market their machines based on how many high quality trims one can expect to obtain before knife maintenance should occur. In this way, their customers can plan for knife maintenance to avoid generating excessive amounts of spoiled product, i.e. signatures with poorly cut surfaces by dull knives. In other words, customers want to be able to plan press runs so they will not be started with a knife that will need to be sharpened or replaced in the middle of the run, which also increases undesirable downtime, as previously discussed.
Certain known variables relating to the paper to be cut such as type, content, weight and thickness, for example, as well as operating speed of the trimmer can be factored in to allow manufactures to determine the knife life a customer can expect. However, the current situation where human operators are required to properly set-up the trimming machine as set forth earlier make such determinations virtually impossible as it has been found that significant inconsistencies in knife life and trim quality arise between different customers that cannot be attributed to differences in the other known variables. Of course, this makes sales of rotary trimmer knifes more difficult as very meaningful statements regarding knife life correlated to the known variables are hard to substantiate. Instead, very large ranges for knife life are specified, e.g. 15-30 million trim cuts, and even so, reaching this range still depends on proper set-up of the machine including the knife/anvil gap spacing.
Accordingly, a need for a rotary trimmer apparatus and signature trimming method exists that provides precision adjustments of the knife/anvil gap to be made in an accurate, easy and efficient manner. Further, a rotary trimmer apparatus and method that allow for high quality trims to be consistently made over long knife lives would be desirable.
SUMMARY OF THE INVENTION
In accordance with the present invention, a rotary trimmer apparatus and signature trimming method are provided that allow the gap spacing between a rotary knife and anvil to be easily and precisely set prior to operation of the apparatus with the knife staying sharp for a maximum number of trims to generate high quality cuts therewith, without the need to recheck the set knife/anvil spacing as previously required. To this end, the present invention allows an operator to incrementally shift the rotary knife to one of the plurality of predetermined spaced positions relative to the anvil without the need for separate special tools or the like. Further, during operation, the knife is maintained at the selected position via a temperature control system for a rotary spindle shaft to which the knife is mounted. The temperature control system maintains the temperature of the rotating shaft substantially constant between its temperature during set-up to its temperature during trim
Harwardt Peter
Langston Macy
Pasman Roman G.
Gammerler Corporation
Rada Rinaldi I.
Truong Thanh
LandOfFree
Rotary trimmer apparatus and method does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Rotary trimmer apparatus and method, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Rotary trimmer apparatus and method will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3349880