Cutting – Processes
Reexamination Certificate
2000-01-28
2001-11-20
Ashley, Boyer (Department: 3724)
Cutting
Processes
C083S145000, C083S620000, C083S685000, C083S686000, C083S690000
Reexamination Certificate
active
06318223
ABSTRACT:
This invention relates generally to a process and apparatus for producing an endless seamed flexible belt, and more particularly concerns forming the ends of the flexible belt in a puzzle cut pattern which interlock to form a very low profile seam.
Initially, flexible belts were fabricated by taking two ends of a web material and fastening them together by a variety of techniques such as sewing, wiring, stapling, providing adhesive joints, etc. While such joined or seamed belts are suitable for many applications, such as the delivery of rotary motion from a source such as a motor, to implement a device such as a saw blade, they are not as satisfactory in many of the more sophisticated applications of belt technology in common practice today. In the technology of the current day, many applications of belts require much more sophisticated qualities and utilities, and in particular, for such special applications as in electrostatographic imaging apparatus and processes using a flexible photoreceptor belt or a flexible electroreceptor belt, in combination with either a intermediate transfer member, or image transport devices, or fusing member, or transfix devices in the flexible belt form. It is ideal to provide a seamless flexible belt whereby there is no seam in the belt which mechanically interferes with any operation that the belt performs or any operation that may be performed on the belt. While this is ideal, the manufacture of seamless belts requires rather sophisticated manufacturing processes which are expensive and are particularly more sophisticated, difficult and much more expensive for the larger belts. As a result, various attempts have been made to provide seamed belts which can be used in these processes. Previous attempts to manufacture seamed belts have largely relied on belts where the two opposite ends of a rectangularly cut sheet of the belt material have been lapped or overlapped and ultrasonically welded to form the seam, or have butted against one another and then fastened mechanically by heat or other means of adhesion such as by the use of an adhesive.
The belts formed according to the typical butting technique while satisfactory for many purposes are limited in bonding, strength and flexibility because of the limited contact area formed by merely butting the two ends of the belt material. Furthermore, belts formed according to the lapping or overlapping and ultrasonic welding technique have excessive seam thickness which provides a bump or other discontinuity in the belt surface leading to a significant height differential over the adjacent portions of the belt, of 0.003 inches or more depending on the belt thickness, which leads to performance failure in many applications. In electrostatographic imaging process utilizing an overlapping ultrasonically welded seamed belt, two most severe problems that the imaging bell: has encountered during the imaging and cleaning processes are, for example, one involves cleaning the imaging belt of residual toner after transfer of the toner image due to the excess in seam height, while the other is the dynamic fatigue seam cracking as a result of large induced bending stress when seam bends and flexes over various belt support rollers of the belt module caused by the increase in seam thickness. Therefore, with a bump, crack or other discontinuity in the seam area of the belt, the cleaning function of a blade is affected which allows toner to pass under the blade and not be effectively cleaned off from the imaging belt surface, since intimate contact between the imaging belt and the cleaning blade is not maintained. A crack in the seam has also been seen to become a site that collects and traps toners which are eventually spewed out to the imaging zones of the imaging belt surface causing copy printout defects. Furthermore, seams having differential heights may, when subjected to repeated striking by cleaning blades, cause the untransferred, residual toner to be trapped in the irregular surface morphology of the seam. As a consequence, an electrostatographic imaging belt which is repeatedly subjected to this striking action, during imaging and cleaning processes, tends to delaminate at the seam when the seam is subjected to constant battering by the cleaning blade. Since the severe mechanical interaction between the cleaning blade and the seam also causes blade wear problem, the result often observed is that both the cleaning life of the blade and the overall life of the imaging belt under a service environment can be greatly diminished as well as degrading the copy print-out quality. In addition, the mechanical striking of the cleaning blade over the excessive seam height has also been found to give rise to vibrational disturbance in imaging development zone which affects the toner image formation on the belt and degrades resolution and transfer of the toner image to a receiving copy sheet. Moreover, the discontinuity or seam bump in such a belt may result in inaccurate image registration during development, inaccurate belt tracking and overall deterioration of motion quality, as a result of the translating vibrations. This is particularly prevalent in those applications requiring the application of multiple color layers; of liquid or dry developer on an imaging belt surface to form the colored toner images, which are subsequently transferred to the final receiving copy sheet. Another disadvantage is that the presence of the discontinuity in belt thickness at the seam area has also been seen to reduce the flex life and continuity of strength of the belt during dynamic fatigue belt cycling when belt bends over various belt support module rollers.
Therefore, for all practical application purposes and prolonging a belt's service life, it is desired to provide a seam height differential between the seam and the unseamed adjacent portions less than 0.001 inch or not to add more than 20 percent of the unseamed parent material thickening.
It has been shown that an endless seamed belt, having very small seam height differential, can be formed with patterned interlocked ends, the pattern of the ends being formed by using a laser or a die to cut the pattern and the patterned cut ends being brought together to interlock to form a seam. In experiments the patterned seams were first generated using a CO
2
laser programmed to make various patterned node sizes and spacings. Although the laser was an excellent tool for providing the cut pattern geometries and conditions, however it was a costly and timely process and an inappropriate process for manufacturing seams for large volumes of belt production implementation because the focused CO
2
laser has a fine beam size that has to make hundreds of bends, twists, and turns in order to produce the small node pattern cuts as the laser traverses across the whole wide of the imaging web. Since the CO
2
laser is a heat laser, the generated heat that melts and cuts the imaging web material has been found to cause heat induced material shrinkage of the cut patterns. Alternatively, a 1 inch length punch press die was designed to cut small belt seam samples for testing purposes. The die cut is much faster and cleaner than the CO
2
laser cut and the die cut was determined to be the preferred method to be used in the patterned seam belt manufacturing process; unfortunately, the mechanical force employed for cutting the imaging web is also seen to cause the material to develop permanent deformation. To yield the desirable seam cut pattern, the size of approximately 0.5 mm and the spacings of approximately 25 microns for the nodes, it requires very accurate cutting by a die. Such a requirement has been found to be impossible for a die to maintain and provide the demanding tolerances for the width of an operational belt seam.
In essence, both the CO
2
laser and mechanical die cutting methodologies have their respective undesirable shortcoming of causing imaging material dimensional change at the vicinity of the cut patterns, which have a precise shape tolerance to yield the perfect seam mat
Hammond William A.
Schlueter Jr. Edward L.
Thornton Constance J.
Yu Robert C. U.
Ashley Boyer
Egan Wayne J.
Xerox Corporation
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